i LOOKING TO BORE OUT MY 305TPI OUT OF MY 91 Z28,LOOKING AT KEITH BLACK PISTONS,WHICH ARE BETTER THE 4 RELEIFS OR THE 2?AND DOES ANYONE KNOW WHAT THE COMP. RATIO WOULD BE?

 

before you start typing make sure the cap lock is off. thre is no "better" between 2 and 4 valve reliefs. there would be a slight compression increase with 2 over 4 all else being equal. down side to the 2 notch pisotn is there will be a right and left piston but that isn't really much of an issue. without heads the compression is zero with heads it'll be more and until you know what heads there is no way to tell. figure out what heads, how far in the hole the pistons set and the gasket thickness and do the math.