Vannin' Home Forums General Discussion Generic How To ..... 91 G20 motor swap

Hey dudes,

I just got this 90 G20 that has a 5.7l 350 with 35,000 miles on it and transmission that was rebuilt 15,000 miles ago.

I'm gonna be pulling the motor and transmission out and putting it in my 91 G20 that currently has a 4.3l V6.

This will be my first time swapping a motor on a vehicle. I have a buddy that plans to help who is more experienced then myself. But I still figured it would be a good idea to ask yall for any advice you might have before I do this.

Any tips or advice would be appreciated. I will post pictures once I start doing the work.

Hey LoneStarr, why you pulling out a 350 with 35K on it and a rebuilt tranny, most of us pulled the V-6 and put a 350 in it, Why Man,

Read it again, Sammy.

Hi LoneStar, welcome to the site. Glad you have help. Not sure, but I think it goes through the front? Don't smash a finger, it hurts.

Good it's almost the same year. Both TBI, hopefully. The first thing I thought of was connecting, and compatability of the V6/V8 electronic engine management.

I know Vanner's on here will have way more on this than me.

I would think it's going to be a good if thing you have the donor Van. The ESC module's have two different part numbers for the 5.7, and the 4.3.

My last V8 swap was a '69 327, into a 70 Chevy, so I'm not sure about if all your ignition, sensors, and EFI will be "Plug and Play," boy, wouldn't that be nice...

But if you have both Vans, good wrenching! There eh.

I read it it wrong, you will enjoy the V-8

Just jivin, takes me three times sometimes.

Thanks for the replies.




I am mostly wondering what the compatibility of alot of the parts will be.I plan on pulling the radiator, fan, motor and transmission. Both vehicles are TBI.

Wiring and electronics is something I will definitely need help with.

Definitely plan on swapping the radiator and the hoses from the V8 van. If it were me I would leave the v8 harness hooked to the engine and disconnect it from the van. I would then take the v6 harness loose from the engine and leave it connected to the van. Then go one connector at a time swapping them out. The PCM from the V8 will need to be swapped into the van as wellong.

You may also need to swap the motor mounts. Opinions differ on this. I had to swap them but I went from a straight six to a 350.

Having the 2 vans together, you'll be fine... take everything off of the front, take the TBI units off of the intake and lift from there, get the hook as low as possible - IF you're so inclined, take the intake off and put a taut chain across there...

I put a 350 into an 84 about 5 years ago, was very easy and it was my first van engine swap...

Motor mounts from the 4.3 will probably be fine...