455 Buick Rear Main Seal

I found this to be an interesting post from David Powell on the http://www.v8buick.com/ website. I have had exactly the same issue with Ford seal on three of my engines and will soon be going back to the Cadillac version.

Dave Writes:

Remove and inspect the neoprene seal. If the fit isn't correct, they burn up immediately. Once burned, they wouldn't leak too bad at idle, but go out and mash the gas and oil would be coming out of the torque converter inspection cover drain hole when I got back. All it took was for the oil to be forced up against the back of the crankcase during acceleration.I kept burning up those Ford seals that are supposedly a drop in, no matter how well I polished the crank, and no matter what I did to prelube the seal. The Ford seal just hasn't fit well at all in the last two big blocks I assembled. So I went back to the file fit Cadillac 472-500 seal like I always used to use, and have no leaking whatsoever, not even a film of oil. This is on three engines that I have in use currently. And I'm doing a short block with one right now. Won't even waste time trying the Ford seal anymore. For me, the Ford seal was riding the crank with way too much pressure and they came out with the seal lip burnt to a crisp.The Cadillac seal comes a tiny bit big, which allows you to fit it to your block's exact dimensions. That groove was made for a rope seal, so I don't believe that accuracy was a big concern. I leave .010" protrude on all four corners. This loads it hard into the block so that it will not spin, yet leaves just the right amount of pressure on the crank. There is no drop in rear main seal for the Buick 400-455 in my opinion.

David Powell76 LeSabre 2dr 455 13.17@10276 LeSabre 4dr ht 455 14.50@9376 LeSabre 4dr ht 350 -for sale67 Riviera 430 13.96@97 -for sale83 Regal 455 incomplete85 WH1 T-Regal70 Skylark 350 daily ride96 9C1 Caprice69 Camaro 327 4spd78 Monza 32778 K5 Blazer 38377 GM 3/4 Ton 45489 Cutlass (new salt car)etc