4.3 to 5.7 conversion

[olblue91]

hello fellow bow-tie drivers. i'm new here and would appreciate some tips from some experienced vets. i'm interested in making an engine conversion. this is what i've got:

'91 c1500
4.3l with manual tranmission
2 wheel drive

this is my donor vehicle:

'92 c1500
5.7l with auto trans
2 wheel drive

i'm interested in taking out the engine and radiator, and putting it in my '91 (replacing the v6 with a v8). i wish to keep my manual trans. other than the engine, i plan on replacing the computer (behind the dash). i have questions, though.

1. does the computer control the trans? if so, will the donor computer not work, since i plan on keeping my manual trans?
2. will the manual trans bolt up to the 5.7l?
3. will i need more than just the engine, radiator, and computer?

any tips would be greatly appreciate. j2p2m@yahoo.com

thanks for reading,
john

[TMRuiz]

The computer for the trans and the engine are two seperate computers I believe, But yes the engine should bolt right up to that tranny because the 4.3 has the same bolt pattern as the 5.7. Now for the chassis I'm pretty sure you are going to have to change the main cross member thatthe motor mounts bolt up to. The good news is that the bolt holes for the V8 cross member is already there. So with doing this swap your also going to have to deal with the exhaust and the wiring harness, but you should be able to get the harness from your donor. It gonna take a good weekend working hard at it to get it all done. My brother and I did that same swap on an 85 C10. Since we didn't have to deal with computers it took us about 12 hours to do the complete swap, but what really saved us alot of time was we had the entire front cap off of the truck. I hope this help butat the same time I hope I didn't scare you away from your project. Good luck and let us know how it turns out.

[2COR517]

Pulling the front clip will be a huge help. Doesn't take that long either.