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Old 08-13-2007, 04:47 PM
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In 1986 chevy changed the 2 piece rear main seal to a 1 piece rear seal, The 2 piece was notoriously famous for oil leaks. When they made it into a 1 piece the rear flange was made completely round and a smaller bolt pattern was used, so the flywheel/flexplate from a older 2 piece block will not fit on a 1 piece and vice versa. The rod lenth remained unchanged, as did the bore and stroke lenths of the same cubic inch engines. Whoever recommended using a older 2 piece block hasn`t got a clue about small blocks. They also started using roller cams in passenger car engines in 1986, a roller cam is far superior to any flat tappet cam design. They also changed the heads in those years to a center bolt valve cover with higher paremeters, the valve covers on the older blocks were also famous leakers.
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