Correct pistons for rpm heads 360?

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Timeless

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Hi!

I'm trying to find hyperteutic pistons (because of my budget) that fits for rpm alu heads.
I'm looking for cr around 11-11.7
Quench would have to be between 0.04-0.036

KB offers -11,2 dome pistons hyperteutic and forged, but only forged ones fits with the rpm heads. Hyperteutic domes are designed for open chamber heads.

Flat top piston are +5cc, so i would have to mill the heads to 58cc combustion chamber to get 11.6cr and dynamic compression 8.6 with the cam i'm planning to use.

Do you guys know or have any recommendations for suitable pistons for these heads?
 
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With an uncut deck, the comp height of the KB190 piston will be around .012" below the deck. The .050" dome will stick out around .038". So you would need a .075" or so thick head gasket to provide a .037" nominal quench gap with the closed chamber Edelbrocks. SCR would be just over 10:1 at that point. NG

Are you using the 63 closed chamber or the 65 cc 'open' chamber Edelbrocks? If using the 65 cc 'open' ones, then the KB190's should work out fairly close with an .028" thick head gasket. The .038" protrusion of the domes out of the block would end up protruding approx .010" above the head gasket and leave you with a .050" quench distance, and an SCR of around 11.3 SCR. You could mill .010" off the heads to get that down to .040"; SCR would go up to around 11.5 then.

Your quench gap would not be perfect with the KB190's as the lowered edge of the dome would leave a small sliver of much larger quench gap around the periphery; so some of the quench 'squirt action' would go there rather than out into the main chamber. I can't say if or how much that might be detrimental to quench benefits.
 
BTW, if you have the 63 cc heads, and if you have access to someone who will do reasonable cost milling, then you could take the KB190's and mill flat the small dome area above the eyebrows and then mill flat a small bit of the dome on the opposite edge (to accomodate the 63 cc chamber shape opposite the valve side). A rough estimate is that this will remove about 2.5-3 cc's of dome volume. With a .028" head gasket, the quench gap would be around .040", and SCR would be around 11.2. I would be sure to check the dome to chamber clearance all around if you go this route, as well as dome thickness (which I suspect will be OK).
 
Thanks for your quick and very precise answers!
I think the best solution now is to use KB107 flat tops and mill the heads.
 
Roger.... keep in mind that you will need to mill around .010" or perhaps a bit more for each CC chamber decrease with those chambers. But your quench gap will be in good shape with the .028 gasket.
 
The KB-107's, Edelbrock heads and a gasket to suite is an excellent way to go. It's is Often the way I build my performance engines.

You should be able to get to 11-1 this way. Minor head milling maybe done for more Compression.

Click here; Compression Ratio Calculator - Wallace Racing
 
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