Engine Swap

[GMC1971]

Well the 79 is toast. Put a new cam in and found a LOT wrong after the repair. Time for a swap. I was thinking about taking the engine and transmission out of my 1994 GMC and putting in there. How how hard would it be to put a 350 and trans out of a 94 into a 79? The gmc runs like a scalded dog and cruises the highway like a leer jet but the body is just terrible. Would love for the 79 to run that good.

 

[Rusty Nail]

I think that would be cool!

Since you have the other truck...the swap is as easy as possible...I only wonder about the depth of the '79 to accommodate the fuel sender but I betcha that aftermarket parts are READILY available. There will be some type of fuel line business I bet.

Take lots of pics!

 

[GMC1971]

Never thought about the fuel sender but i guess i could alway go frame mounted and keep the old unit in the tank for the gauge couldn't i?

 

[1987 GMC Jimmy]

Were you planning on keeping it TBI or carb swapping?

 

[Rusty Nail]

I assumed OP wanted the TBI, what else would be the purpose? I would switch TO TBI in a heartbeat....that would be so rad in a square....

I don't consider a frame mounted pump a reasonable choice given you have both complete trucks...there's no reason to NOT run 100% of the TBI parts, imo. But like I said, I think the only real "issue" is fuel related, the rest will BOLT UP. Easy/Peesy. It's a great idea.

Somebody has done it, let not your heart be troubled!

 

[GMC1971]

I also want the transmission since its overdrive. Would i have to change the crossmember?

 

[1987 GMC Jimmy]

That’s a fair assumption. I’m on the same page with you there. Especially since it sounds like the ‘94 is bug free at this time. I think the biggest chore is going to be the removal and reisntallation of the PCM and engine harness. That’ll take care of your engine and transmission electronics. The issue with the tanks is the lack of baffling inside the tank to circumvent sloshing and keep the pick up submerged. I don’t think depth is the issue, though. If there’s a good radiator shop near you, they might be able to install baffling, but you’ll more than likely have to get the correct ‘87 tanks. You could also do a 31 gallon ‘87-‘91 Blazer tank. I wouldn’t do external pumps myself. Internal pumps will almost always last longer and work better. If there was an ‘87 truck frame around you with the lines so you could have a factory setup and have the spot for the fuel filter, that would be nice. As far as the transmission goes, I don’t know for certain, but a 9” tailshaft TH350 should be a completely or almost completely drop in slot for the 4L60E.

 

[GMC1971]

Well it sounds like i have a project then. I have to wait until i find something else to drive in the meantime but i think i should be able to tackle it. Against my better judgement, i think i will go with an external pump at least temporarily. I can fix fuel issues later as they arise. My biggest hurdle will be the pcm. Should be simple enough though that 94 suprisingly has very little wiring.

 

[1987 GMC Jimmy]

Yeah, TBI is fairly simple even when GM tacked transmissiom control on there. It should go well.

 

[GMC1971]

Sounds like i finally had a good idea!