With forged pistons you have to have a certain amount of clearance, right? Well someone told me that it's best to get the block bored to match the pistons. We already had the block bored, so what are my options? How do you check clearance? Im thinking about getting the Speed Pro forged pistons. So what should I do about pistons?
Thanks

 

IN THOERY, a 30-over piston should drop right into a true 30-over bore (4.030" exactly) with the proper amount of clearance already. A piston for a 30-over hole will actually be several thousandths shy of 30-over itself and that's where the clearance comes from. Again, IN THEORY. In the real world it's best to measure every piston and have the individual bores honed to give the perfect amount of clearance for the piston that will go in them.

 

all pistons need clearance, some just need more, like forged. (IIRC).

If you overbore it .030" then the hyper pistons might be 4.027", and forged might be 4.025" for example.

But yea, just about any machine shop won't even do the overbore without pistons in hand, since they will want to finish hone the cylinders to each piston. So you give them your block and pistons, and they give you it back with each piston numbered to each bore. If you're going to try to drop 'em in, just use a feeler gauge around the skirt area to check your piston clearance.