P.P.W9's and the goal of more HP
What is that on the valve spring seat area? Is the bare aluminum flaking?
That is what’s left of a spring shim after being pounded on by the valve spring.......for a long time.
That set of heads had quite a few issues, one of which was the springs were installed .110” taller than they should have been, which lowered the spring loads way to low for them to maintain control of the valvetrain.
And when the springs are run hard into the unhappy place over and over, they fatigue....... and then the load drops even more.
The free length of some of the springs had actually gotten quite a bit shorter.
These heads were being run with a decent sized hyd roller cam and 1.6 rockers.
The calculated seat load for a new spring at the as installed height of 1.990 would have been 120lbs.
The observed seat load for the used springs was 100-110.
