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Greetings!
Not sure I'm posting this in the right place. But I have a 1991 S10 Tahoe trim. Our family has had the truck since new. the 2.8 ltr engine and the 5 speed manual transmission. The engine has 300k miles and is struggling to keep up, even in a good headwind. I would like to keep the truck and change out the engine. The truck has always seem under powered so I would like to go up to maybe the 4.3. I'm not new to engine swaps so I know great ideas can be full of deal brakers unless you get a true understanding of what makes sense. So, I would be very grateful for input you all can offer.
1. Is the 4.3 worth the extra work and money (your opinion)? What 4.3 would fit my 91?
2. I am assuming my transmission will NOT fit the 4.3, is that true? If not can anyone tell me the 5 speed manual that goes with the 4.3?
3. Are there kits to help with such a conversion? brackets, mounts, chip (electronics), etc? Or, is it a figure it out as you go thing?
4. Can anyone recommend where I would buy this engine / transmission?
5. Am I better off just going with a rebuilt / newer 2.8 and be done with it?
6. Is there a website or reading material that I should pursue that would help with some of these questions.

Ant thoughts or insight is greatly appreciated

Bill Laswell
 

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Bill, surprisingly there are more parts, kits, etc to swap in a SBC than a 4.3.
Because there are so many little things that are different the best way is to find a wrecked or rusted 89-95 Vin Z 4.3 S10 and park it beside your 2.8 truck and start swapping. The only wiring you'll need to do outside maybe lengthening a couple sensor leads would be to put a 91 4.3 5 speed chip (PROM) into your current computer. The strongest S10 trans to put behind the 4.3 would be an NV3500. Not the greatest 5 speed ever made, but that's what GM put behind later 4.3 and 5.0-5.7's. You don't want one out of a full size because 1st gear is too low.
Some guys have built the 2.8 or swapped 3.1-3.4's. Can be done but you have to be aware of the subtle differences in those 60° V6's from year to year.
Personally I like the torque of the 4.3. That takes cubic inches. Most folks are happy with the performance of the 4.3. Except those of us who are addicted to POWER.
 

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I have the nv3500 from a fullsize behind a mild 77 chevy 350 in my s10 1st gear is low but theyre stronger than they get credit for they will bolt to a early sbc a 4.3 and newer ls v8's with the right flywheel and crank spacer
 

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Awww..you ain't got shit!
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The 3.4 swap is definitely a good swap but swapping in a 4.3 on a 91 isn't bad either. If it was early 88 or older I'd definitely would have recommended against that due to firewall mods that are necessary to fit it. So much that after all the effort, you'd be like, "I could have had a V8!!" But honestly, I don't like V8 trucks because they're MUCH harder to work on, and most of them are hacked up, overheating and ill driving deathtraps.

One thing to consider about tswapping in the 3.4 vs the 4.3 is that you can reuse basically everything already on your truck and when it wrenches, a 3.4 is a LOT easier to work on. 4.3 is a much tighter fit.
 

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i have more room than most v6 trucks with a 350 in a 97 s10 , if you route things right its cake to work on just depends on what u go with and what suits your budget and how u put it together
338583
 

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Easiest way to not have a death trap is to put it together corectly
Don't be getting all offended. Your build looks nice and done right....

The point I was making is that more often than not, most people's V8 trucks are hack jobs and way dangerous. My uncle and I built one of these in 1989. Mostly from scratch since there weren't any mounts available or really any info on this. Was it fast? Yeah....was it fun? Yeah! Was it safe? ? No way.... It had an Isuzu 4cyl in it from the factory. The motor was too heavy for the suspension. The front end was worn out and it handled like a turd and let's not even talk about driving it in the rain. It also had cooling issues. So what I'm saying is that unless you are really diligent, and/or have the money to do a proper install, upgrading components etc, you get what my uncle had. A fun, fast, ill handling, and overheating deathtrap. Incredibly dangerous if not done right. And as I recall, (and this may have been due to his install) he had to notch the frame for the starter to clear, and changing one with the engine in the truck? Almost impossible. But his truck was a hack job too.

Also noted that your truck doesn't have A/C which gives your installation a clean and uncluttered look and and lots of room vs an A/C setup. Whether your truck actually has more room that a V6 truck is debatable especially since the OP's truck is more than likely equipped with air conditioning being a V6 truck in 91 and probably wants to retain that. No offense either, I don't know how your truck wrenches, but I guarantee you it's harder to work on than my 3.4 equipped truck even with A/C in my truck there are zero clearance issues. That's exactly why I didn't do this to my truck. With the modifications on it it's about as quick as a stock 305 and it wrenches like stock...because it mostly is stock shelf parts from the GM parts bin.

Again...no offense. Not trying to come off sounding like a prick. Just an observation.
 

