guys were asking about after market pistons hitting the heads. on a 401 bored 21 thousand over with longer rods with a off set grind crank giving 3.69 stroke instead of 3.64 stock. pistons were 6 thousand in the hole. with auto tech pistons like Tom sells never hit, that's with 44 thousand head gaskets. now with the red victor 35 thousand head gaskets and milling the head 25 thousands they now hit. there hitting on the outside dome edges opposite of the valve notches on the taller side of the dome. the pistons already were ground down on the corners from auto tech but need more now with the head milling and thinner gasket. on another note the heads were 126 cc's with tulip intake valves, changing to flat valves changed the cc's to 123 cc's, so 3 cc's for tulip valves. now milling the heads 25 thousand took it down to 118 cc's. so cutting the heads 5 thousand takes 1 cc's off the chamber. hope this might be of help
hey Joe! Do we know if the pistons were hitting on the lower contour edges like mine were, or the upper dome edge across the top?
Joe - on mine, it was the side ridge circled below. there may be more areas, the engine is coming back apart ause I still have the noise
