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Unfortunately, since I had a brief act of mindlessness the other night and ran over a Belgium block curb and bashed my oil pan pretty good, I am set to pull motor and replace the pan. I have had a annoying drip from the rear main seal since I put this car together and figure "while its out" I might as well install a new seal. 

I been doing research on the interweb and found that "seal crush" is the topic of the month for rear main seal installation on the 385 series motors. 

Any input, suggestions or actual experiences for me on this ? Your help and guidance would be appreciated.

Thanks, Jay

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Follow the procedure detailed in section 21-01 of the Ford Shop Manual.. The biggest thing often overlooked is the pin in the rear main cap seal groove. If it is still in the bottom of the groove it must be removed. It is there to prevent the original rope seal from moving in the groove. Trying to install a modern rubber split lip seal without removing the pin will result in an immediate leak. With the rubber seal you don't have to worry about the seal crush and trimming like on the old rope seals. Just be careful when pushing it into place in the top groove, so you don't shave some of the rubber off on the sharp edges of the groove.


Use a thin coat of sealer between the cap and block aft of the seal. You need something that squeezes out so you don't interfere with the bearing clearance. I use an anaerobic thread sealer, no clearance issues and it doesn't cure until the cap is tightened down. You don't want much, just a thin bead of it, you don't want it to get into the seal.



“If you can't explain it simply, you don't understand it well enough.”

--Albert Einstein


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My understanding is the aftermarket 2 piece rear main seals are not be made to the proper dimensions. In essence, one or both halves of the seal are too long so when installed are not properly sealing. The solution I have read is to file each seal such that the end extends .010-.020 past the end of the block or cap when the other end is flush. Once this crush dimension has been set, you clock the seal have slightly from the parting line and install with a dab of silicone as usual.


Or you can buy the Kaase "one piece" rear main seal.

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73 conv. 460, D0VE large valve heads, Performer RPM manifold, Voodoo 227/233 cam, Holley 950 HP carb, C6 trans, 3.25 trak-loc.

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  • 2 weeks later...

There is a one piece seal available also . From memory Jon Kaase sells it . It takes a single cut so as to slip it over the crank to fit .

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