Deck Clearance

[oh34v6]

Is there a difference in the piston-deck clearance between fwd and rwd 3.4l blocks? I'm trying to use a CR calculator to determine what size dish I need in my pistons, but this is throwing me off because i've found values of -.02" and .0095". And while I'm at it, i just want to verify that the fwd heads have a combustion chamber of 28.5cc?

[bszopi]

As far as the heads, it depends on which FWD heads you are wanting to use.

As far as the pistons go, it depends on which engine, as pistons have changed over the years, therefore how much the piston comes out of the block (or stays in the block) has also changed.

[oh34v6]

I have a set of 2000+ heads right now. Not sure what the casting numbers are off the top of my head though. I'm using rwd pistons. I'm I correct in thinking that the deck clearance for those is .0095in under the deck? If so, that would mean i would only have to have 2cc removed from the piston dish to get the CR I want.

I just got my hands on a copy of desktop dyno, and man it has me wanting to get this project moving. Definitely gonna go with a custom grind cam now.

[bszopi]

The 2000+ heads should be 28.5cc stock, but any bowl work done with porting can tweak those numbers slightly. As far as the numbers listed in the CR calc for deck height clearance, positive numbers are in the block and negative are out of the block. So yes, you are on the right track.

[oh34v6]

Alright thanks. It does sound like I should double check my chamber volumes after i get done porting just to make sure I'm still looking at the same numbers. I finally have the block torn all the way down, and to my excitement the cylinder walls look like they are freshly honed! In a motor that was supposed to have 80k on it, barely any wear on the pistons either.