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None taken man, i guess what im trying to say is if you take your time it can be done safely. but i too have seen some pretty botched builds lol
 

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If you want a big project, upgrade to 4.3/v8. If you are looking for little project, tool around on truck, go with 3.4 conversion. If you want to drive truck tomorrow swap out with 2.8.
 

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If you want a big project, upgrade to 4.3/v8. If you are looking for little project, tool around on truck, go with 3.4 conversion. If you want to drive truck tomorrow swap out with 2.8.
I think I spent about $4000 on my truck doing the 3.4 conversion. This was a $2100 crate engine and basically replacing every other component under the hood. And I mean everything was replaced. I figure to do the same thing with a 350 and do it right, I'd spent probably 50% more than that. it was totally worth it though. I like driving it more than I do working on it constantly which is why I decided I'd go that route. Today a V8 swap is LOT easier than when my uncle and I built the deathtrap in 1989. You can buy shelf parts of varying quality. One thing I also advise against on a V8 swap is that it's not an overnight build for most people. So if it's a daily you'd better count on fixing that 78 Pinto on flats in your backyard to get you to work for that time.

I don't think doing a 4.3 swap would be too bad if you had all the components, ie a rusted out good running donor truck, to swap from and as long as the truck was 88 or newer you'd be good. Later 4.3s are certainly better, but there would be more hurdles but could be done. I think if you got reasonable skills you could do this in a weekend IF you had a donor truck.

Biggest hurdle is proper tuning on the 3.4 swap if you are EFI like me. There's no "tune" for it out of the box since that combo never came together with a 3.4L with a TBI system sitting on it. But as far as ease? Drop it in, use your existing components and you're rolling. With proper fueling the truck can run REALLY good. Mine also has headers and custom exhaust. It's not "fast" as much as it is just really strong and torquey. Lots of low end power. I'm guessing somewhere between 190-200 hp which is certainly 4.3 territory. I should dyno it sometime.
 

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I bought my 97 for $2,100 got a junkyard trans for $350 have about $900 in the v8 350 that i have bored over. 30 with summit cam kit and intake bought a used 750 eddlebrock carb for $100 had 50 miles on it was practically new and have $300 and some change in clutch new slave and flywheel so. yes if you buy a crate engine and all new parts im sure that you would spend a lot more than i did , but it depends on what you can do yourself at home i installed all the bearings and cam and pistons and gaskets myself because i have the required tools everything besides the block machine work. and it cost me $200 for block being bored. and the piston kit for it was $300 with the cam and lifters and gaskets. So i know what i spent and you can build a mean 350 for the price of a crate v6 i spent $4250 and some change on the whole truck and swapping it to a v8 . Not counting hood and wheels and tires and such.
 

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  • I agree with jimmykicker tho what ever u plan on swapping into that thing make sure u have somthing else to drive in the meantime lol never know what u may run into
 

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I did a similar swap as JK...
I bought a junk yard (Upull) 3.4 out of a 95 Camaro. The engine cost me $125 with a core. Would have been $25 more without the core.
I spent way too much on making it go fast(er) though.
If I had simply bolted it in the place of my 2.8 (which was overheated so badly coolant ran out of the exhaust), the whole job would have been under $500.
I added a new timing chain (true roller) and gaskets, bought a new clutch kit and other stuff. It would be a relatively inexpensive and easy swap.

I also added a big cam and lifters, roller rockers, Eddy/Holley intake, Mallory distributor, headers and big azzed exhaust. This blew the bag out of my budget but I had a ton of fun doing it and the truck runs mid to low 14s. It also sounds amazing.

So… adding to this thread, a 3.4 is not too hard to find, and is a direct bolt in. Since your truck is a 91, everything is a direct change over - from the 5 speed to any options you have.

JK bought a crate engine - no longer available. Many upulls offer these engines at a reasonable price.

You can usually tell if an engine is ok by pulling a valve cover and seeing if it is clean = good maintenance. Mine was spotless.

The only draw back I can see is running the TBI in stock configuration. It is way too lean for the 3.4.
JK can offer lots of good info since he went back to TBI from a carb intake - that is... if you go this route.
You could do the conversion in one or 2 days depending on your level of skills and assortment of tools.

If you do go for it, post pix and progress. It's always good to hear about success.
 

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GEARS described the 3.4 with the 2.8 TBI as "gutless". I don't have personal experience with it myself. There is some tuning required no matter how you go on this, but it's not insurmountable at all. Probably find someone to burn you a close enough chip.

4bbl and Holley on the Edelbrock intake isn't bad either. I had that on my truck for a bit too before I put the fuel injection system on it. I like the TBI in that it's easier starting and less mechanical stuff to give trouble, but that's just me.
 
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