O, ok. I’m not familiar with SBCs later than the 70s but my buddy bought a new long block from somewhere and it was supposed to come with the damper installed and the flexplate. When it arrived it had neither. They refunded him some money and told him what to buy. He thought it was strange and asked me. I had no clue. Thanks for educating me!
The engines they built starting in 1986 had a one piece rear main seal. This required that the crank flange be round, so they could not put a counterweight on the flange, so the weight moved to the flywheel/flexplate. They use a smaller bolt pattern for the crankshaft to flywheel bolts. So...all the 86-up small blocks use a neutral damper, but a weighted flywheel. 400 is the only small block with a two piece rear seal, that used a weighted damper and flywheel.
My buddy got good information from the supplier but neither of us had ever messed with the one piece seal engines. So when he asked me, it sounded kinda wonky and since they had screwed up not putting the damper on in the first place it made us kinda question their advice. So, early bolt pattern with a weight - would be a 400 flexplate? Do the SBC and BBC flexplates have the same size weight?
No, he didn’t give me any numbers or anything, just that it was a one piece rear main seal. It’s not a stroker 383 or anything, just a 350. I’ve got a couple flexplates with weights lying around that fit the early crankshaft bolt pattern, now I’m wondering if they are BBC or 400 SBC.
look at the weight, the 454 is bigger., also, not all BBC use the weight, only the 454 does. The 366/396/402/427 are neutral.
@bchctybob Just to fill in the gaps for future reference, can you post the part numbers the builder supplied to your friend? 350 one piece main weighted flexplate and neutral balancer, right? Tooth count? Might help the next guy!
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