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1985 GMC "S-15" 2.8 engine conversion to what?


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Totally new to the site, and I apologize if the information I am seeking is already on here somewhere, I have looked....I own a 1985 GMC "S-15" pick-up that's in excellant condition. It has the original 2.8 litre engine, with a new carburetor, and runs fantastic, albeit a moderate oil leak from the rear main seal area that has become an on-going mystery to me. We pulled the engine and attempted to replace the rear main seal, but alas, the leak is just as bad or worse. It's not leaking enough to pull the engine again, but just want more power.

Can someone shed some light on replacing / upgrading my engine to something with a little more power. I've heard so many different suggestions, I really have no idea what to replace it with....I've heard 3.4, 4.2, and a few others I can't recall, but it's all Greek to me. I have been told that the 5 speed automatic transmission that's currently bolted to the engine is the only engine it will bolt to, so I'm thinking I will have to replace the transmission as well with a bigger engine. Guess my main questions are, what is the most feasible engine I can upgrade to? Will I have to figure out how to go from "normally aspirated" (carburetor), to Fuel injection? Will I need another transmission, or can I use the freshly overhauled transmission that's in the truck? I am fairly handy with electronics, and have been working on cars, motorcycles, and airplanes most of my life, and finally have a place to do the upgrade, just need input from you guys, that have been here, done this!

I will continue to run the 2.8 until the crankshaft breaks (my brother tells me it's just a matter of time), as it does run really well, and down right cute sounding when climbing an incline when it downshifts (hilarious!)...Any ideas, experiences, or suggestions will be GREATLY appreciated for this project I'm getting ready to undertake! Love the site BTW!

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Ya if it was me I would swap a 350 in it. There's different kits since it's done so much and there's an endless supply of aftermarket for a 350. If you don't want to go the V8 route you could do a newer FI V6 that are put into smaller truck/SUVs or as a base engine in a 1500 1/2 ton. You shouldn't have a problem finding a good engine from a junkyard. Whatever route you go I would get FI. If anything it's just so you don't have to manual adjust it like you would a carb.

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Ya if it was me I would swap a 350 in it. There's different kits since it's done so much and there's an endless supply of aftermarket for a 350. If you don't want to go the V8 route you could do a newer FI V6 that are put into smaller truck/SUVs or as a base engine in a 1500 1/2 ton. You shouldn't have a problem finding a good engine from a junkyard. Whatever route you go I would get FI. If anything it's just so you don't have to manual adjust it like you would a carb.

Places like Holley, FAST, and MSD make fule injections kits that are self tuning and just take the place of a carb and well essentially are TBI
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Places like Holley, FAST, and MSD make fule injections kits that are self tuning and just take the place of a carb and well essentially are TBI

 

I know, I guess I should have worded it differently and said the engine should just be FI. I didn't specifically mean FI from the factory.

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There are kits to swap a small block v8 in to your truck, I would personally do something like this http://www.summitracing.com/parts/nal-12363230

 

It is the 3.4 and will drop in. It is designed as a direct replacement for 82-85 2.8's

That site says "not available", whatever that means....probably around $1600...Kind of looking for something I can get from a junk yard that would bolt up directly to my transmission (trying NOT to buy another tranny)....Then figuring out the EFI...Somebody MUST have done this route before...Not interested in a 350....So I guess my question is if I find a 3.4 in a junk yard, will it bolt up to my transmission?

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A 3.4 it is then! I understand it will bolt up to my transmission, but still un clear if I should convert to the EFI, or keep the carb....Should I buy a 3.4 from the junkyard that has the EFI, or just swap over the intake for my carburetor? Sorry so many questions, I just want to be sure, so that when I get ready to do this, I'll know exactly what to shop for...Thanks again, you guys are the best! I'll post pics of my little S-15 once I figure out how!

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If you want to stay cheap, keep your intake and carb. If you dont have an issue spending an extra $1500 or so and want better econ and power go with something look into something like Holley's Avenger EFI system

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