I was searching on some older threads and found that you can put stock 243's on an LQ4 and gain a whole point in compression over the 317's. My question is, can you mill the 243's and gain even more compression using the stock LQ4 dished pistons? If so, approx. what would the compression ratio be? Would there be any benefit to this over the 317's, and also will I need different length pushrods?

Any info is appreciated. Thanks!

 

depends on how much you mill. yes a 64.5cc head compared to a 72cc head would net you close to a full point of CR

 

I'm new to all of this so bare with me, but what would be a "safe" amount to mill the heads to without running into clearance problems?

 

well on a LQ4 you would be at 10.5 with 243s, if you would put on a set of 5.3s heads that would take the CR up around 10.9
i think those heads are 61cc

so .015 would get you down to that CC roughtly you can go .030 and take yourself down to 59cc roughly

but for pushrod lenght and etc you would have to check that when assembling motor