DaveV, Isky was correct. We alter valve gaps for different tracks which shifts torque range. It's a good testing way to see if another cam would be better suited. I will advise that you only adjust valves when oil is thoroughly hot. Get out there and drive it. Don't think running it in the driveway for a while is adequate. The oil must be hot. Chev measures oil feed temp at rockers. The valves are adjusted while it's running. It can be done with feelers if rocker and valve tip faces are not worn. Or a dial indicator type tool called a Gapper is used.Clearance varies with load or work asked of the engine. A truck working hard needs prox .010 Int, .018 exh . These valve stems expand which closes gap and the valves will close later stealing a bit of power. In essence, lowering Dynamic compression, not the Static compression most people know or talk about. Never set the valves too close. You'll have low manifold vacuum and erratic idling. Myself, I wouldn't run the Int at .007. I've found it's too close. .008-.010 is better, even if you hear them. David
