I realize this probably belongs on the engine swap forum, but being TBI, I figure you guys would probably know a little more about my question.

What exactly would be involved in swapping out the 4.3 v6 for a 350 tbi in a 94 fullsize? I found the perfect truck to buy, but it has the 6. Im wanting to put in a 350 tbi. As far as the sensors, comp., wiring harness, and acc. brackets, etc. what can be reused and what will I need to get? What exactly do I need to do to make it run right, and look like a factory install?

I was planning on upgrading the intake, tbi unit, adding headers, and replacing the engine even if I got a truck that came with the 350, so these parts are a given no matter what, but what else will this swap require?

 

well a 4.3L v6 is really just a 350 with 2 cylinders missing so it should be a really easy swap. Engine mounts, fuel pressure gauge, 350 knock sensor, 350 injectors..... I can't say if the comptuer would be the same. you could ask the dealer. Maybe you'd just need the 350 chip.

 

Yeah, the 7747 ecm controled the 4.3 and the 350 at one point, just needs a chip, that's IF you've got the 7747 ecm.
Pretty easy swap, just need to do exhaust work, all sensors are the same. It's nothing that would require special tools or parts.

 

check what kind of rear main seals the 4.3Ls have so you can get the right 350 that won't have you buying different flex plates or clutch plates and stuff.

 

Not directly related to the actual engine swap, but you may want to look into different front coil springs also. Being a truck, you may only see a 1/2 - 3/4" drop from the added weight of the engine, or more if it's a 2WD.

The actual weight of the two engines may be more than you realize by the time you add the weight of the ex. manifolds/headers, added coolant, added oil, etc. Those things tend to add up fast.

AJ

 

things you will specifically need.
1. 350 injectors
2. front coil springs fro a V8(the 8 is heavier than the 6)
3. a chip from a V8 truck, i think hte ecm's were the same, but you should check that too.
4. new motor mounts(just a good idea while it is out)

your wiring harness and sensors will all be the same.

later
tim

 

Well thanks for all the speedy replies, but the more I think about it I will probably just wait until I can find a truck I like with the 350 already in it. Even though I will still swap a new crate engine in it, just being able to reuse most of the misc. parts from the original engine will make it more than worth it. All of those little parts needed for the 6 to 8 swap add up quickly, especially when added to the "unexpected" costs that always arise when doing a swap.

 

I don't know, I think if the cost difference between the v6 and v8 truck were more than $500, I'd go with the v6 IF it had the TBI and the 7747 ecm. Since you're planning on swapping in TBI and a crate motor there is no reason to get the v6 unless you plan on reusing the exhaust manifolds. If that were the case, then yeah, get a v8 so you don't have to change the exhaust and front springs.

 

So how will I know if it has the 7747 or not? It is a 94 with the vortec 4.3 V6. Is there a place I can check for the comp. model number? If it isnt the 7747 could I just swap out the comp. and use the same wiring harness?

As far as the exhaust manifolds and front springs go, I was going to replace them anyways (headers and lowered springs). The thing I was mostly concerned about were the big things like the radiator and the acc. brackets...and Im assuming the tranny is the same 4L60 as the V8s but Im not sure.

Well now you got me thinking about doing it again. Please keep the suggestions and comments coming.