K-nite
Registered User
You could try head saver shims from SBI or Felpro. They are about .010" metal shim cut like head gasket. I have never used them, though. It's an option. The shim goes under the gasket.
IDI piston height
- Thread starter Mikey89014
- Start date
tanman_2006
Full Access Member
Look up cosmetic gaskets for thicker.
Mikey89014
Full Access Member
I think i'm most likely going to get the rods shortened, or the 3 taller pistons shaved .008 and balanced as a set, whatever is cheaper.
racer30
Full Access Member
I cut .030 off my pistons. The pistons lost 22 grams of weight, then I carefully removed about 8 grams more from the pistons until they all were within .3 grams. If you havent had your rotating assembly balanced yet I think milling is your best bet. the machine work on the rods will cost way more than cutting the pistons and you get lower CR and a lighter piston to boot.
Mikey89014
Full Access Member
Thanks a lot,
How much do you think cutting 3 pistons and balancing 8 will cost?
How much do you think cutting 3 pistons and balancing 8 will cost?
icanfixall
Official GMM hand model
I think $200.00 will get the pistons milled and balanced total. Call around and ask balance questions. Anything that turns around the crank will need to be part of the balance shot. Main bearings are no part of the shot. They don't move but everything else moves around the crank.
Your 7.3 block is 40 over on the cylinders and the decks are 20 under? That's a little scarey. Are you sure you don't want to find a block that's never been machined and start with it? There is little room for error when it comes to piston to head/valve clearence on these IDI's, plus, 40 over on the bore puts cavitation (of one or more cylinders) into the coversation as well. Not trying to confuse the situation further, but another block is an option you should consider at least.
Just my two cents.
Heath
Just my two cents.
Heath
icanfixall
Official GMM hand model
I personally feel 20 over is about the max a person should attempt to overbore these problematic 7.3 blocks but... A 40 over may not have an issue either. Its a really tuff call because nothing is cast in stone about this. We know some block for the 7.3 cavitated as early as 50,000 or so miles and some that were not taken care of ran fine for well past 300,000 miles. So there is no reason to believe this will or will not work.. Its a chance to take.
