Okay, so i picked up a used 2.5 block from a guy locally. He included the pistons that came with the new block that he ordered.

The block I received calls for 3 "A" pistons and 1 "B" piston. But the pistons I have been given are all As.

I assume that i have to have the bore changed on the 1 b cylinder to match the A piston. Am I correct? Also, will i need to have the crankshaft rebalanced? or will it be okay as it is? Bringing it to the machine shop in the morning so making sure i have everything right the first time around.

Thanks :)

yes, B is the smaller of the bores. So boring the B cylinder out to an A spec would be the right move.

I would have the whole assembly balanced. I frequently see rods from Subaru that are way out. I've had a lot more than 7 grams and a few as much as 10 grams off in weight from the rest.

Lastly, depending on your power levels, go to the large side if not bigger than the stock spec on the ring gaps. I'm actually just about to do a write up on this topic in this forum. I recommend at least .014" top ring and .022" bottom ring.

here's the thread
http://forums.nasioc.com/forums/showthread.php?t=1465986

-Dominic

Thanks alot :-D I greatly appreciate your help. Now another question. Will the machine shop generally do the balancing? or the that somewhere else?

They should. My machine shop does it all. Most do.

I assumed so, to late to give them a call and ask, but thanks a lot for your quick replies. You've been a great help.:D

you're welcome.

-Dominic