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Old 02-17-2026, 02:58 PM
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PAUL K PAUL K is offline
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Join Date: Feb 2004
Location: Sugar Grove IL USA
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Quote:
Originally Posted by b-man View Post
Side loading of the piston is the biggest issue with the 4.5” stroke, along with the short cylinder of a Pontiac block pulling the piston down out of the bottom of the bore. Short piston life and quickly diminishing ring seal I’m thinking.

To end up with the same 1.57:1 rod to stroke ratio as a stock 455 which ain’t that great to begin with (6.625” rod - 4:21” stroke) you would need a rod close 7.1” long with that 4.5” crank.

Is it possible to put a rod that long into a stock deck block or would you need to go to a tall deck block? I’m thinking there’s no way to move the pin that far up into the ring pack on a stock block.

Makes me wonder exactly how GTO Jones is getting away with that 4.75” stroke in his 571. Which block standard or tall and what rod length?
Your spot on.... 7.1 won't work

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