Pontiac V8 engine
Encyclopedia
Pontiac began as a adjunct to the Oakland division of the General Motors line of automobiles in 1926. Pontiac successfully competed against more expensive 4-cylinder models with their inline flathead 6 engines. After outselling Oakland, Pontiac became the sole survivor of the two by 1932. In addition to the inline 6, Pontiac also had an inline 8 by 1933. These two engines were used through 1954, when Pontiac unveiled its V8 in 1955. From 1955 to 1981 the Pontiac
Division of General Motors manufactured its own engines, distinct from Buick
, Cadillac
, Chevrolet
, or Oldsmobile
. Displacement began at 287 cu in and grew as large as 455 cu.in. (7.5 L) by 1970.
Pontiac engines were used in its U.S.-market cars; Canadian-built Pontiac automobiles generally used Chevrolet
engines. From 1955 through 1959, the Pontiac V8 was also used in some GMC
pick-up truck
s.
, which had served well since 1933. When Robert Critchfield took over as general manager in 1952, however, he launched an ambitious plan to move Pontiac into the upscale, mid-range market segment
occupied by Oldsmobile
, and that demanded V8 power. The development of the new engine was fast-tracked, but since its relatively late development let it take advantage of the experience gained in the Oldsmobile V8 engine
and Cadillac V8 engine
, it was remarkably free of teething problems. The main innovation of the Pontiac engine was the stamped rocker-arm system, which had been devised by Pontiac engineer Clayton Leach in 1948. At the request of Ed Cole
, general manager of Chevrolet
, the layout was also used by the Chevrolet V8 released in 1955, an exception to the customary GM policy of allowing a division one year of exclusive use of an internally developed advance.
Federal emissions standards and the drive towards "corporate" engines shared among all GM divisions led to the progressive demise of the Pontiac V8 through the late 1970s. The last "true" Pontiac V8's, a 265 cu in and a 301 cu in, ended production in 1981.
Pontiac also used the Oakland V8 engine in 1932 only.
During 1951–1952, Pontiac had 23 1953 model production prototypes running tests on the GM proving grounds. These 23 cars were equipped with the new 287 V8 engine. Pontiac planned to produce the 1953 models with the V8, but Buick and Oldsmobile feared a sizeable loss in customers, if they had to compete with Pontiac having a new V8 engine. After hearing from Buick and Oldsmobile, GM's board of directors ordered Pontiac to delay the V8 introduction until 1955. Pontiac's V8 development that started in 1946 was a 269-cubic-inch L head design. The 287 cu in overhead design started in 1949. Pontiac engineers tested their 269 V8 in 1949 or 1950 against a downsized Olds rocket V8 overhead engine. The Olds engine was a 303 cu in, Pontiac reduced the size to 270 cu in for testing against the 269 engine. The test results showed Pontiac that a L head engine couldn't compete with the overhead engines.
engine with wedge combustion chamber
s. It used cast iron
cylinder head
s and a cast-iron block
. An innovative design feature was mounting the rocker arm
s on ball pivots on studs set into the cylinder head, rather than using a separate rocker shaft; this allowed more consistent valve action with less weight than a conventional shaft. All (except the 303 Ram Air V engine and 265 and 301) used 6.625 in (168.3 mm) connecting rod
s.
All Pontiac V8s from 1955 to 1959 were reverse cooled, known as the "gusher" cooling system. It was removed from the design for the 1960 model year because designers moved the generator and the power steering pump from atop the front of the engine down to the front of the heads to accommodate a lower hoodline. However, the 1959 389 engines had the generator in front of the heads with reverse flow cooling still in use. This suggests that the cost of the reverse cooling was the reason for the change to "equa-flow" cooling.
Most iterations had an overall length (to the edge of the water pump
pulley) of 28.25 in, an overall width of 27 in, and a height (not including air cleaner) of 31 in (787.4 mm) × 686 mm × 787 mm). Dry weight ranged from 590 to 650 lb (267.6 to 294.8 kg), depending on displacement and year. Most Pontiac engines were painted light blue. The 1958 370" engine and the 1959–60 389 version was named the "Tempest" V-8 and changed in 61 to the "Trophy" V8. Pontiac in the 1950s was one of a few US manufacturers which did not regularly identify its engine names and sizes with air cleaner or valve cover decals.
The 287 was an "oversquare" engine with a bore of 3.75 in (95.3 mm) and a stroke
of 3.25 in (82.6 mm), for a total displacement of 287.2 cubic inch. Compression ratio
was a modest 8.00:1, with valve diameters of 1.781 in (45.2 mm) (intake) and 1.5 in (38.1 mm) (exhaust). It was rated 180 hp @ 4600 rpm and 264 lbft @ 2400 rpm with a two-barrel carburetor
, 200 hp @ 4600 rpm and 278 lbft @ 2800 rpm with the four-barrel carburetor.
(with manual transmission)
(with Hydramatic
)
For 1957 the V8's stroke was increased to in (90.5 mm), for a displacement of 347 cubic inch. For the first time, Pontiac offered Tri-Power, three two-barrel carburetors with a sequential linkage (replacing the previous dual-quad set-up). Power ratings increased accordingly:
(with manual transmission)
(with Hydramatic
)
Several dealer-installed camshaft
s were optional to increase power further to 310 hp.
Standard only for the Pontiac Bonneville
was Pontiac's first-ever fuel injection
system. A mechanical system built by Rochester
, it was similar in principle, but not identical, to the contemporary Chevrolet "fuelie". Pontiac did not release official power ratings for this engine, saying only that it had more than 300 hp. Contemporary road tests suggest that it was actually somewhat inferior to the Tri-Power engines, although it did have better fuel economy. Only 630 Bonnevilles were produced for 1957, all of them fuel-injected.
The fuel-injected engine was now an option, not standard, on the Bonneville, carrying a staggering price tag of $500 (almost 15% of the car's base price). It was rated at 310 hp @ 4800 rpm and 400 lbft @ 3,000 rpm on 10.5:1 compression. Only about 400 were produced before the fuel injection system was quietly dropped.
through 1966. Beginning in 1961 the Pontiac V-8 (389 and 421) is now called the TROPHY V-8, due to its many victories in racing.
and replaced it with a small-bore version of the standard 389 Pontiac V8. It shared the 389's 3.75 in (95.3 mm) stroke, but its bore was originally 3.78 giving it a displacement of 336 C.I.D.It was rated at 250 hp with 8.6:1 compression and 260 hp at 10.25:1 compression. Both used a single two-barrel carburetor. A 4-barrel version was rated at 280 hp. In 1964 when the new "A" body intermediates came out there was a new corporate (GM) engine size limitation to anything less than 330 cu. in. and so the 326 bore size was reduced to 3.72 giving a true 326 cu.in. The 326 subsequently became the optional V8 engine for Tempests, and later the Pontiac Firebird
, through 1967.
A higher-output version was offered, called the 326 HO (High Output). It had a four-barrel carburetor, dual exhaust, and higher compression, and was good for 280 hp for 1963–1965, and 285 hp for 1966 and the final year, 1967.
The '400' V8 was essentially a bored-out (+.060) 389 with 4.1225 inches (104.7 mm) bore and 3.75 inches (95.3 mm) stroke 400.4 cubic inch. It replaced the 389 in 1967 and remained in production through the 1978 model year.The 1979 cars with a 400, had an engine produced in 1978.
The 400 was a popular performance option for many of Pontiac's cars. The 400 produces a good balance of low end torque and higher RPM power when used with a 4-barrel carburetor or other high airflow components.
In 1967, the cylinder head design was improved for all engines. The valve angle was changed for better breathing. 1967 was the last year for closed-chambered heads. The "670" head was a 1967-only casting, and the last PMD head to have a closed chamber. Pontiac went to open-chambered heads in 1967 to improve power, engine breathing and emissions. The valve size increased as well, to 2.11" intake and 1.77" exhaust valves on high-performance heads. Low-performance and 2-barrel applications got 1.96" intake and 1.66" exhaust valves and pressed in rocker arm studs.
