Help on swapping out 4.3

[Grizzly85]

Any advise on swapping out a 4.3 to 5.7

 

[marks86]

probably one of the easier swaps to do, as long as you understand a 4.3 is the exact same motor as the 5.7 just with two less cylinders, I know right off the bat your gonna need a new fan shroud

 

[MadOgre]

You will need to get a cross member from a V8 truck or build one. I think you can buy after market ones too.

I would ditch the ESC distributor if you have it.

Apparently the stock 4 barrel intake and carb has some good value if sold.

Aside from the cross member I think its pretty straight forward except like Mark said you will need the V8 fan shroud and possibly a bigger rad too.

 

[towjoe]

have to change lower motor mounts and stands on frame. 4.3 sets back further

 

[MadOgre]

have to change lower motor mounts and stands on frame. 4.3 sets back further

You have to move the cross member forward as the motor mounts are attached to the cross member in K trucks.

but you cant reuse the old cross member because you would end up with slotted bolt holes due to the frame being narrower towards the front.

 

[towjoe]

I didn't realize it was a k series not a c series. I swaped the 4.3 out in a 86 c20 4 speed once and had heck of a time because I didn't realize all the lower mounts were different. 3rd try setting it it fit like a glove tho

 

[Qwk]

I didn't realize it was a k series not a c series. I swaped the 4.3 out in a 86 c20 4 speed once and had heck of a time because I didn't realize all the lower mounts were different. 3rd try setting it it fit like a glove tho

What mounts did you end up using?

 

[towjoe]

I used everything off the donor truck and same holes as it. Easy swaps when have both trucks side by side

 

[Qwk]

I used everything off the donor truck and same holes as it. Easy swaps when have both trucks side by side

Crap! I only have my one truck.

 

[MadOgre]

Crap! I only have my one truck.

well I guess you better go get another one lol.

Heck I would have my own square wrecking yard if my wife would let me!

 

[marks86]

from my experience with doing a motor swap having a doner truck parked right next to the truck getting the motor is literally the best thing you can do