5.3 or 5.7 swap into a 4.3 V6? ( 04 silver)

Hippiehead025 · October 24, 2004

can it be done? I know ecm, motor mounts, exhuast fabs and stuff will need to be done, but it cna be done correct? I wanna do this is my new k1500 4x4. - Roger

Cool Zr2 · October 24, 2004

Even though 04's didn't come with 350's it would be the cheapest way to get a v-8 in there because your engine bay is pretty much setup for a 350 more than a 5.3, in fact, it isn't setup for a 5.3 hardly at all.

Your options are:

5.7 Vortec - easiest and cheapest

5.3 Vortec - expensive compared to the first, with less torque and more hp than 5.7 Vortec

5.7 LS1 - Really expensive and install will cost the same as a 5.3 Vortec

Hippiehead025 · October 25, 2004

Even though 04's didn't come with 350's it would be the cheapest way to get a v-8 in there because your engine bay is pretty much setup for a 350 more than a 5.3, in fact, it isn't setup for a 5.3 hardly at all.

Your options are:

5.7 Vortec - easiest and cheapest

5.3 Vortec - expensive compared to the first, with less torque and more hp than 5.7 Vortec

5.7 LS1 - Really expensive and install will cost the same as a 5.3 Vortec

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But my k1500 V6 will allow me to swap in a 5.7 or 5.3 though correct? once i get mounts ecm and wiring harness and such? also whats difference in v6 and 5.3/5.7 mounts? thanks - Roger

Cool Zr2 · October 25, 2004

Its not that easy, if you don't use a 96-99 5.7 350 you will have to make your own fuel lines, get a different fuel pump possibly, the accessories on a 4.3 won't fit a 5.3 so you will have to buy them, I'm not sure but I believe the bellhousing pattern is different between a 4.3 and a 5.3. It goes on. The only down side of a 350 is finding a place (like www.currentperforance.com) to make you a wiring harness.

I am wondering why you didn't but a 5.3 when you bought the truck, the upgrade option would have been a 1/4 of when you might spend now and you will loose your entire warranty. I'm not being critical I am just wondering how come?

Hippiehead025 · October 25, 2004

Its not that easy, if you don't use a 96-99 5.7 350 you will have to make your own fuel lines, get a different fuel pump possibly, the accessories on a 4.3 won't fit a 5.3 so you will have to buy them, I'm not sure but I believe the bellhousing pattern is different between a 4.3 and a 5.3. It goes on. The only down side of a 350 is finding a place (like www.currentperforance.com) to make you a wiring harness.

I am wondering why you didn't but a 5.3 when you bought the truck, the upgrade option would have been a 1/4 of when you might spend now and you will loose your entire warranty. I'm not being critical I am just wondering how come?

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I got this truck off ebay....13k on it, 5spd flairside 4x4 k1500....for 10 grand. Want it for a winter beater, but ima lift it and put sum knobbies on it, and i dont like v6's so......V8 swap is a must eventually...haha, makin fuel lines and such isnt a problem either..... im mechanically inclined, i work on my mustang, chevelle and corvette by myself. i just wanna know any pointers and whatknot for an engine swap that any1 might have, and just makin sure I can swap one in. pretty simple just gettin input.

Cool Zr2 · October 25, 2004

Your 04 is setup for a small block, not one of the ls1 derived motors (5.3, 6.0). So the fuel lines and fuel pump will work with no modding or touching, the front end accessories on the 4.3 will switch over to the 350.

The only issue with a 350 is the wiring, that website I sent you will take your exhisting harness and modify it for you for about 300 bucks, the 4.3 harness takes a little reworking for a 350 vortec.

I'd strongly go with a 5.7 SBC over a 5.3 becasue it is a better motor and the costs on putting one in is going to be a fraction compared to a 5.3 swap.

Hippiehead025 · October 25, 2004

Your 04 is setup for a small block, not one of the ls1 derived motors (5.3, 6.0). So the fuel lines and fuel pump will work with no modding or touching, the front end accessories on the 4.3 will switch over to the 350.

The only issue with a 350 is the wiring, that website I sent you will take your exhisting harness and modify it for you for about 300 bucks, the 4.3 harness takes a little reworking for a 350 vortec.

I'd strongly go with a 5.7 SBC over a 5.3 becasue it is a better motor and the costs on putting one in is going to be a fraction compared to a 5.3 swap.

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