. Power output ranged from 135 hp to 170 hp. The heads were a new design featuring siamesed intake ports. The short-deck block and different intake ports also required the design of a new intake manifold. The Pontiac 301 EC (Electronic Controls) version offered in 1981 produced 155 hp and 245 lbft, although it's rumored that the actual HP was closer to 170 hp. The 1980 301 Turbo was rated at 210 hp @ 4400 rpm and 345 lbft @ 2800 rpm. The 1981 301 Turbo gained the electronic controls with an O2 sensor, feedback ECM and E4ME Quadrajet
providing a slight reduction in output to 205 hp and 340 lbft. Although it is much different than the original 1955-vintage Pontiac V-8 powerplant, the 301 has the distinction of being the last true Pontiac V-8 engine, as Pontiac ceased production of these engines effective April 1, 1981.
From 1977 to 1981 there were 4 distinct 301 versions:
301 2-barrel (135 hp), 301 4-barrel (150 hp), 301 4-barrel 'HO' or 'EC' (170 hp), and the 301 Turbo (210 hp).
The 301 Turbo was unique in that it had a beefier block than the 1977–79 versions (which carried on in the non turbo versions in 1980 and 1981), a very mild camshaft with 0.35 in (8.9 mm) lift and 250 degrees gross duration, a 60 psi oil pump to ensure adequate oil to the oil-cooled Garrett TBO-305 Turbocharger, a rolled fillet crankshaft, a fully baffled oil pan, and a specific 800 cfm
Quadrajet carburetor. This had extra-rich "DX" secondary metering rods and a remote vacuum source for the primary metering rod enrichment circuit to allow the Power Enrichment Vacuum Regulator (PEVR) to release the primary metering rods to move to the up position (enrichment) anytime during boosted conditions. This was to ensure there was enough fuel to cool the cast offset dished pistons. Boost was wastegate limited to 9 psi (+/- 1 psi). The 301 Turbo package mandated air conditioning, THM350 non-lockup automatic transmission (THM350C lockup in 1981 Trans Ams), and 3.08 rear axle gearing.
The 301 Turbo was limited to Trans Am and Formula Firebird production only. Some literature has indicated the 301 Turbo may have found its way into the Chevrolet Camaro Z28. It is unclear if any were ever produced.
stock car racing
and drag racing
competition.
The 421 also marked the end of the option for a forged steel crankshaft. The Armasteel cast crankshaft was the standard crankshaft of the entire Pontiac V-8 line until 1967. While "Armasteel" was no more than a fancy name for a hardened cast iron unit, it did refer to the "locking ball" as opposed to the "flaking" type cast iron found in other engines. In 1967, Pontiac out of concerns the public misunderstood the engineering terms, went to a Nodular cast iron name crankshaft, which they used until 1975.
It was replaced by the 455 for the 1970 model year.
, as GM lifted its restrictions on the use of engines larger than 400 cubic inches (401 in some Buicks) (455's in some Olds 442's from 1968) in mid-sized cars. The Pontiac V8 design differs from most other manufacturers' designs in that the external dimensions of each engine, from 326 - 455 cu in displacement, is identical (AMCs 290-401 engines
identical). The displacement is determined internally with changes to the bore and stroke; therefore, there is no "small block" Pontiac engine. The 455 was used through 1977.
The 455, with its "undersquare" dimensions (long stroke relative to bore), emphasized torque over hp, and though advertised as less powerful than some high-performance iterations of the 400, it had a torque rating of 500 ft/lbs., 55 more ft/lbs. of torque than the 1970 performance 400's. The horsepower ratings of this era were often dubious, with engines rated higher or lower in output for advertising, political, or insurance purposes. Per Pontiac's sales brochure, the 1970 455, for example, had similar parts to the higher rated Ram Air 366 HP 400 cu. in., including the same 288/302 camshaft (manual trans. 455) yet was only rated at 360 HP. The 1970 Grand Prix with the same spec. 455 was rated at 370 HP. For 1971 Pontiac introduced another High Output, H.O., version with standard internal parts, a reinforced block with 4-bolt main bearing caps, and improved cylinder head design with 1/8 inch taller intake ports and special round exhaust ports for better breathing, making some 335 hp/224 kW (310 hp in the more accurate SAE net system), but this was an extremely rare engine (it was standard in the Firebird Trans Am
. In 1973, a further refined and even stronger version, the Super Duty (SD) engine was introduced with "only" 310 hp/231 kW (SAE net) using a similar camshaft specifications to the Ram Air IV 400. The 455 SD used round port cylinder heads similar to those used on the 1971 and 1972 455 HO, with specific "LS2" intake and cast iron exhaust header-manifolds. Still, it was the strongest American engine offered that year. Its power was achieved through bending of EPA
emissions-testing procedures, which led engineers to de-tune the engine to 290 hp via a camshaft change to the same profile used in the early RAIII 400 engines for mid 1973 and 1974, after which point it was discontinued.
While an evolution of the RAIV and H.O. engine designs, the 455 SD was a much improved engine. In addition to the more refined cylinder heads, block casting reinforcements in the lifter galley and main bearing oil pan rail area along with the addition of forged connecting rods with larger 7/16 in bolts, the SD was made with a provision for dry sump oiling from the factory. This truly was a racing engine, detuned for use in passenger cars.
In 1969 Pontiac created several versions of their "tunnel port" engine: a special short-deck version of the V8 for Trans Am
racing and a 400 standard deck version. The factory also experimented with 366 and 428 cu in versions. The cylinder head was patterned after the highly successful Ford 427 tunnel port head. So large were the intake ports that the pushrods ran through the center of the ports via pressed-in tubes.
303 - The revised engine had shorter connecting rods, smaller 2.5 in (63.5 mm) journals, special "tunnel port" heads, and a solid-lifter version of the 400's Ram Air IV camshaft. It shared the 4.125 in (104.8 mm) bore of the 400, but with a 2.84 in (72.1 mm) stroke for a displacement of 303 cu in (5 l). The short-deck engine weighed about 40 pounds (18.1 kg) less than the 400, and had an 8000 rpm redline. The 303 program was promising, with race-ready engines producing 475-525 hp (354.4-391.7 kW) and slated for advertised ratings of 355 hp in the Pontiac Firebird
and 375 hp for the Pontiac GTO
. Concerns about emissions, the response of the automobile safety lobby, and the warranty
implications of a high-revving street engine led to its cancellation.
SCCA Trans-Am series General Competition Rules required an engine to be a "Production" item, and required a production of no less than 250 units. The total number of Ram Air V 303 engines produced is not known, estimates range from the SCCA required 250 units, up to 500 units, with rumors of a handful of Ram Air V 303's making their way into the Pontiac Trans-Am production line. These engines are extremely rare and parts not readily available.
In 1969 the 350 HO was upgraded again with the addition of the 400 HO cam, commonly referred to by Pontiac hobbyists as the 068 cam. Also added was the #48 casting number heads with a 68 cc chamber for higher compression, along with larger 2.11" and 1.77" valves. Free-flowing exhaust manifolds from the 400 RamAir were used late in the model year. This was underrated at 330 hp. Many of GM's other divisions' 350's like Chevrolet, Buick and Oldsmobile and even the base SS396 were
handily beaten by this little 350 "High Output" (HO) Pontiac.
This may be today one of the most overlooked high-performance engines of the era, as it was overlooked by the buyers of larger 400 engines available in the day.
No hood scoop moniker denoted the 220 hp 400 HO except the standard "T/A 6.6". The 185 hp 403 Oldsmobile powered cars had "6.6L Litre". Historically the "T/A" prefix on the hoodscoop noted that it was a Pontiac sourced engine, and those ending in Litre were non Pontiac, with the exception of the 1976 50th Anniversary Pontiac Trans AM model and the overhead-cam 6-cylinder, used rarely, but the firebird in 67 bore this badge.
1977 also had a T/A6.6 option that was rated at 200 hp.
The 455 HO's were similar to the yet to come SD455 in 1973/74. The 455 HO was available in the Firebird (base, Formula and Trans Am), and the LeMans, GTO, T37 and GT37 models. The SD455 took the HO 455 to the next level in durability, power and performance.
Last seen in 1976, ending the era of the 455 HO in lackluster fashion, delivering only a paltry 200 hp. It shared nothing with its 1971 brethren except the displacement. Standard in Catalina/ Bonneville Wagons. Option in LeMans, Grand LeMans, Firebird Trans Am, Catalina, Bonneville and Grand Prix.
The 301 HO was the base Trans AM engine in 1980 and 1981.
