john sachs
Well-Known Member
There seems to be some confusion on the meaning of quench and squish. I'll try to explain, in simple terms, the meaning.
Quench and squish are the same thing: the distance of the piston from the deck of the head, including the head gasket, or the radius piston dome(hemi style) from the radius of the combustion chamber(hemi style).
There are ONLY several ways to correct problems in this area.
1- Custom pistons with a taller crown.
2- Machine down cylinders that are too tall.
3- Spin drop the heads.
4- Thinner or no base gaskets. (small corrections).
You can mill the heads to death, and that will NOT tighten up the quench.
The EPA 117" S&S engines have a .040" taller cylinder. Changing head gaskets, milling the shit out of the heads, or using a .010" base gasket, or no base gasket will never deliever the proper quench on one of these engines.
Ideal quench/squish is between .030" and .040"........... meaning -0- deck, and between a .030" and .040" head gasket.
Deck height is the distance of the piston crown to the top of the cylinder. Ideal is piston even with top of cylinder.
The EPA 124" S&S engines have approx. .090" taller cylinders. The ONLY way to fix this nightmare is to cut the cylinders down.
Singh grooves are supposed to help curb detonation, and help tuning.... I've grooved several sets of heads and found nothing different (on the dyno or on the road).
Hope this helps.
John
Quench and squish are the same thing: the distance of the piston from the deck of the head, including the head gasket, or the radius piston dome(hemi style) from the radius of the combustion chamber(hemi style).
There are ONLY several ways to correct problems in this area.
1- Custom pistons with a taller crown.
2- Machine down cylinders that are too tall.
3- Spin drop the heads.
4- Thinner or no base gaskets. (small corrections).
You can mill the heads to death, and that will NOT tighten up the quench.
The EPA 117" S&S engines have a .040" taller cylinder. Changing head gaskets, milling the shit out of the heads, or using a .010" base gasket, or no base gasket will never deliever the proper quench on one of these engines.
Ideal quench/squish is between .030" and .040"........... meaning -0- deck, and between a .030" and .040" head gasket.
Deck height is the distance of the piston crown to the top of the cylinder. Ideal is piston even with top of cylinder.
The EPA 124" S&S engines have approx. .090" taller cylinders. The ONLY way to fix this nightmare is to cut the cylinders down.
Singh grooves are supposed to help curb detonation, and help tuning.... I've grooved several sets of heads and found nothing different (on the dyno or on the road).
Hope this helps.
John
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