So, I'm seriously considering a V8 swap in my '94 Jimmy. I'm at the planning stage at the moment. I want something that appears stock, but I'm hoping to build for about 300 horsepower. I want to use a TPI setup from an F-body, or maybe even a TBI setup from a truck if it's cheap enough. My main goal is a factory look, making it work like it would have from the factory. A cam swap and tune would be minimum modifications, I'm thinking I might have the heads ported and freshened up as well.

I want to stay 1st generation small block chevy because I'm hoping to bolt the 4.3 accessories to the front. An LS1 or LT1 wouldn't allow me to do that. Is this a sound plan?

My Jimmy is a 4x4, and I want to keep it 4x4. In 1994, is the transmission the 4l60 (fully mechanical) or the 4l60e (electronically controlled)? Are the transmission and engine controlled by the same module? I was hoping to keep my transmission and build it up a bit, I suppose that depends on what I have. Could I just get a mechanical 4l60 from a full size 4x4 truck, and bolt it to my NP231? I swapped from the NP233 to NP231 last year and want to keep it. Do the full size truck transmissions have the 5 bolt mounting flange as well?

In the end, I want something that runs like a raped ape. I want to do this as cheap as possible too. Under $1000 total. This is why I want to plan things out to get this setup as cheap as possible. Time is no obstacle. I'll wait around for the best deals possible.

 

Im gonna answer what i can think of in your post. someone else can chime in.

I wanna say in 94' your trans would be a 4l60. Not sure if they are controlled by the same module. I wanted to think its all controlled by the main computer. If you were to do the swap,i think the easiest way is to use a 700r4 from a 88-92 (dont get one from 85' and earlier,they were bad for going out,in 85 they revised it with better design). If you get a 700r4 you dont have to worry about the computer,just a detent cable. If you go with a 700r4 remember to get the 4x4 model. You cant put a transfer case on a 2wd trans unless you completely rip it down and swap main shafts since there is a length different between 2wd and 4wd.

"5 bolt mounting flange" you referring to the bellhousing that mounts to the engine? as long as the donor has a 4.3 or 5.7 it will mount up perfectly. 2.8 has a different pattern. if you go lt1 you need a adapter from Advance Adapters.

Also when you do the swap,you will need a special oil pan so the engine will clear the front diff. Ebay has them for 160 bucks. Search for "s10 v8 oil pan"

Also something to think about. The prom chips in the computer needs to be swapped from the 4.3 to 5.7. Cool thing about these 1st gens (at least the 700r4,4.3 tbi models,not sure about the 4l60/4.3 cpi's etc) is all the computers are the same,BUT they have a little prom chip inside that controls the fuel trim etc. You can swap a 4.3 and 5.7 prom chip and it'll work. Like i said this applies to the blazers that come with the tbi and 700r4. I cant confirm it with the electronic trans.

 

Thanks for the insight. By 5 bolt mounting flange, I meant on the back of the transmission where the transfer case bolts up to the transmission output shaft. The 4.3 Blazers have a 5 bolt circle that runs into the transfer case, where I'm not sure what the full size trucks had and what transfer cases they used.

 

Ahhhhh! i see what you mean. As far as i know the 700r4 transmissions in the blazers and the full size trucks are the same. BUT the truck transmissions do have more clutches since they will see more abuse. Or at least ive been told that by several people. Im pretty sure the trans housings are the same.

 

Kinda makes sense...I believe the 5 bolt NP233 and NP231 were built to fit GM transmissions...wouldn't make sense for GM to build a transmission for that transfer case when there was a 6 bolt case used in the Jeep products already. It would make sense for them to design a t-case compatible with the GM trans.

I'm thinking i might try to seek a full mechanical transmission out..maybe find one from the junkyard. I'll have to find out how much they run...if I can keep mine and rebuild it myself I might want to do that. My trans has about 130,000 miles on it, as it was replaced under warranty a while ago. I might want to put new clutches in it but it shifts great at the moment...a little soft but no slip. I can't see me putting anymore than 3,000 miles on the truck per year so if I can get 10,000 miles out of it that's 3 more years I don't have to put money into it. I've rebuilt a couple autos before (and they worked after!) so I'm not really afraid to take it apart.

 

Im terrified of rebuilding a transmission. My father scrapped a minivan and had a extra blown transmission for it and i decided to tear it apart to see whats in it etc. Holy cow it looked confusing. Im good with motors,diffs,fuel pumps etc.but a trans rebuild? no thanks.

 

I never rebuild a trans or an engine

i do wanna rebuild a 350 for my moms truck but im afraid to do so

im going to get a block with the heads and every thing inside her even with timing cover just need to replace the rest of the engine on the block

but im handy at fixing common problems on an engine

i dropped a few transmissions also

 

I don't rebuild transmissions every day, but I went to a tech school out of high school where I learned how they worked. There's an order to everything, and the GM autos aren't particularly hard. I have a few GM shop manuals that would be helpful too.

I figured out I have the electronic transmission (4L60e), since I have no Throttle-valve cable under the hood, totally forgot that was a dead giveaway and popped in my head while I was going over the truck. Plus I looked over the window sticker, yes I still have the window sticker, and it says "electronic 4 speed overdrive transmission" right on it. Dead give away! haha

 

Another way in telling is look on the side of the bellshousing and it'll have a RPO code MD8 or M30. MD8 is 700r4 and M30 is 4l60e. how do i know all this random stuff? Breaking things! Not kidding. Best way to learn things when you are pressured into it lol

 

dam how many bell housings did you break ?