The modifications over the standard 301 4-barrel were designated the 301 Turbo "301T" block. This included the ESC (Electronic Spark Control) distributor and controller borrowed from the 301 Turbo, which allowed for higher timing without the penalty of engine damaging pinging or preignition. A large 4" ram air duct to the air cleaner, specific carburetor calibration for the 301 HO, and cam similar in grind to the 220 hp 400 from the 1978–1979 model year were also included. Unfortunately, there were no improvements in the casting number "01" small valve high velocity heads, which would have yielded greater improvements in power.
Features:
Thin Wall, Cast Aluminum Block
4.257 Bore x 3.75" stroke (3.0" Mains)
Forged Steel 6.625" rods (Ram Air V style)
12:1 compression
Mechanical Port Fuel Injection
Large Valve Heads:
2.40" Intake Valve
2.00" Exhaust Valve
Small Valve High Rpm
2.19" Intake Valve
2.00" Exhaust Valve
Splayed Main Caps, head bolts tie into main caps. Head bolts do not pull on the cylinder wall causing distortion.
Cam Drive: Fiberglass Belt
Max RPM (High RPM Engine): >8000 rpm
Engine Weight: Estimated 550 lb (249 kg) complete
Dimensions:
Width: 32"
Length: 32"
Height: 24.6"
Power:
estimated 640 hp @ 7500 rpm
. Nicknamed the "INDY 4", created for the 1961 Pontiac Tempest
, it was essentially the right bank of the 389, sharing most of its tooling and many of its parts (more than 120 were identical). The bore and stroke of in (103.2 mm) and in (95.2 mm) were the same, giving a displacement of 195.5 cu in (3.2 l). This degree of commonality enabled it to be produced on the same lines as the V8, allowing substantial cost savings. A drawback was that the 195 weighed much more than a purpose-designed engine: at about 540 pounds (244.9 kg), it was not substantially lighter than the 389.
The 195 produced 110 hp (gross) at 3800 rpm and 190 lbft at 2000 rpm with a single-barrel carburetor, or 155 hp @ 4800 and 215 lbft @ 2800 rpm with the optional four-barrel carburetor. For 1962 a "power pack" option increased rated power to 166 hp.
The Achilles heel
of the 195 was engine shake. An inline four-cylinder
engine produces unbalanced "couple," shaking in the vertical plane, and modern engineers consider the installation of twin counter-rotating balance shaft
s necessary for engines much larger than 122 cui (2.0 L). The V8-based design of the 195 had no such balance shafts, and costs prohibited adding them. The 195 was instead cushioned by flexible rubber engine mounts designed to isolate the engine from the rest of the car, and its forces were further dampened by the Tempest's unusual driveshaft
. However, if the engine was out of tune or if a spark plug
became fouled, the shaking overwhelmed the dampening of the mounts. A special high-strength timing chain was developed especially for the Tempest 4, since a standard chain would stretch and break rather easily from the inherent vibration in this engine design. The timing chain in the 195 was the same as the 389 initially; the upgraded Tempest chain also works on the V8 engines as a high strength upgrade. As an aside, former Pontiac engineer Malcolm McKellar joked in an interview with Collectible Automobile magazine that he and his fellow engineers sometimes called the four-cylinder Tempest "a traveling fatigue machine."
The 195 was dropped after the 1963 model year.
Pontiac
Pontiac was an automobile brand that was established in 1926 as a companion make for General Motors' Oakland. Quickly overtaking its parent in popularity, it supplanted the Oakland brand entirely by 1933 and, for most of its life, became a companion make for Chevrolet. Pontiac was sold in the...
Division of General Motors manufactured its own engines, distinct from Buick
Buick
Buick is a premium brand of General Motors . Buick models are sold in the United States, Canada, Mexico, China, Taiwan, and Israel, with China being its largest market. Buick holds the distinction as the oldest active American make...
, Cadillac
Cadillac
Cadillac is an American luxury vehicle marque owned by General Motors . Cadillac vehicles are sold in over 50 countries and territories, but mostly in North America. Cadillac is currently the second oldest American automobile manufacturer behind fellow GM marque Buick and is among the oldest...
, Chevrolet
Chevrolet
Chevrolet , also known as Chevy , is a brand of vehicle produced by General Motors Company . Founded by Louis Chevrolet and ousted GM founder William C. Durant on November 3, 1911, General Motors acquired Chevrolet in 1918...
, or Oldsmobile
Oldsmobile
Oldsmobile was a brand of American automobile produced for most of its existence by General Motors. It was founded by Ransom E. Olds in 1897. In its 107-year history, it produced 35.2 million cars, including at least 14 million built at its Lansing, Michigan factory...
. Displacement began at 287 cu in and grew as large as 455 cu.in. (7.5 L) by 1970.
Pontiac engines were used in its U.S.-market cars; Canadian-built Pontiac automobiles generally used Chevrolet
Chevrolet
Chevrolet , also known as Chevy , is a brand of vehicle produced by General Motors Company . Founded by Louis Chevrolet and ousted GM founder William C. Durant on November 3, 1911, General Motors acquired Chevrolet in 1918...
engines. From 1955 through 1959, the Pontiac V8 was also used in some GMC
GMC (General Motors division)
GMC is a manufacturer of trucks, vans, military vehicles, and SUVs marketed in North America and the Middle East by General Motors Company. In January 2007, GMC was GM's second-largest-selling North American vehicle division after Chevrolet, ahead of Pontiac....
pick-up truck
Pick-Up Truck
"Pick-Up Truck" is a song written and recorded by Belgian acid house musician Praga Khan. It is the third single from Praga's eighth studio album, Soundscraper....
s.
History
The development of Pontiac's OHV V8 dates back to 1946, when engineers began considering new engine designs for postwar cars. Despite these experiments, the division's conservative management saw no immediate need to replace the Pontiac Straight-8 enginePontiac Straight-8 engine
The straight-8 was an eight-cylinder, in-line automobile engine that was used in production Pontiacs from 1933 to 1954. Introduced in the fall of 1932 for the 1933 models, it was Pontiac's most powerful engine at the time and was the least expensive eight-cylinder engine built by an American...
, which had served well since 1933. When Robert Critchfield took over as general manager in 1952, however, he launched an ambitious plan to move Pontiac into the upscale, mid-range market segment
Market segment
Market segmentation is a concept in economics and marketing. A market segment is a sub-set of a market made up of people or organizations with one or more characteristics that cause them to demand similar product and/or services based on qualities of those products such as price or function...
occupied by Oldsmobile
Oldsmobile
Oldsmobile was a brand of American automobile produced for most of its existence by General Motors. It was founded by Ransom E. Olds in 1897. In its 107-year history, it produced 35.2 million cars, including at least 14 million built at its Lansing, Michigan factory...
, and that demanded V8 power. The development of the new engine was fast-tracked, but since its relatively late development let it take advantage of the experience gained in the Oldsmobile V8 engine
Oldsmobile V8 engine
The Oldsmobile Rocket V8 was the first post-war OHV V8 at General Motors. Production started in 1949, with a new generation introduced in 1964. Like Pontiac, Olds continued building its own V8 engine family for decades, finally adopting the corporate Chevrolet 350 small-block and Cadillac Northstar...
and Cadillac V8 engine
Cadillac V8 engine
Cadillac was the first automobile maker to mass produce a V8 engine. The company has produced eight generations of V8s since 1914, and was the last General Motors division to retain its own V8 design.-L-Head:...
, it was remarkably free of teething problems. The main innovation of the Pontiac engine was the stamped rocker-arm system, which had been devised by Pontiac engineer Clayton Leach in 1948. At the request of Ed Cole
Ed Cole
Edward Nicholas Cole was an American automotive executive for General Motors.- Career :Cole was the son of a dairy farmer. In his youth, he designed, built, and sold homemade radio sets, and as a teenager became a field representative for a tractor manufacturer...
, general manager of Chevrolet
Chevrolet
Chevrolet , also known as Chevy , is a brand of vehicle produced by General Motors Company . Founded by Louis Chevrolet and ousted GM founder William C. Durant on November 3, 1911, General Motors acquired Chevrolet in 1918...
, the layout was also used by the Chevrolet V8 released in 1955, an exception to the customary GM policy of allowing a division one year of exclusive use of an internally developed advance.
