spring pressure

[Ian Hill]

Ahh, you have gone too far too! My "valve through the exhaust" sounded like a death rattle at 1100 feet. Ended by splitting the piston in two, one half embedded in the block, half way up the bore, the other half scattered throughout the other 7 holes!

It was actually caused by coil bind, but I'd imagine similar results if it did happen.

I have been increasing valve pressure buy .01" shims and am up to .06" intake and .03" exhaust over recommended and each time I add shims the car picks up. The next race I go to I will be matching the ex with the intake. It is a largerjump than I've done so far, but I am guessing it will be good as I did the intake first and have been catching up with exhaust with good results. I've discussed this lots with my engine builder and we decided to go with the idea that more is better, to the point we wipe the cam shaft out. This will be season two coming up, the last cam had three seasons without fail. As far as telling you what my spring pressure is, I don't think it matters. My combo likes the springs stiff. Just like valve lash, my combo runs near to zero as I dare go... I set them cold and I set them tight. But that's for another thread I am sure.

What I will tell you is at what spring pressure I wipe the cam out...if it happens. I switched Joe Gibbs oil this past seaon, this is the first time I am not freshening my engine, everything, including the cam looks good. I figure I'll get to coil bind before hurting the cam.
Ian