I have been running them for over 25 years on a few different small blocks.. currently on my 410 c. i. motor ( 360 Magnum block , 40 over, 4 inch stroker crank , 9 1/2 to 1 compression , 585 / 595 lift mech. cam) made 545 hp 520 tq on pump gas..... the heads are pretty stock as made no real porting and I have ran the same old ductile iron ( non roller ) rocker set up for all those years with never a problem. I built a 408 with Indy 360-1 heads and personally I like the W2s better