Chevy SB-BB swap

[SOLER]

Just want to hear some thoughts. I had a '76 Suburban with a 350. It was a half ton with a 350 transmission with a shift kit. I put a 454 in it, and kept the 350 transmission. I never had any problems with it except it shifted just a little funny. Nothing I couldn't live with. I now have a '91 'Burb with a 350, and am wondering if I can get away with putting a big block in it with the same transmission. It's a 4x4 and just needs more power. I want better fuel economy, and the big block will get just a tad better because it isn't working as hard. Of course, I could just go the distance and put an older Cummins in there, but I don't know if it's cost effective, especially with the price of diesel vs gas these days. Plus the diesel weighs more than a BB, and it's just a half ton.



I don't drive my dually because it doesn't get very good mileage and diesel costs too much.

 

[DodgeWarlock]

You say it has a 350... is that the motor or the transmission? I would assume a '91 350 motor to have a 700r4tranny. (I believe it was also possible to have a 4l80e) The 700R4 will bolt up and would hold up if babied. Later 700r4's were stronger, as I recall starting in '91 or '92. If you plan on heavy towing or pushing it, I would consider either upgrading it or switching to a 4l80e. Is the truck fuel injected? If so you may have trouble getting the factory computer set up to lock the converter. If so there are some kits available for this from b&m and painless wiring. There is also a way to wire the transmission to autolock the converter whenever it shifts into 4th and to shift out when downshifted to 3rd as well as unlock any time brakes are pressed. I did this in a '79 chevy van I had when I converted from a t350 to a 700r4. Just remember that some 700r4's are not as strong as a t350 and will not take the abuse. There are some good sites with info on these trannies out there if you do a little searching.

 

[SOLER]

Thanks for the info

Yes, it has the 700 transmission and a 5. 7 L engine. All the electronics was what I was referring to. As far as it holding up, I planned on beefing it up. The biggest problem these trannies had, regardless of the engine, was the heat generated from the constant shifting from 3rd to overdrive and back. A shift kit and a converter lock kit cure this. I'll also install a deeper pan and a gauge. It already has an aux. cooler.



As for the electronics, I'll do some more searching. Thanks!



SOLER