rear main seal

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Old Mar 1, 2025 | 05:20 AM
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RowureOlds442's Avatar
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rear main seal

I am rebuilding my E block 400 and using the ford bb rear main seal . My question is should i use a little silicone in the main cap and block under the seal ? Seams to fit snug without any . Thanks
Old Mar 1, 2025 | 06:08 AM
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No silicon.
Old Mar 1, 2025 | 06:20 AM
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Offset the seal about 5 degrees relative to the split line and use a small dab of silicone at the ends of the seal. That's all.
Old Mar 1, 2025 | 10:55 AM
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Thanks for the answers there will be more questions coming .
Old Mar 1, 2025 | 12:45 PM
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Be very careful with the RTV. I have seen 2 cases over the years where too much of it actually caused a leak. This is from the Fel Pro instructions:

"Put a tiny dab (1/8" or smaller) of RTV on each end of the lower seal, where the seal ends meet, taking care to avoid the sealing lip. Less is better in this case."

https://www.felpro.com/technical/tec...main-seal.html
Old Mar 1, 2025 | 12:52 PM
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I'm not sure but I think you need to machine the crank. The stock crank can chew up the replacement seal.. I'm not 100% sure about what is needed. I just remember ready something like this.
Old Mar 1, 2025 | 12:56 PM
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Originally Posted by OldOldsLover
I'm not sure but I think you need to machine the crank. The stock crank can chew up the replacement seal.. I'm not 100% sure about what is needed. I just remember ready something like this.
That is not really true. I have probably done 20 rope to rubber conversions over the years and have never done it and have not had an issue. If the engine is apart you could run the crankshaft polisher over it but to be honest with you after 40 years of the rope seal running on it there really will not be any sharp edges anyway.
Old Mar 1, 2025 | 01:07 PM
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Originally Posted by BillK
That is not really true. I have probably done 20 rope to rubber conversions over the years and have never done it and have not had an issue. If the engine is apart you could run the crankshaft polisher over it but to be honest with you after 40 years of the rope seal running on it there really will not be any sharp edges anyway.
Thsts good info. Thanks, as i said i wasnt sure. No 1st hand experience. Cheers
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