Federal emissions standards and the drive towards "corporate" engines shared among all GM divisions led to the progressive demise of the Pontiac V8 through the late 1970s. The last "true" Pontiac V8's, a 265 cu in and a 301 cu in, ended production in 1981.
Pontiac also used the Oakland V8 engine in 1932 only.
During 1951–1952, Pontiac had 23 1953 model production prototypes running tests on the GM proving grounds. These 23 cars were equipped with the new 287 V8 engine. Pontiac planned to produce the 1953 models with the V8, but Buick and Oldsmobile feared a sizeable loss in customers, if they had to compete with Pontiac having a new V8 engine. After hearing from Buick and Oldsmobile, GM's board of directors ordered Pontiac to delay the V8 introduction until 1955. Pontiac's V8 development that started in 1946 was a 269-cubic-inch L head design. The 287 cu in overhead design started in 1949. Pontiac engineers tested their 269 V8 in 1949 or 1950 against a downsized Olds rocket V8 overhead engine. The Olds engine was a 303 cu in, Pontiac reduced the size to 270 cu in for testing against the 269 engine. The test results showed Pontiac that a L head engine couldn't compete with the overhead engines.
Design
The 1955-up Pontiac V8 was an overhead valveOverhead valve
An overhead valve engine, also informally called pushrod engine or I-head engine, is a type of piston engine that places the camshaft within the cylinder block , and uses pushrods or rods to actuate rocker arms above the cylinder...
engine with wedge combustion chamber
Combustion chamber
A combustion chamber is the part of an engine in which fuel is burned.-Internal combustion engine:The hot gases produced by the combustion occupy a far greater volume than the original fuel, thus creating an increase in pressure within the limited volume of the chamber...
s. It used cast iron
Cast iron
Cast iron is derived from pig iron, and while it usually refers to gray iron, it also identifies a large group of ferrous alloys which solidify with a eutectic. The color of a fractured surface can be used to identify an alloy. White cast iron is named after its white surface when fractured, due...
cylinder head
Cylinder head
In an internal combustion engine, the cylinder head sits above the cylinders on top of the cylinder block. It closes in the top of the cylinder, forming the combustion chamber. This joint is sealed by a head gasket...
s and a cast-iron block
Cylinder block
A cylinder block is an integrated structure comprising the cylinder of a reciprocating engine and often some or all of their associated surrounding structures...
. An innovative design feature was mounting the rocker arm
Rocker arm
Generally referred to within the internal combustion engine of automotive, marine, motorcycle and reciprocating aviation engines, the rocker arm is a reciprocating lever that conveys radial movement from the cam lobe into linear movement at the poppet valve to open it...
s on ball pivots on studs set into the cylinder head, rather than using a separate rocker shaft; this allowed more consistent valve action with less weight than a conventional shaft. All (except the 303 Ram Air V engine and 265 and 301) used 6.625 in (168.3 mm) connecting rod
Connecting rod
In a reciprocating piston engine, the connecting rod or conrod connects the piston to the crank or crankshaft. Together with the crank, they form a simple mechanism that converts linear motion into rotating motion....
s.
All Pontiac V8s from 1955 to 1959 were reverse cooled, known as the "gusher" cooling system. It was removed from the design for the 1960 model year because designers moved the generator and the power steering pump from atop the front of the engine down to the front of the heads to accommodate a lower hoodline. However, the 1959 389 engines had the generator in front of the heads with reverse flow cooling still in use. This suggests that the cost of the reverse cooling was the reason for the change to "equa-flow" cooling.
Most iterations had an overall length (to the edge of the water pump
Water Pump
Water Pump is one of the neighbourhoods of Gulberg Town in Karachi, Sindh, Pakistan. It is near main Water Pump that supplies fresh water to the city of Karachi....
pulley) of 28.25 in, an overall width of 27 in, and a height (not including air cleaner) of 31 in (787.4 mm) × 686 mm × 787 mm). Dry weight ranged from 590 to 650 lb (267.6 to 294.8 kg), depending on displacement and year. Most Pontiac engines were painted light blue. The 1958 370" engine and the 1959–60 389 version was named the "Tempest" V-8 and changed in 61 to the "Trophy" V8. Pontiac in the 1950s was one of a few US manufacturers which did not regularly identify its engine names and sizes with air cleaner or valve cover decals.
287
The V8 engine was introduced for the 1955 model year as the "Strato Streak". Not long before the model year introduction, Pontiac management decided that the entire line would be V8-powered. This was based on results of over 1 million test miles, which was unheard of at the time.The 287 was an "oversquare" engine with a bore of 3.75 in (95.3 mm) and a stroke
Stroke
A stroke, previously known medically as a cerebrovascular accident , is the rapidly developing loss of brain function due to disturbance in the blood supply to the brain. This can be due to ischemia caused by blockage , or a hemorrhage...
of 3.25 in (82.6 mm), for a total displacement of 287.2 cubic inch. Compression ratio
Compression ratio
The 'compression ratio' of an internal-combustion engine or external combustion engine is a value that represents the ratio of the volume of its combustion chamber from its largest capacity to its smallest capacity...
was a modest 8.00:1, with valve diameters of 1.781 in (45.2 mm) (intake) and 1.5 in (38.1 mm) (exhaust). It was rated 180 hp @ 4600 rpm and 264 lbft @ 2400 rpm with a two-barrel carburetor
Carburetor
A carburetor , carburettor, or carburetter is a device that blends air and fuel for an internal combustion engine. It is sometimes shortened to carb in North America and the United Kingdom....
, 200 hp @ 4600 rpm and 278 lbft @ 2800 rpm with the four-barrel carburetor.
316
For 1956 the V8 was bored out to in (100.0 mm), increasing displacement to 316.6 cu in (5.2 l). It was offered in the following forms:(with manual transmission)
- two-barrel carburetor, 7.9:1 compression, 192 hp @ 4400 rpm, 297 lbft @ 2800 rpm
- four-barrel carburetor, 8.9:1 compression, 216 hp @ 4800 rpm, 315 lbft @ 2800 rpm
(with Hydramatic
Hydramatic
Hydramatic was an automatic transmission developed by both General Motors' Cadillac and Oldsmobile divisions. Introduced in 1939 for the 1940 model year vehicles, the Hydramatic was the first fully automatic mass-produced transmission developed for passenger automobile use.-History:During the...
)
- two-barrel carburetor, 8.9:1 compression, 205 hp @ 4600 rpm, 294 lbft @ 2600 rpm
- four-barrel carburetor, 8.9:1 compression, 227 hp @ 4800 rpm, 312 lbft @ 3000 rpm
- two four-barrel carburetors, 10.5:1 compression, 285 hp @ 5100 rpm, 330 lbft @ 2600 rpm.
347
(with manual transmission)
- two-barrel carburetor, 8.5:1 compression, 227 hp @ 4600 rpm, 333 lbft @ 2300 rpm
- four-barrel carburetor, 10:1 compression, 244 hp @ 4800 rpm, 350 lbft @ 2600 rpm
(with Hydramatic
Hydramatic
Hydramatic was an automatic transmission developed by both General Motors' Cadillac and Oldsmobile divisions. Introduced in 1939 for the 1940 model year vehicles, the Hydramatic was the first fully automatic mass-produced transmission developed for passenger automobile use.-History:During the...
)
- two-barrel carburetor, 10.0:1 compression, 244 hp @ 4800 rpm, 350 lbft @ 2600 rpm
- four-barrel carburetor, 10.0:1 compression, 270 hp @ 4800 rpm, 359 lbft @ 2900 rpm
- three two-barrel carburetors, 10.00:1 compression, 290 hp @ 5000 rpm, 375 lbft @ 2800 rpm.
Several dealer-installed camshaft
Camshaft
A camshaft is a shaft to which a cam is fastened or of which a cam forms an integral part.-History:An early cam was built into Hellenistic water-driven automata from the 3rd century BC. The camshaft was later described in Iraq by Al-Jazari in 1206. He employed it as part of his automata,...
s were optional to increase power further to 310 hp.
Standard only for the Pontiac Bonneville
Pontiac Bonneville
The Pontiac Bonneville was an automobile built by the Pontiac division of General Motors from 1957 to 2005. It was introduced as a limited production performance convertible during the 1957 model year...
was Pontiac's first-ever fuel injection
Fuel injection
Fuel injection is a system for admitting fuel into an internal combustion engine. It has become the primary fuel delivery system used in automotive petrol engines, having almost completely replaced carburetors in the late 1980s....
system. A mechanical system built by Rochester
Rochester Products Division
Rochester Products Division was a division of General Motors that manufactured carburetors, and related components including emissions control devices and cruise control systems in Rochester, New York...
