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I have 2 engines. A 302 DZ short block with a crack near the rear main. I also have a ZZ383/425hp engine currently in my '69.
I'm thinking about taking the rotating assembly from the 302 and putting it in the 383 short black.


This would create a 302 inch motor with a roller cam and rockers with vortec aluminum heads.


Would this be feasible? I know it would take some machining work. Has this been done before? Thanks.
 

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A 383 is commonly built using a 400 crank in a 350 block. That means 4” bore and 3.75” stroke.

Your 302 is a 4” bore and 3.25” stroke.

BUT...the crankshaft main journal size is the question. A large journal crank will bolt in, but a small journal one won’t...without special thick main bearings that adapt it.

Then there’s the general build issue of making sure the bores are machined for proper piston fit. Piston and block wear and block honing may already have you at a sloppy fit, not to mention that the block could be over-bored. It could also be that the 302 setup is an overbore and your 383’s block is std bore. In any case it’s not likely to be an overnight bolt-together fest.

Lots of trouble for bragging rights...I’d stick with the 383. If you’re adamant about building it up, get the 302 pistons thoroughly measured to figure out what finished bore size you need, find a donor block to build them into, then swap the heads and cam over when you have a complete shortblock. The leftover 383 shortblock will still be worth something afterwards...or you can swap back if you change your mind.
 

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If its a DZ, it should be a large journal crank. I would find a 350 block and make it into a 302. If its the heads you want, take them off of your 383. You can then sell the 383 short block to fund the 302 build. I personally think you should stick with the 383, but its your car.
 

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If you were to make the swap you’d end up with a hi revving low torque engine. The cam in the 383 may not work well in the smaller 302.

Easier to just badge the 383 as a 302
 

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TQ is what moves you and sets you back in the seat.
HP is how fast that occures.

So, I agree with the above to just dress the 383 as a 302. (done alot actually)
 
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