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Discussion Starter · #1 ·
I'm getting ready for my stock 4.3 to go down. It's on the way. I'd like to carb v8 swap it. It's a 96 zr2 5spd. Cant find anything specific on it so I don't know if there's anything different with doing it. And advice is appreciated
 

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time to get cereal
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5,806 Posts
It will definitely be easier to go carb with the manual than an automatic. 4wd is a bit different than 2wd though.
 

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Two tones of terror
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730 Posts
Any specific reason you'd want to convert an EFI truck to carb?
 

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time to get cereal
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5,806 Posts
I'm not sure about the flywheel and clutch assembly, but someone will eventually chime in on that.
 

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Been there Done it
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I've done a MPFI 5.7 swap into a 98 ZR2.
You will need a special 4wd swap oil pan.
For 2 piece seal blocks 55-79:
For 1 piece seal blocks 86 and up use their 1109 pan
Don't know of a pan for the 80-85 because the dipstick hole is opposite side than the 55-79, but it's still 2 piece block.
For motor mounts the only ones that will work on a ZR2 with it's welded to the frame lower mounts are:
Advance adapters 713123
or:
Trans Dapt 7204691
Since the original mounts are both weak and of poor design I suggest you buy replacement 3.1144 Poly mounts from Energy Suspension. The black ones hold up to the heat better than the red. They're both stronger than the originals and have a built in safety loop so that if they should break the engine can't swing way up and break things. Something the OEM rubber ones don't have. You should take a little tin and make heat shields for them.
They will make the engine sit a bit higher in the front. I had to notch the hood bracing to clear the A/C compressor. Of course if you're going with a carb you probably won't want anything modern like A/C.
S10 4wd headers are available from a number of manufacturers. I'm running Patriot coated ones.
One thing to consider is an L31 Vortec 350 96-02. 99-02 are in full size vans primarily, because the pickups and SUV's went to LS engines in 99. Vans in 03. Simply replace your PCM with one out of a 96 ONLY 4wd pickup with a 350 or have your existing PCM reprogrammed as a K1500 w/ the 5.7. Wiring would consist of adding 4 wires and moving 5 to different locations on the PCM. That's it and you have sequential direct port injection. Way cleaner and more powerful than an old carbed 350. The fuel lines even bolt up and your pump will work fine. With a carb you'll need to do some fuel system mods on both ends.
Regarding the radiator. You current one will work with electric fans and recessing it into the support a couple inches. When you get to that point I can help you thru it.
When choosing an engine for a swap it is more important to use an engine that will swap easily than to simply use what you got. That more often than not, will result in a lot more work and more money than necessary. When you are done the engine will likely be 10% of the cost of the completed project.
When I built an SS454 S10 the rebuilt 454 cost me $500. I spent over $5000 total and at the time I worked part time in a junkyard so things like transmisions, rear ends, interior, etc were all free. Also had access to any tool you can image including a complete machine shop for any fabrication needed.
If I hadn't had friends in low places it would have cost twice that much. I did it the hard way simply to prove to myself that I could. Sold it within a year.
You can do that too if you want. It's your truck and your money.
I'd find an L31, based on my many years of experience in the auto trade and having done numerous S10 swaps.
 

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Two tones of terror
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730 Posts
One thing to consider is an L31 Vortec 350 96-02. 99-02 are in full size vans primarily, because the pickups and SUV's went to LS engines in 99. Vans in 03. Simply replace your PCM with one out of a 96 ONLY 4wd pickup with a 350 or have your existing PCM reprogrammed as a K1500 w/ the 5.7. Wiring would consist of adding 4 wires and moving 5 to different locations on the PCM. That's it and you have sequential direct port injection. Way cleaner and more powerful than an old carbed 350. The fuel lines even bolt up and your pump will work fine. With a carb you'll need to do some fuel system mods on both ends.
This. Idk how you plan on using this truck or how much but gas is about to be $5.00 a gallon nationwide. Save the carbs for the old cars that need to be period correct. Considering the poor mileage, additional wear on the engine from fuel washing the cylinders, contaminating oil etc etc I don't see why you would want to go that route. Your year truck can be easily swapped to an L31 with little work or investment. You are going to spend more money and end up reverse engineering everything from the fuel tank to the throttle cable just to make your truck run with a toilet bowl.

An L31 Vortec can be had for around $300 complete from a pick and pull and will run circles around any of the small blocks that came before it. You won't have to change fuel lines, sensors or much at all. It will look like the truck came with it. Just add additional wires to run the extra two injectors.
 
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