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Help needed with SD's Roush engine

6K views 9 replies 7 participants last post by  HotRodLincoln 
#1 · (Edited)
I finally have the car stripped down for paint. I don't plan on a complete rebuild of this engine, but am planning on new heads.

Basic specs: 4.39 bore, 4.15 stroke, Roush crank, carrillo rods, BRC pistons, 4 bolt block, D3VE heads w/2.25's, adjustable valvetrain, cleaned up ports, solid roller.

Pistons appear to be 18cc dish? There is an old part number on them: BRC 58

As you can see the decks (and old heads) are O ringed. This, along with the larger chamber D3VE heads/dished pistons were part of going to twin turbos which were on the car when I got it. They were done in 1981 by Jack Roush.

With the process of going back to NA, I'm planning on new Blue Thunder aluminum heads, ported/flowed. I would rather not have to groove them for O rings if at all possible.

My question: Can I remove the existing O rings and run a larger diameter bore head gasket safely? I was thinking a 4.67" bore gasket would put the sealing ring outside the existing O ring groove. OR, could I install a smaller diameter O ring material which would not interfere with the head gasket once compressed?

Just looking for options that would be acceptable to avoid grooving the new heads if possible without requiring an entire engine teardown/decking the block. The engine runs perfectly with no issues, so I hate to disassemble the bottom end unless I have to.

Here is a photo of the existing O ring/piston:



Thanks for your expertise! I want to get this right.

Tom
 
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#4 ·
I have a set of C8's that have been machined down to a 52CC chamber and were run on a 16+:1 CR motor that we o-ringed. I'm using them on a much milder combo now and my machinist said pull the o-ring and run them. I did and I am and there's no problem with them leaking @ 11.2:1 with a factory type gasket.
Rob
 
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