I will be attempting a v6 to v8 swap 4.3 to 6.0 thats why i want to use everything from the new engine. I found the info below on a different forum so i figured i would attempt it. I got a killer deal on a v6 silverado and a good price on the complete 6.0 so if i could get this to work i will have invested alot less than purchasing a truck that was already equipped with a v8

my truck is the same year model as below.
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I see this question come up alot on this board and others, so I thought that my real world experiences would help out anyone considering swapping a NBS 4.3 to a NBS v8.

Truck:
2001 Silverado base model reg cab

Stock Engine/tranny:
2001 4.3 V6 / 4L60E

New Engine / tranny:
2001 LS1 5.7 V8 / 4L60E

I bought the LS1 minus a couple of key items: Wiring Harness, Alternator, A/C compressor, and Electric fans. Know from the start that all this info, unless otherwise noted, works for swaps from the 4.3 to 4.8/5.3/5.7.

Now some comments always seem to come up when people ask about doing this swap:

Question:
I'm swapping to a 4.8/5.3...Do I need a new wiring harness?
Answer:
Yes.

Question:
I'm swapping to a 5.7 LS1...Do I need a new wiring harness?
Answer:
Yes.


Question:
I'm swapping to a 4.8/5.3...Does the wiring harness have to be custom made?
Answer:
No. any stock wiring harness from a 4.8/5.3 will work fine and is fairly priced at about 400. the 5.7 wiring harness will not work, though. will not plug into the truck.

Question:
I'm swapping to a 5.7 LS1 and using LS1 accessories...Does the wiring harness have to be custom made?
Answer:
Yes. due to the location of the alt and the injector plug, a 4.8/5.3 wiring harness will have to be modified to fit. A custom made wiring harness would be easier to use here.

Question:
I'm swapping to a 5.7 LS1 and using 4.8/5.3 accessories...Does the wiring harness have to be custom made?
Answer:
No. any stock wiring harness from a 4.8/5.3 will work fine and is fairly priced at about 400. the 5.7 wiring harness will not work, though. will not plug into the truck.

Question:
Do I need to change out my radiator?
Answer:
No. the 4.3 has 28" radiator like the 5.3. but it's not a terrible idea to upgrade.

Question:
Do I need a new PCM?
Answer:
No, the 4.3 PCM can be reflashed. but if you search for it, you can find package deals of used PCMs and wiring harnesses for around 300.

Question:
I'm swapping to a 4.8/5.3...Do I need all new belt accessories?
Answer:
Only have a partial answer here...but NO, not all of them.

Question:
I'm swapping to a 5.7 LS1 and using 5.7 bracketry and intake...Do I need all new belt accessories?
Answer:
YES. you need all 5.7 accessories.

Question:
I'm swapping to a 5.7 LS1 and using 4.8/5.3 bracketry and intake...Do I need all new belt accessories?
Answer:
Only have a partial answer here...but NO, not all of them.

Question:
Do i need to replace the Fuel Pump?
Answer:
No. it is the same part.

Question:
Will the driveshaft have to be modified?
Answer:
No.

Question:
Will the stock intake system work?
Answer:
No. I'm having to buy an aftermarket intake system to get this done.

Question:
Will the stock tranny work?
Answer:
This is a big question. the stock tranny WILL work. the bell housing is slightly different, but will mate up to the 5.7

Question:
Will the stock engine mounting locations work?
Answer:
no, you'll have to secure some 4.8/5.3L mounts and registers.

Question:
Will the stock exhaust system work?
Answer:
No. you'll either have to remake the entire system or get a 4.8/5.3/6.0 system.

so...if you are considering a swap to a V8, here's what you need:

swap to a 4.8/5.3:
complete engine
belt accessories brackets
4.8/5.3 engine mounts
4.8/5.3 wiring harness
new exhaust system
4.8/5.3 intake system
new PCM or reflash 4.3

swap to a 5.7 LS1 and keeping 5.7 intake and acessories:
complete engine
belt accessories and brackets
4.8/5.3 engine mounts
custom built wiring harness
new exhaust system
new PCM or reflash 4.3

swap to a 5.7 LS1 and using 4.8/5.3 accessories:
complete engine
belt accessories brackets
4.8/5.3 engine mounts
4.8/5.3 wiring harness
new exhaust system
4.8/5.3 intake system
new PCM or reflash 4.3

So as you can see, the swap from a 4.3 to a 4.8/5.3/6.0 is not the nightmare everyone seems to make it out to be. with everything that swaps over...I see nothing wrong with dropping in a 4.8 or 5.3 even....you can get them cheap if you look. swapping to a 5.7 requires a bit more seeing that the belt accessories don't swap.

 

what do those engines run for?

 

got my 2005 complete with 3 WHOLE MILES on it for 2000.00 with the frame mounts and ls1 fans from a 2002 ws6 Trans am

 

if the fuel rails were swapped also, then you're good.

 

Nice! Sorry about my prevoius post, I assumed you were swapping a V8 for a V8, but it sounds like you already know most of what you are doing. As for the flexplate, you may want to verify with someone, but to the best of my knowledge all of the newer 4L80E flexplates are 6-bolt, 11.5" diameter bolt spacing. The 4L60/65/70E flexplates are 3 bolt, 11" diameter spacing. If your new engine was mated to a 4L80E you will have to change the flexplate out. BTW, the one I have is the "dished" type. You might also be able to use the one off your 4.3, I dunno what those ones look like.

 

that sounds fishy. i read somewhere else that someone paid close to the same amount for the same setup as you with the same exact miles. i wonder if ppl are bullshitting when they are selling youguys the setups

 

I wonder that, or maybe it is due to the whole Katrina thing, maybe companies have pulled the motors on some of those vehicles, and just have a crapload of them to sell?

 

I bought mine under the impression that it had "less than 100 miles on it", and believe me, it probrobly didn't have 10miles on it. This wasn't my first big job, and I wasn't born last night. It HAD less than 100 miles on it.

 

Nope, Schram Auto is the s*** i was suppose to get a 2002 with less than 1000 miles but that motor wasnt as complete as i wanted so after talking with a few guys over there, Reed was able to give me a 2005 100% complete for the same price. Then i paid a wopping $55.00 on some 2002 ws6 E-fans..
Badmofo actually informed me of these guys awhile back.Schram Auto has nothing but good reviews from buyers.

The motor i have could go for 2750.00 thats what an engine like it is going for on there site.

also they put on the older intake free of charge (truck intake setup)

so far so good, ill let you guys know how everything turns out with the motor, Friday at the latest its scheduled to come on thursday.

 

s10xtreme dude paid the same with the same mileage and it also came from a cargo van


sharms gets all the GM mishaps from the plant