Grinding, " diesel " noise under valve covers
They must be around .004-.006
I like them on the street at .003-.0035
My KB 107s ended up at .004 and change, after I took it apart and opened her up twice!
And the top gap at their street spec (.0065per inch bore) was way too tight. I opened it up to towing spec (I don't remember that one, maybe .008?) and that ended both the overheating and the locking up at shut-down. That engine got herself a whole new personality.
At .004 the skirts barely rattle and only for a few seconds.
I jumped the minimum operating temp up, and in the Third summer, she finally became the engine that I thought I had built.
You know what tics me is;
the skirt clearance of those KB107s was listed at a factor that at 4.04 bore worked out to about .0015 IIRC. And that is what I had expected them to be when I got the block back.
Instead I got .003. When I returned to the machine shop somewhat irate, the owner explained to me that there was no way he would clearance the KB107s to .0015. I was pretty upset that IMO, he was calling KB liars; but since his shop is the bigshot shop around here and builds engines for most of the Circle-Track cars hereabouts; I bit my lip.
Fast-forward Two years, and a second set of rings plus gaskets, and there I was at .0042ish with file-fits.
Man am I glad I didn't blow up at that shop-owner.