312 Rear Main Seal


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By slumlord444 - 13 Years Ago
Teflon rope or rubber seal? Mummerts gasket set comes with the teflon rope seal and he offeres a rubber seal as a seperate option.  Opinions??
By Ted - 13 Years Ago

If the seal surface on the crankshaft is not near perfect, then a neoprene seal will not last very long.  In these cases, a rope or Teflon seal would be recommended. I'll add that if putting a neoprene rear main seal in a 312, make sure it's for a 312 and not a 292.  You're dealing with two different seal sizes in this case.

 

Here’s a link to a past thread showing a picture of a pitted seal surface.

http://www.y-blocksforever.com/forums/Topic61335-3-3.aspx 

By PF Arcand - 13 Years Ago
Ted: Was there not an issue with the rubber seal not fitting properly in some cases, due to 312 block casting variences?
By Ted - 13 Years Ago
When neoprene seals are installed in 312 blocks, it’s prudent to insure that the grooves are not so deep that the seal either barely contacts the crankshaft or doesn’t contact the seal surface of the crank at all.  Just one more nuance to check for on the 312’s.
By slumlord444 - 13 Years Ago
So if the crankshaft seal surface is fine and the seal fits the crank, and yes it is a 312, what would be the prefered seal or does it realy make any difference?