hey guys, i recently bought an indy aluminum low deck block. what is the most stroke you can put in this thing. i have a 4.3 stroke (bb chevy rod) but i know of a 4.4 (bb chevy rod) crank i can get my hands on. this block has stock cam location. what would you do? i have to get a custom piston built either way.

I've heard of a 4.5"x4.5" low deck 572 so go for it!

I have a 4.375 stroke with a 6.535 rod in a 4.500 bore in an low deck Indy block. Be sure to check the clearance of the piston skirt to the top of main web. Mine hit and I had to notch for clearance.

What pistons are you running?

what are the weight savings using the alloy low deck?

Diamond

Indy claims the block weights 133 lbs

I had to notch my block the same way, using a 4.25 stroke crank.

On our 4.25 stroke / 6.535 / 4.5 bore the bottom of the pin bosses hit the crank throws also. Dont forget to check that.

i had a 400 block with 4.3 stroke and 6.7 rod everything cleared

Weight savings on the block alone are from 90 - 100lb.

R.

I think I have some of the dimensions at home. They didnt hit on all counter weights but a few and not the full length of the weight. There were "high" spots on a few counter weights that were an issue. Instead of removing the crank and cutting down counter weights and rebalancing we manually removed some material from the pin boss bottom side to clearance. Worked fine but an area to check for sure.

A 572ci low deck is old news.....

PlumBad,
Did you have clearance at the pin boss (yellow)?
From your pictures, it looked like the block interference was at the red area.
Do you know what the crank counter weight dia (or radius) was? As you can see from my calcs, somewhere around 7.1"-7.3" dia is typically needed and most cranks will come between 7.32-7.5. My Callies 4.250" crank came cam cut to 7.32 where it approaches the piston at BDC, but larger at the leading and trailing ends of the counter weight. But I cut mine down to 7.1x dia for balancing.

Jim, sorry I do not have any of the dimensions you asked for. The pin boss cleared fine. The interference was a little farther down the curve of the skirt. I don't know what the counter weight diameter is either. The crank is a Crower and when we ordered it they asked for the rod length we were going to use to cut the counter weight. The tag that came with the crank says CWT Cut for 6.536 Rod C-C. Sorry I couldn't be of more help.

OK.
You have more stroke so I don't know if it is the added stroke, the piston skirt design, or the Indy block.
I do remember the builder I ordered my pistons from (the smart guy between me and Diamond) told both me and Diamond to not notch the bottom of the bores so that the piston could have a little more skirt for stability. And it didn't hit the bottom of the bore/cylinder (block) with 4.250" stroke.

I have compared various pistons with ~1.32 compression heights and the skirt length can vary a bunch (2.38-2.755). But the transition from the piston boss to the skirt can vary also. Your experience taught me one more thing to consider when ordering all the parts. I just don't know if the KB cylinder liners for their low deck is longer than the Indy low deck.

I didn't see any clearancing at the bottom of the cylinder from the top, but the attached view when I did the mock-up at BDC seems to show a KB relief at the blue arrow?