, it was similar in principle, but not identical, to the contemporary Chevrolet "fuelie". Pontiac did not release official power ratings for this engine, saying only that it had more than 300 hp. Contemporary road tests suggest that it was actually somewhat inferior to the Tri-Power engines, although it did have better fuel economy. Only 630 Bonnevilles were produced for 1957, all of them fuel-injected.
370
For 1958 the V8's bore was increased again to in (103.2 mm), increasing displacement to 369.4 cu in (6.1 l). The engine is now called the TEMPEST V-8 and will be called this until the end of 1960The fuel-injected engine was now an option, not standard, on the Bonneville, carrying a staggering price tag of $500 (almost 15% of the car's base price). It was rated at 310 hp @ 4800 rpm and 400 lbft @ 3,000 rpm on 10.5:1 compression. Only about 400 were produced before the fuel injection system was quietly dropped.
389
For 1959 the V8's stroke was increased to 3.75 in (95.3 mm), raising displacement to 388.9 cubic inch. This was the beginning of factory supplied performance items such as 4 bolt main bearings and windage trays to reduce friction from crankcase oil. The 389 would remain the standard Pontiac V8 engine through 1966, offered in a bewildering variety of outputs ranging from 215 hp. The 389 was the standard engine for the Pontiac GTOPontiac GTO
The Pontiac GTO is an automobile built by Pontiac Division of General Motors in the United States from 1964 to 1974, and by GM subsidiary Holden in Australia from 2004 to 2006. It is considered an innovative, and now classic muscle car of the 1960s and 1970s...
through 1966. Beginning in 1961 the Pontiac V-8 (389 and 421) is now called the TROPHY V-8, due to its many victories in racing.
326
In 1963 Pontiac dropped the Buick division built 215 aluminum V8 it had offered on the Pontiac TempestPontiac Tempest
The Pontiac Tempest was an entry-level compact produced by the Pontiac Motor Division of General Motors, introduced in September 1960 for the 1961 model year....
and replaced it with a small-bore version of the standard 389 Pontiac V8. It shared the 389's 3.75 in (95.3 mm) stroke, but its bore was originally 3.78 giving it a displacement of 336 C.I.D.It was rated at 250 hp with 8.6:1 compression and 260 hp at 10.25:1 compression. Both used a single two-barrel carburetor. A 4-barrel version was rated at 280 hp. In 1964 when the new "A" body intermediates came out there was a new corporate (GM) engine size limitation to anything less than 330 cu. in. and so the 326 bore size was reduced to 3.72 giving a true 326 cu.in. The 326 subsequently became the optional V8 engine for Tempests, and later the Pontiac Firebird
Pontiac Firebird
The Pontiac Firebird was built by the Pontiac division of General Motors between 1967 and 2002. The Firebird was introduced the same year as the automaker's platform-sharing model, the Chevrolet Camaro...
, through 1967.
A higher-output version was offered, called the 326 HO (High Output). It had a four-barrel carburetor, dual exhaust, and higher compression, and was good for 280 hp for 1963–1965, and 285 hp for 1966 and the final year, 1967.
400
For 1967, Pontiac introduced the 400 cubic inch.The '400' V8 was essentially a bored-out (+.060) 389 with 4.1225 inches (104.7 mm) bore and 3.75 inches (95.3 mm) stroke 400.4 cubic inch. It replaced the 389 in 1967 and remained in production through the 1978 model year.The 1979 cars with a 400, had an engine produced in 1978.
The 400 was a popular performance option for many of Pontiac's cars. The 400 produces a good balance of low end torque and higher RPM power when used with a 4-barrel carburetor or other high airflow components.
In 1967, the cylinder head design was improved for all engines. The valve angle was changed for better breathing. 1967 was the last year for closed-chambered heads. The "670" head was a 1967-only casting, and the last PMD head to have a closed chamber. Pontiac went to open-chambered heads in 1967 to improve power, engine breathing and emissions. The valve size increased as well, to 2.11" intake and 1.77" exhaust valves on high-performance heads. Low-performance and 2-barrel applications got 1.96" intake and 1.66" exhaust valves and pressed in rocker arm studs.
350
In 1968 the 326 was replaced by the 350, which used a 3.8750 in bore and in stroke for a total displacement of 354.71 cubic inch although it was still called a 350 (5.7 L). This engine was offered in both 2bbl and 4-barrel variations similar to the previous 326 engine. In 1968 an HO option was available in the Tempest and Firebirds that was rated at 320 hp.. This engine was also offered in 1969 along with a second HO version. The later 350 HO was rated at 330 hp, and was equipped with the 400 CI large valve heads (# 48's) and the 400 HO camshaft. In 1974 it was used in the GTO and was rated at 200 hp303
In 1969, Pontiac unveiled its Trans Am model Firebird, and since racing rules required a sub-305 cid engine, Pontiac unveiled the 303 for racing models only, never available to the public. Bore and stroke were x , for 300.7 cubic inch. It was rated at 475 hp301
The 301.6 cubic inch 301 was offered from 1977 to 1981 and also installed in other GM cars during those years. The 301 had a 4 in (101.6 mm) bore and 3 in (76.2 mm) stroke. Based in part on designs for the "short deck" 303 cubic inch engine designed for the 1970 racing season, it had a shorter deck than the big V8, and used thin-wall castings to reduce weight. The crankshafts were also unique in the fact that they featured only two counter weights instead of the usual five, and also featured lightened connecting rod journals. This resulted in a lightweight design weighing less than the Chevrolet small-block V-8Chevrolet Small-Block engine
The Chevrolet small-block engine is a series of automobile V8 engines built by the Chevrolet Division of General Motors using the same basic small engine block...
. Power output ranged from 135 hp to 170 hp. The heads were a new design featuring siamesed intake ports. The short-deck block and different intake ports also required the design of a new intake manifold. The Pontiac 301 EC (Electronic Controls) version offered in 1981 produced 155 hp and 245 lbft, although it's rumored that the actual HP was closer to 170 hp. The 1980 301 Turbo was rated at 210 hp @ 4400 rpm and 345 lbft @ 2800 rpm. The 1981 301 Turbo gained the electronic controls with an O2 sensor, feedback ECM and E4ME Quadrajet
Quadrajet
In automobile mechanics, the Quadrajet is a four-barrel carburetor made by the Rochester Products Division of GM that was widely used in General Motors motor vehicles until 1990...
providing a slight reduction in output to 205 hp and 340 lbft. Although it is much different than the original 1955-vintage Pontiac V-8 powerplant, the 301 has the distinction of being the last true Pontiac V-8 engine, as Pontiac ceased production of these engines effective April 1, 1981.
From 1977 to 1981 there were 4 distinct 301 versions:
301 2-barrel (135 hp), 301 4-barrel (150 hp), 301 4-barrel 'HO' or 'EC' (170 hp), and the 301 Turbo (210 hp).
The 301 Turbo was unique in that it had a beefier block than the 1977–79 versions (which carried on in the non turbo versions in 1980 and 1981), a very mild camshaft with 0.35 in (8.9 mm) lift and 250 degrees gross duration, a 60 psi oil pump to ensure adequate oil to the oil-cooled Garrett TBO-305 Turbocharger, a rolled fillet crankshaft, a fully baffled oil pan, and a specific 800 cfm
CFM
CFM is an abbreviation for cubic feet per minute which is a measure of flow for liquids and gases, like air or water. CFM may also refer to:*Calea Ferată din Moldova, the Moldovan State Railway...
Quadrajet carburetor. This had extra-rich "DX" secondary metering rods and a remote vacuum source for the primary metering rod enrichment circuit to allow the Power Enrichment Vacuum Regulator (PEVR) to release the primary metering rods to move to the up position (enrichment) anytime during boosted conditions. This was to ensure there was enough fuel to cool the cast offset dished pistons. Boost was wastegate limited to 9 psi (+/- 1 psi). The 301 Turbo package mandated air conditioning, THM350 non-lockup automatic transmission (THM350C lockup in 1981 Trans Ams), and 3.08 rear axle gearing.
