Rear Main Seal Install

Mike69cuda said

Just got off the phone with Felpro tech support. They told me that the 360 rear main seal was designed to be used as supplied with no trimming. This is part# BS 40651.

I have been researching this a lot and have found no evidence of anyone trimming this particular seal. It is designed with the metal ring slightly below the surface of the seal half ends to allow for the Viton to compress slightly when put together. I could not figure out a way to duplicate this after trimming, so I kept searching for more info. According to felpro, the seal is designed to protrude .060 inches or more prior to assembly.

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Call that moron back and ask him how you fit the seal when the block has been line honed. Then ask the moron how many engines he has personally assembled that has been lined honed and didn’t fit the gasket. See what he says.

I can tell you I’ve fixed so many of them it’s really insane that stooge doesn’t know better.

That’s why the one piece seal is a bit better. It’s not nearly as sensitive to line honing as the 2 piece seal is.

It doesn’t matter to me if you fit it or not. But this I’m sure of. If your seal is more than .010 proud of the block or cap, when you torque it down it will go out of round.

If you run into the issue of the seal being too proud, put it the cap and block and torque it on and look with your eyes and see if it’s round. The more crush the seal has the more out of round it will go.

If you do that and it’s not out of round, chances are it will seal.