[Barry_R]

The Keith Black pistons from many years ago are going to be cast hypers. They require the large end gaps in order to survive. The combination of cast pistons and big gaps is a poor one - and you'd be way ahead with proper fporged pistons and normal rings. The other stuff is better suited to cheap rebuilds on SBCs intended for pickup trucks...

I've handled and inspected more pistons than just about anybody, and the KB stuff is really crude in comparison to Diamond, Probe, JE, CP or any other modern parts. They are on a par with the made in India stuff my former employer (F-M) is pushing these days.

Are the oiling passages feeding the lifters blocked off? That was an old school mod that mirrored what Ford did in the original 427s for solid lifters. I've run that package for a lot of street miles - but you need ot stay on top of spring pressure and keep the idle speeds up. Agains - newer stuff will be better. In any case a solid roller and KB slugs are an intuitive mismatch - budget street pistons and a race cam...