98 4.3 vortec to 5.7 vortec or 5.7 carb & 700r4

[gmc2fst4u]

Hello gents. Currently having some issues with my 4.3. She has 248k and is wore out and abused, I was debating the idea of throwing a good 350 vortec in its place since i already have a good 4l60e and damn good truck thats worth the trouble. Now im also stumped as what all i need to fully do this. No where has this info on any forums to be give a rough idea. I'm not in no way wanting to ship my computer to have it tuned or anything if thats the case then ill go old school, Meaning throw in a 700r4 and older 350 and hammer on down the road or at least a low mileage 350 vortec carb swapped. Any one have any insights for me? Just wondering is all i know whats all involved in both swaps price is not a concern neither is time.

 

[skylark]

My opinion is just drop another 4.3 in it. Otherwise it is a ton of work to swap to a classic v8. The Vortec with its injection is going to be a replacement harness and computer tune. The v6 uses different frame mounts than the v8. The carb swap requires a different tranny (it sounds like you are aware). The fuel pump will have to be bypassed because of way too much pressure. You will also have to adapt a classic tranny to put out 40 pulses per mile to have your speedo work. You may run into othe minor inconveniences that you can overcome.

 

[90halfton]

In a world of endless opportunities under no circumstances put a carbed 350 and 700r4 in a fi computer controlled truck. There's nothing wrong with those things, but if you're gonna go to the trouble at least trade up, not down. Or, as was said, drop a replacement 4.3 in it and enjoy for another 250k miles.

 

[gmc2fst4u]

boring 4.3 daily no thanks lol and im not paying over 2k for a reman 4.3 when i can throw a reman 350 crate in for 1200 lol dont get me wrong the 4.3 is a decently daily but naaa i think ill stick to my plan throw a 350 carb and 700r4 in or at least a trans controller. I just cant find anyone doing a 4.3 to 5.7 vortec swap any where idk why its not that hard at all. Time consuming im sure cost not to bad. Well see how this all goes i have to do some research more first

 

[df2x4]

You could probably get a good used LS motor and all the electronics to go with it for less than $1200 (And have way more power than a stock Vortec 5.7), just saying. Seems like everyone wants to avoid getting a PCM tuned for some reason...

 

[gmc2fst4u]

nothing worst then dealing with getting pcm sent off tuned then get it back not be exactly right re-sending it then getting it back again then having to re-send it again. I have seen this numerous of times all over the forums and im not down with that lol probably why no one wants to get involved in it. I can get a complete ls 5.3 with harness and computers for 600

 

[df2x4]

I can get a complete ls 5.3 with harness and computers for 600

Man that's a no brainer in my book, more power for half the price!

In my experience mail order tunes aren't all that bad. If you're that worried about it you could always find someone close who would tune it in person on a dyno.

 

[gmc2fst4u]

Is there any good write ups on the ls wiring write up? I have searched looked at a few but nothing that clicks for me. recommend any over the other? I already have a 4l60e which no idea when it will die but probably be cheaper for the ls swap in the long run lol im just thinking is all. Never messed with gm before besides a tbi 305 which was hell on wheels to keep going but i come from mopar side of the world and nissan lol i have great experience with wiring..Thanks to nissans nats system