Thread: Help Me Pick Some Heads For Christmas Present

Tweet

Originally Posted by techinspector1

1. I don't understand. What happened to the nice new heads you had ?
2. 0.032" + 0.039" makes a squish/quench of 0.071". Too wide. Use the 0.015" shim gasket with the 0.032" piston deck height for a squish/quench of 0.047".
.

The new heads are still in play. The notes and measurements above are from the current engine setup. I'm just confirming what this 'stock' engine has so I can make sure that 1) I know exactly what I'm working with and 2) can accurately calculate which head gasket thickness I'll need in order to achieve as close to possible SCR of 9.5:1 and quench of 0.040-0.045".

Using the engine's current measurements of 4.00x3.48", 76cc stock chambers, 7cc valve relief volume (approximated), 0.039" gasket thickness, and 0.032" deck clearance I calculate a SCR of 8.34 and 0.071" quench which I agree is ugly.

Now if change to the new heads and plug in the new variables of 67cc chambers & 0.015" gasket, I get a SCR of 9.57 but my quench is 0.047" which is more squish/quench distance than I want right???

Bottom line is I'd like to make sure that I'm ordering the correct head gaskets that keep me within the 9.5:1 & 0.040-0.045" quench range that you all have advised me on.