Im not sure how advanced this is but I didnt want a bunch of guesses.
On a LT1 with .030 overbore what displacemnent will the following cranks give you. And how much modification/clerancing is needed?
3.75".. I assume is for 383ci
3.875"?
4"

 

For starters, this should be posted in LT1 Tech (it's not really that advanced).

But anyway......if I'm not mistaken, the LT1 has a 4" bore stock, like an old SBC. So, a 4.030" bore and a...

• 3.75" stroke = 382.667 cu. in. or "383"
• 3.8125" stroke = 389 cu. in. (my old "383" had a custom machined crank, which measured 3-13/16" or 3.8125")
• 3.875" stroke = 395.423 cu. in. (396??)
• 4" stroke = 408.178 cu. in.

However, beyond a calculator, I can't tell you too much about clearancing or anything. All I know is once you have the crank in place, you have to turn it by hand and grind out each of the places where it comes in contact with the block, and there are spec's on what the minimum clearance should be (which others may know). Also, I can only assume that a crank with 3.875"/4" stroke is a custom aftermarket crank -- mine was a factory crank that had been machined (smaller journals, and offset by 1/32") to increase the overall stroke by 1/16" to 3 and 13/16".

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2002 Z28 - A4, 2.73's, Blk/blk, leather, T-tops, sport appearance package - just bought on June 26, 2002!
1996 Sunfire - 2.2L, M5 - performance mods?? Needed too many to list!! - sold June, 2002
1981 Z28 - 383 stroker, TH350 trans., 3.42 posi - sold August, 2000
1973 Camaro - Dad's & my project in the works - to be built: 355 Chevy, 11.5:1 pop-ups, "camel hump" heads (w/2.02 valves), solid cam, 4-speed.....it should be quick!
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[This message has been edited by Capn Pete (edited July 04, 2002).]