The 301 Turbo was limited to Trans Am and Formula Firebird production only. Some literature has indicated the 301 Turbo may have found its way into the Chevrolet Camaro Z28. It is unclear if any were ever produced.
265
Based on the same short-deck as the 301, the 265.1 cubic inch was offered only in 1980 and 1981, and featured a smaller bore of 3.75 in (95.3 mm) coupled with the same 3 in (76.2 mm) stroke of the 301. It produced 135 hp421
Introduced in 1961 as a dealer installed Super Duty option that had dual four barrels, the 421 cu in (6.9 l) was bored to in (104 mm) and stroked to 4 in (101.6 mm) (421.2 cuin), and also featured larger, 3.25 in (82.6 mm) main journals. Unlike previous enlargements of this engine, it did not replace the 389. The 421 SD became factory installed in 1962 and in 1963 a street version became available from the factory with a four-barrel or tri-power carburetion. The Super Duty versions of this engine were extensively used in NASCARNASCAR
The National Association for Stock Car Auto Racing is a family-owned and -operated business venture that sanctions and governs multiple auto racing sports events. It was founded by Bill France Sr. in 1947–48. As of 2009, the CEO for the company is Brian France, grandson of the late Bill France Sr...
stock car racing
Stock car racing
Stock car racing is a form of automobile racing found mainly in the United States, Canada, New Zealand, Great Britain, Brazil and Argentina. Traditionally, races are run on oval tracks measuring approximately in length...
and drag racing
Drag racing
Drag racing is a competition in which specially prepared automobiles or motorcycles compete two at a time to be the first to cross a set finish line, from a standing start, in a straight line, over a measured distance, most commonly a ¼-mile straight track....
competition.
The 421 also marked the end of the option for a forged steel crankshaft. The Armasteel cast crankshaft was the standard crankshaft of the entire Pontiac V-8 line until 1967. While "Armasteel" was no more than a fancy name for a hardened cast iron unit, it did refer to the "locking ball" as opposed to the "flaking" type cast iron found in other engines. In 1967, Pontiac out of concerns the public misunderstood the engineering terms, went to a Nodular cast iron name crankshaft, which they used until 1975.
428
In 1967 the 421 was bored to in (104.8 mm), increasing its displacement to 427.6 cubic inch. The 428 had the same 4.00" stroke as the 421, and was produced from 1967 to 1969. This engine produced 370 hp, or 390 hp in High Output (H.O.) form. The crankshaft in the 428 also had a N cast on them as opposed to the 421's Armasteel. In 1969, Pontiac also used a revised crankshaft out of a Pearlitic malleable iron, although it still used the" N" casting letter. This new material had stronger alloys in the iron. All 428 engines were factory install in large cars only. However, there were a few dealers that would install a 428 in a customers GTO or Firebird for higher power levels.It was replaced by the 455 for the 1970 model year.
455
For 1970 through 1977, the 428 bore was expanded .030" to 4.155 inches (105.5 mm), combined with a (107.16 mm) stroke, yielding a total displacement of 457.6 cu in (7.5 l). Oldsmobile and Buick also had '455' inch engines about the same time. For the 1970 model year variants of the engine became available on all full-size Pontiacs, the Grand Prix and for the first time as the 455 HO in the Pontiac GTOPontiac GTO
The Pontiac GTO is an automobile built by Pontiac Division of General Motors in the United States from 1964 to 1974, and by GM subsidiary Holden in Australia from 2004 to 2006. It is considered an innovative, and now classic muscle car of the 1960s and 1970s...
, as GM lifted its restrictions on the use of engines larger than 400 cubic inches (401 in some Buicks) (455's in some Olds 442's from 1968) in mid-sized cars. The Pontiac V8 design differs from most other manufacturers' designs in that the external dimensions of each engine, from 326 - 455 cu in displacement, is identical (AMCs 290-401 engines
identical). The displacement is determined internally with changes to the bore and stroke; therefore, there is no "small block" Pontiac engine. The 455 was used through 1977.
The 455, with its "undersquare" dimensions (long stroke relative to bore), emphasized torque over hp, and though advertised as less powerful than some high-performance iterations of the 400, it had a torque rating of 500 ft/lbs., 55 more ft/lbs. of torque than the 1970 performance 400's. The horsepower ratings of this era were often dubious, with engines rated higher or lower in output for advertising, political, or insurance purposes. Per Pontiac's sales brochure, the 1970 455, for example, had similar parts to the higher rated Ram Air 366 HP 400 cu. in., including the same 288/302 camshaft (manual trans. 455) yet was only rated at 360 HP. The 1970 Grand Prix with the same spec. 455 was rated at 370 HP. For 1971 Pontiac introduced another High Output, H.O., version with standard internal parts, a reinforced block with 4-bolt main bearing caps, and improved cylinder head design with 1/8 inch taller intake ports and special round exhaust ports for better breathing, making some 335 hp/224 kW (310 hp in the more accurate SAE net system), but this was an extremely rare engine (it was standard in the Firebird Trans Am
Pontiac Firebird
The Pontiac Firebird was built by the Pontiac division of General Motors between 1967 and 2002. The Firebird was introduced the same year as the automaker's platform-sharing model, the Chevrolet Camaro...
. In 1973, a further refined and even stronger version, the Super Duty (SD) engine was introduced with "only" 310 hp/231 kW (SAE net) using a similar camshaft specifications to the Ram Air IV 400. The 455 SD used round port cylinder heads similar to those used on the 1971 and 1972 455 HO, with specific "LS2" intake and cast iron exhaust header-manifolds. Still, it was the strongest American engine offered that year. Its power was achieved through bending of EPA
United States Environmental Protection Agency
The U.S. Environmental Protection Agency is an agency of the federal government of the United States charged with protecting human health and the environment, by writing and enforcing regulations based on laws passed by Congress...
emissions-testing procedures, which led engineers to de-tune the engine to 290 hp via a camshaft change to the same profile used in the early RAIII 400 engines for mid 1973 and 1974, after which point it was discontinued.
While an evolution of the RAIV and H.O. engine designs, the 455 SD was a much improved engine. In addition to the more refined cylinder heads, block casting reinforcements in the lifter galley and main bearing oil pan rail area along with the addition of forged connecting rods with larger 7/16 in bolts, the SD was made with a provision for dry sump oiling from the factory. This truly was a racing engine, detuned for use in passenger cars.
