so im thinking of stuffing 425 pistons in the 350 short block im going to pick up soon but as always i plan ahead i was thinking of going standard bore forged but gaining some extra cubes would be nice . now i know it can be done but as far as clearances go whats involved as far as pistons skirts go i know the compression heigth is the same for the 425 piston as the 350 but will the skirt hit the counter weight ? any help advice will be appreciated i dont have any parts yet just planning another small block build to play around with

 

They should fit, but it will probably be easier to find .060" over 350 pistons.

 

425 pistons are expensive and hard to find. If you have not bought parts yet, you will be way ahead of the game using 400 SBC pistons and rods. 4.125" bore, get 1.425 p/h and a 6.2" rod, cut the journal .025. You will end up right at zero deck with new, reasonably priced parts.

 

thank you for the info ill look into the chevy piston rod combo but i have my sources for good used olds parts and i know i can snag a set of slightly used 425 pistons reasonably priced i did the same for the current combo i got., i used a nice set of cast flat tops i got for 100 bucks i dont mind using used parts as long as they are good

 

So, for less that $300 you get a set of NEW pistons,
http://www.summitracing.com/parts/SLP-H615CP/
$300 for NEW connecting rods
http://www.summitracing.com/parts/SCA-26200716/

Or, you buy the 45 year old pistons (and hope they are OK), recondition the 40 year old rods, pay to get the pistons pressed on, factor in the $100 saved by not decking, yeah, look at all the money you saved.................

 

X2 plus the OEM pistons and rods are heavy as hell. You're looking at a bobweight difference of over 300 grams per, not worth it in my book.

 

I ran the 40 plus year old pistons in my current 350 and they have held up great 15 runs on the motor and I drove it all summer no issues but we shall see what the budget allows

 

do you guys think it can be done for under 2k all said and done my top end is all fresh as the motor i have now is fairly new but i like to tinker with stuff all the time., so i will re use alot of stuff from my current engine. this is strictly a bottom end im building. The heads were done last year so thats one less expense i have to deal with