93 ext cab short box engine swap

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mhau93obs

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Based off my research my truck is somewhat of a Unicorn. I've gone through rpo codes been and done as much research as possible. It's a 93 ext cab gmc sierra with the 4.3 tbi and a factory 4x4 nv4500. My issue lies with the engine. It's sluggish and I'm concerned about towing with it even with the work ive done to it. Ive put in new plugs and wires, the factory tbi unit took a **** so i went to the junkyard and pulled a unit off a 350 and it runs beautifully right now and has an idle right around 650-750. I'd rather have a little more get up and go in general. I'm not looking to do efi. Based off my knowledge with vehicles i'd like to go either carburetor or tbi as that's what I'm most comfortable around. What sbc options would be the best option, 350 or 383? Should I go LS and toss on a carburetor manifold? What all would the swap entail? Any help is appreciated.
 

evilunclegrimace

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Just to be clear TBI is EFI, A 350 TBI swap would be the simplest in my opinion. You could find all the neccessary parts at a pick n pull.
 

mhau93obs

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Just to be clear TBI is EFI, A 350 TBI swap would be the simplest in my opinion. You could find all the neccessary parts at a pick n pull.
It is but it isn't at the same time. I don't know why but tbi makes more sense to me in that situation as it's closer to a carburetor in the way it's set up. Now as for the computer do I have to get a new computer or is there a way to use my factory computer?
 

evilunclegrimace

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It is but it isn't at the same time. I don't know why but tbi makes more sense to me in that situation as it's closer to a carburetor in the way it's set up. Now as for the computer do I have to get a new computer or is there a way to use my factory computer?
NO, it is EFI it just is not multi port EFI. It does not work like a carb it only vagely resembles one. It would be easier to get the ECM from the truck that you get the engine out of as the PROM and MEM-CAL are different for an 8 cylinder engine.
 

mhau93obs

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So I have found a few cheap 2 piece main short blocks, yes i know not the best option due to being notorious for the rear main leaks, im not too worried about that personally speaking. I've been looking for other tbi 350s but no luck and I don't feel like paying what the wrecking yards are asking. I plan on getting a rebuild kit and completely rebuilding the engine. I know it requires a different flywheel for a 2 piece main. Would I be able to use the same clutch? Or are there any clutch recommendations to work with the older style motor and my nv4500? I've been looking on Google and such but haven't had any luck. Any help is appreciated.
 

Schurkey

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Two-piece rear main is no real problem. They take longer to install properly than the one-piece seal. Once installed properly, and assuming the crankshaft seal area is not damaged...they're good-to-go for pretty-much the life of the engine.

I'd expect the clutch will work fine with the two-piece seal flywheel, but I don't know that for sure.
 

Moofus02

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That shouldn't be a problem. 2 piece flywheel, spread bore intake with tbi adapter i would use ebl elb ? Flash. You have the good trans and it is a stick so you don't need trans control and you can tune to your hearts content with that system. I would put a vortec pump on your sending unit ep381 I believe. If you later upgrade to a 383 it will allow you to tune for that also
 

mhau93obs

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Alright I do appreciate the help. From what I gather the only real difference in the blocks is just the casting for the main seal. So rebuild the engine, get the proper flywheel for said engine and my clutch will bolt right up to it? How much work would it be to just get my system running via carburetor that way i dont have to deal with as many electronics? I have more experience with them than efi. Tbi is fairly easy to understand in comparison to most other efi systems to me. I'd rather get feedback from more people with more experience than just going Gung ho on this. Also I do want to go straight axle swap on it eventually. But that's a whole other story
 
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