14reamdalton

Hi guys, I have a torn-down 425 at home that I picked up for free out of a barn. I am not all too familiar with olds engines since I am mainly a chevy guy, but I am very interested in trying to build this engine and put it in front of an NV4500 5-speed in my 1980 chevy pickup. After tearing the engine down, the only problem I can see is a spun rod bearing which scored the crank a little. My first question is, would it be better to keep the old stock crank and stroke, or go with a new Eagle 455 cast crank with either a 4.25" or 4.5" stroke? I am looking for more low-end torque due to its surroundings. I am also looking to keep this build on a moderate budget, so there wont be any $2000 bills to have the original crank offset-ground to a bigger stroke. I want the engine to put out 400-500 horse with high torque values. The cylinder walls have surface rust, so I have been looking into a set of .060 stock stroke, or .065 stroker pontiac pistons from KB. Would these changes build a moderate short block that could handle the power I'm looking for? If so, my next step would be to have the block magnafluxed and start machining.

I'm open to any and all opinions. Criticism is welcome !

Thank you,

Dalton

joe_padavano

You'll want a complete 455 rotating assembly - crank, rods, and matching pistons. Be sure the crank has been drilled for the pilot bearing - Olds cranks intended for an AT don't have this feature. Your other problem will be a bellhousing for the larger input bearing holder used on the truck transmissions. Advance Adapters sells a bell for a Buick with the truck trans, and it has the BOP bolt pattern, but it does not have a starter notch on the driver side, so you'll have to modify it.

14reamdalton

Thanks for the information Joe! Will be 425 block handle a 4.5 stroke like the 455's?

joe_padavano

The blocks are nearly the same. There are some potential minor clearance issues in the bottom end that need to be checked and corrected if necessary. Obviously this combo requires the correct rod length and piston height for that stroke.