Ram Air
While not officially called the Ram Air I when it was issued, it was indeed the first in a series of Ram Air V8 engines from Pontiac. This engine was installed in the 1967 GTO/Firebird as the top of the line option and at 360 hp (underrated), it was the most advanced 400 in the line. This carried the 301/313 camshaft, as opposed to the "HO" cam which had less duration and overlap. It also had (along with the HO engine) the famous cast iron "headers" which were much better at reducing backpressure than the regular manifolds. The cast "997" heads had taller valve spring heights than the standard D port heads, making these heads unique.Ram Air II
In 1968, Pontiac manufactured the Ram Air II which was a 400 cubic inch motor. In GTO trim the factory rated the car at 366 HP/445 Tq and 'only' 340Hp/430 Tq in the Firebird despite the fact that the engines were identical (save for a small throttle restrictor tab on the Firebird). The Ram Air II was the first engine that incorporated Pontiac's legendary round port head design in a production vehicle, however the intake port was the same as other D-port heads, leaving a head which exhaust port could nearly match the intake at high valve lifts. The Ram Air II also incorporated the first computer-designed camshaft. This camshaft sported a wild 308-/320-degree duration with 0.47 inches (11.9 mm) lift. This same camshaft was also used in Pontiac's 1969–1970 RA IV production cars. The Ram Air II, when outfitted in the (relatively) lightweight 1968 Firebird, has produced some of the fastest 1/4 mile times of the muscle car era. In recent years, under the pure stock drags racing format, Ram Air II Firebirds (running on bias ply tires) have consistently posted ET's in the low to mid 12-second range. No production Pontiac before or since has run times lower. Without question, the RA II was one of Pontiac's most impressive factory offerings.Ram Air III
The Ram Air III was the base engine in the Judge series of the GTO in 1969 and 1970. It also was the base engine in the Firebird Trans Am of 1969 and 1970. It basically was a 67-8 H.O version with a "Ram Air" air cleaner assembly. It utilized the 288/302 duration camshaft (auto trans.) and used the "744" cam (301-313) in the earlier manual trans versions, later downgraded to the "068" version. It was rated at 366 bhp in the GTO version. The Ram Air III had used a similar block to the Ram Air IV in that it was drilled for 4 bolt mains but used a cast crank and cast rods, and 2 bolt mains in 1969. In 1970 the casting number #9799914 Ram air III 4 bolt main block, also used the 4 bolt main caps on Ram Air applications. This engine also had the distinction of using the cast iron "headers" made famous on the original HO engine in 1967.Ram Air IV
The Ram Air IV replaced the Ram Air II in 1969. All 1968–69 #9792506 Ram Air 400 blocks have 4-bolt caps. The Ram Air IV used the RA II's camshaft but lift in the RA IV was increased to .520 thanks to the use of 1.65 rocker arms (vs 1.50). The RA IV, like the RA II that preceded it, used round port cylinder heads. The RA IV also used a lightweight aluminum intake manifold that produced a weight savings of 10-15 lb. From 1969 though 1970, the RA IV was available in both A-Body (GTO/Judge) and F-body (Firebird/Trans Am) form. While 1969–70 A-body RA IV production was low (1517) only 102 RA IV Firebirds and 55 Trans Ams were built in 1969. RA IV Trans Am production 'jumped' to 88 units built in 1970. Today, any high compression round port Pontiac (i.e. RA II or RA IV) is a highly sought after car due to its low production and superior performance on the street and at the strip. After RA IV production ended, Pontiac continued using its round port cylinder head design in 1971. However, by this time compression had dramatically dropped off, marking the beginning of the end of the muscle car era.Ram Air V
(303, 366, 400, 428)In 1969 Pontiac created several versions of their "tunnel port" engine: a special short-deck version of the V8 for Trans Am
Trans Am
Trans Am may refer to:* Trans Am , a U.S. post rock band* Trans Am , 1996 debut album* Trans-Am Series, an automobile racing series* Pontiac Trans Am, an automobile* Tranz Am, a 1983 video game...
racing and a 400 standard deck version. The factory also experimented with 366 and 428 cu in versions. The cylinder head was patterned after the highly successful Ford 427 tunnel port head. So large were the intake ports that the pushrods ran through the center of the ports via pressed-in tubes.
303 - The revised engine had shorter connecting rods, smaller 2.5 in (63.5 mm) journals, special "tunnel port" heads, and a solid-lifter version of the 400's Ram Air IV camshaft. It shared the 4.125 in (104.8 mm) bore of the 400, but with a 2.84 in (72.1 mm) stroke for a displacement of 303 cu in (5 l). The short-deck engine weighed about 40 pounds (18.1 kg) less than the 400, and had an 8000 rpm redline. The 303 program was promising, with race-ready engines producing 475-525 hp (354.4-391.7 kW) and slated for advertised ratings of 355 hp in the Pontiac Firebird
Pontiac Firebird
The Pontiac Firebird was built by the Pontiac division of General Motors between 1967 and 2002. The Firebird was introduced the same year as the automaker's platform-sharing model, the Chevrolet Camaro...
and 375 hp for the Pontiac GTO
Pontiac GTO
The Pontiac GTO is an automobile built by Pontiac Division of General Motors in the United States from 1964 to 1974, and by GM subsidiary Holden in Australia from 2004 to 2006. It is considered an innovative, and now classic muscle car of the 1960s and 1970s...
. Concerns about emissions, the response of the automobile safety lobby, and the warranty
Warranty
In business and legal transactions, a warranty is an assurance by one party to the other party that specific facts or conditions are true or will happen; the other party is permitted to rely on that assurance and seek some type of remedy if it is not true or followed.In real estate transactions, a...
implications of a high-revving street engine led to its cancellation.
SCCA Trans-Am series General Competition Rules required an engine to be a "Production" item, and required a production of no less than 250 units. The total number of Ram Air V 303 engines produced is not known, estimates range from the SCCA required 250 units, up to 500 units, with rumors of a handful of Ram Air V 303's making their way into the Pontiac Trans-Am production line. These engines are extremely rare and parts not readily available.
SD455
Available only in the 1973 and 1974 Formula Firebird and Firebird Trans AM, the SD-455 consisted of a strengthened cylinder block that included 4 bolt main bearings and additional material in various locations for improved strength. Original plans called for a forged crankshaft, although actual production SD455s received nodular iron crankshafts with minor enhancements. Forged rods and forged aluminum pistons were specified, as were unique high flow cylinder heads. A camshaft with 301/313 degrees of advertised duration, 0.407 inch net valve lift, and 76 degrees of valve overlap was specified for actual production engines in lieu of the significantly more aggressive RAM AIR IV style cam that had originally been planned for the engine (initially rated at 310 hp with that cam), but ultimately proved incapable of meeting the tightening emissions standards of the era. The very modest cam, combined with a low compression ratio of 8.4 (advertised) and 7.9:1 actual resulted in 290 SAE NET HP. The initial press cars that were given to the various enthusiast magazines (e.g. HOT ROD and CAR AND DRIVER) were fitted with the RAM AIR IV style cam and functional hood scoops - a fact that has been confirmed by several Pontiac sources. Actual production test cars ran considerably slower and yielded 1/4 miles times in the 14.5 second/98 MPH range in showroom tune - results that are quite consistent for a car with a curb weight of 3,850 pounds and the rated 290 SAE NET HP figure that some sources suggest was "under-rated." Various Pontiac sources have emphatically stated that NO 310 hp versions of the SD455 were installed in regular production cars. 1975 Factory Service Manual lists the SD455, but the SD455 did not meet emissions for the 1975 model year and was canceled.SD4
While not a V8, the SD4 (Super Duty 4-cylinder) was the last in a line of high-performance Pontiac engines. A 2.7L 232 hp SD4 engine powered the 1984 Indy Fiero Pace Car to over 138 mi/h during the race. The SD4 was never available in a production vehicle, however Pontiac's Performance Parts counter had all the SD4 parts available and one could garner a 2.7L 272 hp version and a 3.2L 330 hp version. All 2000 Indy Fiero replicas came with the 2.5L 92 hp Iron Duke engine.350 HO
In 1968, there was also a 350 "HO" which had an increased power with the addition of higher compression #18 heads (#17 and #46 were the most common 2-barrel heads), a four-barrel carburetor and matching intake that was also used on the 400 and 428 engines. There was also the addition of dual exhaust, and in the case of a stick shift car, a slightly more aggressive cam.In 1969 the 350 HO was upgraded again with the addition of the 400 HO cam, commonly referred to by Pontiac hobbyists as the 068 cam. Also added was the #48 casting number heads with a 68 cc chamber for higher compression, along with larger 2.11" and 1.77" valves. Free-flowing exhaust manifolds from the 400 RamAir were used late in the model year. This was underrated at 330 hp. Many of GM's other divisions' 350's like Chevrolet, Buick and Oldsmobile and even the base SS396 were
handily beaten by this little 350 "High Output" (HO) Pontiac.
This may be today one of the most overlooked high-performance engines of the era, as it was overlooked by the buyers of larger 400 engines available in the day.
400 T/A 6.6
In 1977 the 400 cubic inch T/A 6.6, (RPO code W72) was created to fulfill the vacuum of the lackluster 76 455 HO, with improved flow cyl "6X" casting heads borrowed from the 350 yielding higher compression, specific camshaft, 3.23 gearing, and a new dual muffler exhaust making 220 hp, providing the Trans AM and Formula Firebird with a breath of new life after some dismal performance years. The 4-speed manual transmission was also available behind the 400 HO and the 301 HO. The 400 T/A 6.6 did not live long however, emission standards and fuel economy restrictions for 1980 model year doomed the powerplant. The 301 Turbo replaced the 400 HO in 1980, disappointing potential customers who were just getting excited about performance returning to Pontiac. The 400 HO Trans AM was the last of the performance cars available with the manual transmission, also yet another disappointment to potential customers.No hood scoop moniker denoted the 220 hp 400 HO except the standard "T/A 6.6". The 185 hp 403 Oldsmobile powered cars had "6.6L Litre". Historically the "T/A" prefix on the hoodscoop noted that it was a Pontiac sourced engine, and those ending in Litre were non Pontiac, with the exception of the 1976 50th Anniversary Pontiac Trans AM model and the overhead-cam 6-cylinder, used rarely, but the firebird in 67 bore this badge.
