Engine swap.

[xcanuc]

Anyone swap out their 4.3 for a V8? My 4.3 has 153,000 on it and it is a little tired. Also I need a little more power to haul my toys.

 

Thanks in advance.

Steve

[mjsmith1223]

What sort of vehicle are you looking to swap into? There's lots of people that have done it with S-10's - one blew (roared) by me last week.

 

If it's your '95 K1500, then I imagine it should be pretty straight forward as they came with V8's from the factory in different trim levels.

 

Mike

Grand Haven, MI

[xcanuc]

Sorry. I should have listed that.

 

So I should be able to pick up a 305 or 350 and it should bolt right in? Would I need to change the tranny also? What about the wiring harness. I have never swapped a motor in a car or truck before but have done in it for motorcycles many times. Any info would be appreciated. This is my daily driver so I don't really want to find any suprises that will delay me if I can avoid it.

 

Thanks again.

Steve

[mjsmith1223]

I'll go up to where my knowledge ends (won't take very long) and then someone else will have to take the baton and run with it...

 

The transmission should just bolt up. GM used the 700R4 and the 4L60E behind V6's and V8's. Computer will probably be different due to 2 extra cylinders and a different cam profile. Not sure if just the computer could be swapped or if the whole harness will need to be swapped. If you're grabbing the computer/harness from a donor truck, just grab it all so you have it if you need it. If you can find a 350, grab that. You'll be much happier than with a 305. Someone else will have to address 4.3 mounts versus 5.7 mounts. I think they might be the same, but I'm not 100% sure on that. The radiators might have even been the same, but you'll need to measure when you pull the donor motor to be sure. While you're there pulling stuff, might as well grab the fan from a '98 if there's one in the boneyard. It's an 11-bladed plastic fan that's much quieter than the metal fans. Grab the Y-pipe for the V8 as well. I'd imagine it's somewhat different than the one that comes off the 4.3.

 

One thing I just thought of for someone else to address: The 4.3 uses a CPI with the fuel line entering from the rear. Will the pressure from the existing electric fuel pump be enough for the TBI on the 5.7? Will the fuel line have to be re-routed? How about return lines and lines to the charcoal canister?

 

Sounds like a great learning experience. Please post progress pics if it's feasible to do so.

 

Mike

Grand Haven, MI

[k1500chevy97]

I wouldnt even consider a 305 , its got a lil more power than the 4.3 but not enough to justify a swap.

if youre gonna do a swap go straight for the 350

[MCourson]

I wouldnt even consider a 305

I drive a 305 daily so yea.

[Colorado Kid]

Exhaust is different from end to end.

Motor mounts are different.

Fan shroud is different.

ECM is different.

The same TBI unit will work, with different injectors. If, as someone speculated above, you have a CPI V6 then by all means look for a '96 or newer V8 doner . . . of course that brings up OBD-II with additional oxygen sensors . . .

Radiator should be the same.

 

Hoses, Fuel lines, power steering lines, A/C lines, oil cooler lines (if applicable) will all require some creativity.

 

Tranny won't need to be changed, but if you have an NV3500 you won't want anything stronger than a stock TBI 350 in front of it, 'cause it'll fail.

 

Long and short is, everything fits and everthing is available because the same trucks exist with V8s, but by far the cheapest and easiest way to get a V8 in one of these trucks is to sell the V6 truck and buy a truck with a V8, especially if you don't have any other transportation. That's not as much fun to dream about, or as educational, but it's a lot less frustrating.