340 Static Compression Numbers and Test Procedure

yellow rose said

Very true, the exact center of an asymmetrical lobe may not be at max lift.

That's why I don't run the lobe to max lift and zero the dial indicator. I zero the dial indicator on the base circle and then subtract .050 or .100 from max lobe lift (for example, if I have a .380 lobe, I'll use .350 or even .280 as a checking point on the lobe) and raise the lifter to that point (example....380 lobe minus .050 is .350) and read the degree wheel. Then I go over max lift and when I get to .350 on the closing side of the lobe, I read the degree wheel again.

The middle of those two readings is the actual ICL.

Click to expand...

That's kind of hard to follow but I can also kind of see the advantages to that method... you should do a video on that!

I agree also on the operating temp aspect, higher compression makes more heat which makes detonation more likely so to compensate you want to run a colder thermostat to keep the chamber temps down and reduce hot spots (and pre-heating of the intake charge during the compression stroke). I had the opposite issue with my current 360, 9:1 static comp with aluminum heads not-very-small cam at 5000' above sea level and cranking compression is only around 110-120 psi. Originally built it with a high-flow 180* t-stat and it never ran much over 170-180, felt like it just wasn't running as efficiently as it could. I recently put in a high-flow 195* t-stat and it runs much better overall; more responsive, more part-throttle power (and feels like more WOT power as well, oddly). Especially after I took out about 4 degrees of overall advance now the engine is very, very happy (and hey my heater works better too! lol).