On my 3.4 (newly installed in an MGBGT) the distributor leaks. The leak is around the 0'ring. I am using a distributor from a 1985 2.8 since i converted the 3.4 to carburetion. I changed the o'ring just to make sure and it did nothing to help. Any ideas? Is this common and is there a cure? PS the distributor is a rebuilt delco-remy HEI distributor. Thanks in advance.