340 advice

[lazerboat]

I have a 72 340 it was rebuilt before i purchesed it so i pulled the heads and checked cylinders 4.64  60 over  i think 
they seem out of round about .04 thousand of inch,  is that norm ?    The  pistons have 4 valve releafs in them are they stock ?    And sit in the hole about .110 thous. Can I just change out the pistons for higher compression ones and if i do will i have to balence the assy.       Im looking for a good cheap build  i have a set of 302 heads stock  and also  ported j heads what would be better  ,  is a block  that is 60 over  any good   thanks for any help   

[Chryco Psycho]

Stock bore is 4.04 so .060 over would measure 4.1"
if the bores are out of round by .040 the block is junk , if they are out by .004 you will still not get the bores round without boring out to .070 over & yo u would need a custom piston if the block checks out at that bore for adequate wall thickness
 the 302 heads are a small port head designed for the 318 but I know a ported 308 head will out flow the X&J heads so I am not sure if the 302 would as well

[72rtchallenger]

Stock bore is 4.04 so .060 over would measure 4.1"
if the bores are out of round by .040 the block is junk , if they are out by .004 you will still not get the bores round without boring out to .070 over & yo u would need a custom piston if the block checks out at that bore for adequate wall thickness
 the 302 heads are a small port head designed for the 318 but I know a ported 308 head will out flow the X&J heads so I am not sure if the 302 would as well

[lazerboat]

sorry i think  i ment the cylinders are 4.064  is 20 over  is that correct  it seams they are out  of round buy about .004 across the board , the engine seems pretty fresh i can still see the honing marks fantly. are the pistons norm to be .110 in the hole for 72  and do  you think i  could  change to kb pistons  re hone and ring thanks for you help 

[Chryco Psycho]

you need to make the cylinders round to get them to seal
so I would fit the pistons to .030 oversize

[moparnut]

you mean they dont sell out of round pistons?
could have sworn cheby does