06-21-2017, 03:05 PM
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#27
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VIP Member
Join Date: Apr 2002
Location: Coarsegold, CA
Posts: 1,016
Likes: 57
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Re: cometic head gaskets
Quote:
Originally Posted by BillK
Rick,
Are they ARP studs ? Did you use ARP lube or just oil ? If they are ARP studs the torque spec is 80 lb ft with ARP lube. If you used oil it would be higher.
I personally think that the finish would really have to be bad to make them leak. If you could see some of the factory cylinder head finishes that I see you would understand why I say that. They are pretty terrible yet they don't leak. I always put the proper finish on them when I machine them but I don't know if it is your problem.
Now if the deck or the heads have low spots in them I could see it.
Years ago one of the Fel Pro performance engineers told me to do the following when torqueing race engine heads.
1. Torque the heads as usual to the correct torque.
2. Let them sit overnight
3. Start with the first bolt in the pattern, loosen it 1/2 turn and then torque it back to specs in one step. Continue through the pattern one bolt at a time doing the same thing.
This method works much better than just putting your toque wrench on and re-torqueing the fastener because typically the breakaway torque to get the bolt or nut moving again is a lot more than the final torque spec.
If you try this, mark one of the bolts or nuts before you loosen it. Then re-torque it and see how much more it turns. I typically see close to 1/8 turn.
I do this on almost every engine I do and have basically not had any head gasket issues.
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That's a good one...
I'm going to file that away with my old guy tricks....
I hope that you don't mind me stealing it....
That how I will re-torque in the future, even though I don't have sealing problems....
I don't think that would work with head bolts that have the bolt holes that extend into the water jacket???
Would breaking the bond of sealer between the bolt threads and the tapped hole cause a coolant leak???
My Pontiacs have blind holes and now that studded blocks are legal it isn't a problem for my race engines. So I am gathering info for other projects....
Thanks again for the info...
Bob
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Bob Mulry 7516 STK
A & M Motorsports
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