<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">I measured the two heads I have in use.<div>the 12:1 compression head measures 3.18" and the 11.5:1 head measures about 3.23. Both heads are installed so perfect measurements are tough to get. nonetheless, if your head was milled that much you would have numerous openings into the water passages.</div><div>Two solutions - find another head or two and test them before any work is done to see if you can find a better casting, or consider pop-up pistons.</div><div>I just checked piston to valve clearance on my new engine with modeling clay and there is certainly room to do this, though it may create other problems. I'm running a cam with 0.554" of valve lift and there was easily 0.080" of clearance at the closest condition based on the modeling clay.</div><div><br></div><div><br></div><div><div><div>On Apr 10, 2015, at 9:07 PM, damys--- via Fot wrote:</div><br class="Apple-interchange-newline"><div align="LEFT"><font face="Verdana" size="2" color="#000000" letterspacing="0" kerning="0">So we just got the head back from the sonic test, picture attached. Our numbers are quite a bit less than Chuck's. Do you guys think we will be OK at .065? Our compression, according to our calculations, is 9.76:1. This seems low to us. Our combustion chambers are 34.5 cc's. The total thickness of our head is 3.283, and we're bored .010 over.</font></div><font face="Verdana" size="2" color="#000000" letterspacing="0" kerning="0"><br></font><div align="LEFT"><font face="Verdana" size="2" color="#000000" letterspacing="0" kerning="0">Does the compression seem right for this thin of a head? Are we OK with only .065" of material to the water jacket?</font></div><font face="Verdana" size="2" color="#000000" letterspacing="0" kerning="0"><br></font><div align="LEFT"><font face="Verdana" size="2" color="#000000" letterspacing="0" kerning="0">Thanks,</font></div><font face="Verdana" size="2" color="#000000" letterspacing="0" kerning="0"><br></font><div align="LEFT"><font face="Verdana" size="2" color="#000000" letterspacing="0" kerning="0">Dave and Alex</font></div><span><IMAG1545.jpg></span>_______________________________________________<br><a href="mailto:fot@autox.team.net">fot@autox.team.net</a><br><br>http://www.fot-racing.com<br><br>Donate: http://www.team.net/donate.html<br>Archive: http://www.team.net/archive<br>Forums: http://www.team.net/forums<br>Unsubscribe/Manage: http://autox.team.net/mailman/options/fot/sjanzen@me.com<br><br><br></div><br></div></body></html>