The piston suppliers told me they needed the cc's of my heads to choose the right piston for the 10.25:1 compression I want. My heads are stock, #3904390. A book I found lists the cc's at 96.4 and a response to my earlier posting regarding this was 98.4. When I talked to summit racing (on-line supplier) I told them I was interested in their cast, hypereutectic pistons. They told me that both these cc's figures are incorrect and too low. Anyone have a specific piston recommendation(part# would be great) that will provide the compression ratio I am looking for.
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Re: '66 BB 390HP COMPRESSION RATIO/PISTON CHOICE
Rob-----
The guys at Summit are the ones that are incorrect. The combustion chamber volume for the GM #3904390 cylinder heads is 98 cc, nominal. Depending on how many valve jobs that yours have had, the volume might be a little greater by now.
There are many factors that will affect final compression ratio. However, a set of Keith Black/Silvolite #KB 176 will give you a final compression ratio right at what you're shooting for. These pistons will be MUCH stronger than the original pistons used for L-36 engines, too.
If you use these pistons, make sure that you follow the KB recommendation for top ring end gap.In Appreciation of John Hinckley -
Re: '66 BB 390HP COMPRESSION RATIO/PISTON CHOICE
Rob, I read in an earlier thread where you're looking for some info on hypereutectic pistons. Here's the URL for KB Pistons and if you go to the Tech Info tab, then Articles, you'll find good technical info.
RogerComment
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Re: Made A Mistake, Sorry
It wasn't Rob looking for that info, it is a gentleman named Peter Martin. Sorry.
RogerComment
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Re: '66 BB 390HP COMPRESSION RATIO/PISTON CHOICE
the 96.4 CCs are the specs that GM posts in the AMA specsComment
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Re: '66 BB 390HP COMPRESSION RATIO/PISTON CHOICE
Thanks for the specific information, I appreciate it...Comment
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