1977 also had a T/A6.6 option that was rated at 200 hp.
400 HO
This engine was first offered in 1967 as the third engine in the GTO and Firebird line (after the 400 2-barrel and the base 400)....It produced 360 bhp, and had the cast iron headers. The camshaft was the HO cam with 288/301 duration. It was the top of the line engine until the 400 Ram Air was introduced later in the year. This engine was offered as an option in 1967 thru 1970.421 HO
First offered as an option in 1963, the 421 HO came in a 4-barrel (320 hp) and with two tri power engines of 353 and 370 hp. Pontiac offered this to the public as a streetable version of the 421 SD. The engine came with 543797 (4-barrel) and 9770716 heads for both tripowers and special exhaust manifolds and a 7H cam with 292deg. intake duration and later 1964 L with 288deg intake essentially the same as the 068 cam.455 HO
The 455 HO designation made its debut in 1970 as appeared on vehicle invoice, rated at 500 ft/lbs of torque and 360 or 370 horsepower depending on the body style. 455 HO's were seen in the 1971 model year with HD blocks, The Round port Heads came as #197 for 1971 year and #7F6 for 1972 year. Both having Round Port Exhaust. Special large valve heads with screw in rocker arm studs, Special aluminum intake with removable exhaust crossover, Special streamlined Ram Air Exhaust manifolds, Higher lift and larger duration camshaft and 800 CFM Quadrajet carburetor with specific jetting.The 455 HO's were similar to the yet to come SD455 in 1973/74. The 455 HO was available in the Firebird (base, Formula and Trans Am), and the LeMans, GTO, T37 and GT37 models. The SD455 took the HO 455 to the next level in durability, power and performance.
Last seen in 1976, ending the era of the 455 HO in lackluster fashion, delivering only a paltry 200 hp. It shared nothing with its 1971 brethren except the displacement. Standard in Catalina/ Bonneville Wagons. Option in LeMans, Grand LeMans, Firebird Trans Am, Catalina, Bonneville and Grand Prix.
301 HO
While not "high output" fashion by the 1960s and 1970s standards and no "HO" moniker on the shaker hood scoop, the 301 did end up with a HO "performance" version, yielding 170 hp with only 4.9L (302 CID) for the 1979–1981 model years.The 301 HO was the base Trans AM engine in 1980 and 1981.
The modifications over the standard 301 4-barrel were designated the 301 Turbo "301T" block. This included the ESC (Electronic Spark Control) distributor and controller borrowed from the 301 Turbo, which allowed for higher timing without the penalty of engine damaging pinging or preignition. A large 4" ram air duct to the air cleaner, specific carburetor calibration for the 301 HO, and cam similar in grind to the 220 hp 400 from the 1978–1979 model year were also included. Unfortunately, there were no improvements in the casting number "01" small valve high velocity heads, which would have yielded greater improvements in power.
427 Hemi TOHC
This was a project started by Pontiac with the end goal of building a Pontiac 427 Hemi. Pontiac asked Mopar (Chrysler, Dodge, Plymouth) for help in designing it and making it work. Surprisingly, Mopar actually agreed and sent over several of the engineers that designed both the 392 and 426 Hemi. The goal of making a Pontiac Hemi succeeded but was never produced.Features:
Thin Wall, Cast Aluminum Block
4.257 Bore x 3.75" stroke (3.0" Mains)
Forged Steel 6.625" rods (Ram Air V style)
12:1 compression
Mechanical Port Fuel Injection
Large Valve Heads:
2.40" Intake Valve
2.00" Exhaust Valve
Small Valve High Rpm
2.19" Intake Valve
2.00" Exhaust Valve
Splayed Main Caps, head bolts tie into main caps. Head bolts do not pull on the cylinder wall causing distortion.
Cam Drive: Fiberglass Belt
Max RPM (High RPM Engine): >8000 rpm
Engine Weight: Estimated 550 lb (249 kg) complete
Dimensions:
Width: 32"
Length: 32"
Height: 24.6"
Power:
estimated 640 hp @ 7500 rpm
195
Perhaps the most unusual variation of the durable Pontiac V8 was not a V8 at all, but an inline fourStraight-4
The inline-four engine or straight-four engine is an internal combustion engine with all four cylinders mounted in a straight line, or plane along the crankcase. The single bank of cylinders may be oriented in either a vertical or an inclined plane with all the pistons driving a common crankshaft....
. Nicknamed the "INDY 4", created for the 1961 Pontiac Tempest
Pontiac Tempest
The Pontiac Tempest was an entry-level compact produced by the Pontiac Motor Division of General Motors, introduced in September 1960 for the 1961 model year....
, it was essentially the right bank of the 389, sharing most of its tooling and many of its parts (more than 120 were identical). The bore and stroke of in (103.2 mm) and in (95.2 mm) were the same, giving a displacement of 195.5 cu in (3.2 l). This degree of commonality enabled it to be produced on the same lines as the V8, allowing substantial cost savings. A drawback was that the 195 weighed much more than a purpose-designed engine: at about 540 pounds (244.9 kg), it was not substantially lighter than the 389.
The 195 produced 110 hp (gross) at 3800 rpm and 190 lbft at 2000 rpm with a single-barrel carburetor, or 155 hp @ 4800 and 215 lbft @ 2800 rpm with the optional four-barrel carburetor. For 1962 a "power pack" option increased rated power to 166 hp.
The Achilles heel
Achilles Heel
Achilles Heel may refer to:* Achilles' heel, a metaphor for a fatal weakness in spite of overall strength* Achilles Heel , music by Pedro the Lion* Achilles Heel , off Antarctica...
of the 195 was engine shake. An inline four-cylinder
Straight-4
The inline-four engine or straight-four engine is an internal combustion engine with all four cylinders mounted in a straight line, or plane along the crankcase. The single bank of cylinders may be oriented in either a vertical or an inclined plane with all the pistons driving a common crankshaft....
engine produces unbalanced "couple," shaking in the vertical plane, and modern engineers consider the installation of twin counter-rotating balance shaft
Balance shaft
In piston engine engineering, a balance shaft is an eccentric weighted shaft which offsets vibrations in engine designs that are not inherently balanced...
s necessary for engines much larger than 122 cui (2.0 L). The V8-based design of the 195 had no such balance shafts, and costs prohibited adding them. The 195 was instead cushioned by flexible rubber engine mounts designed to isolate the engine from the rest of the car, and its forces were further dampened by the Tempest's unusual driveshaft
Driveshaft
A drive shaft, driveshaft, driving shaft, propeller shaft, or Cardan shaft is a mechanical component for transmitting torque and rotation, usually used to connect other components of a drive train that cannot be connected directly because of distance or the need to allow for relative movement...
. However, if the engine was out of tune or if a spark plug
Spark plug
A spark plug is an electrical device that fits into the cylinder head of some internal combustion engines and ignites compressed fuels such as aerosol, gasoline, ethanol, and liquefied petroleum gas by means of an electric spark.Spark plugs have an insulated central electrode which is connected by...
became fouled, the shaking overwhelmed the dampening of the mounts. A special high-strength timing chain was developed especially for the Tempest 4, since a standard chain would stretch and break rather easily from the inherent vibration in this engine design. The timing chain in the 195 was the same as the 389 initially; the upgraded Tempest chain also works on the V8 engines as a high strength upgrade. As an aside, former Pontiac engineer Malcolm McKellar joked in an interview with Collectible Automobile magazine that he and his fellow engineers sometimes called the four-cylinder Tempest "a traveling fatigue machine."
The 195 was dropped after the 1963 model year.
See also
- Pontiac Straight-6 enginePontiac Straight-6 engineLike most American automobile manufacturers, Pontiac relied on the straight-6 design for their circa-World War II automobiles.-186:In the 1920s Oakland Motor Car engineers designed an all new engine for their "companion" make, the Pontiac, which was introduced in 1926. It was a side-valve design...
- Pontiac Straight-8 enginePontiac Straight-8 engineThe straight-8 was an eight-cylinder, in-line automobile engine that was used in production Pontiacs from 1933 to 1954. Introduced in the fall of 1932 for the 1933 models, it was Pontiac's most powerful engine at the time and was the least expensive eight-cylinder engine built by an American...
- List of GM engines