Looking for Guidance

[Weiant2001]

I have a buddy who is willing to give me a 400 ci from a 1970 GTO. I have another buddy looking to sell me a 4L80E transmission. From what I'm reading, if I want big power on my 94 K1500, the 4L80E is the way to go. And stay away from monster transmission.

My question with those smarter than I am, (I'm a motorcycle guy, starting a truck project for the fun of it) can I put the pontiac 400 into the truck with out throwing a bunch of money and modifications? I'm seeing there is a TBI conversion. I understand from my reading there is a stance for both TBI and carb'd motors.

Thoughts

 

[Rocket Surgeon]

BOP vs Chevy bellhouse pattern is my first thought on a problem.

I believe you can get aftermarket trans controllers for the 4l80e

 

[Hipster]

I'm not sure there are going to be a lot of guys out there that have put Pontiac engines into gmt400's to draw from but you never know....

Will the oil pan fit in there or one is available that will clear. Will pontiac manifolds or headers clear the steering column and everything else. There are a 100 questions to ask. Are the water pump inlets on the same sides as the gmt400 so you can hook the radiator up. Ac compressor, ps pump, alt. and bracketry what are are your plans there? Stuff that bolts to the front of the chevy engine and to the intake isn't going to just bolt on the Pontiac. Those 70's pre-smog heads probably haven't been set up with hardened seats for unleaded gas. Hoses and wiring mods? The list goes on and on.

Just because the engine is/was free doesn't make this worth doing. All the little incidentals you would encounter could go a long way toward a decent small block chevy build that will bolt in with no bs with most of what you already have.

 

[HotWheelsBurban]

I agree with what has been said. This swap would be many orders of magnitude easier in an early square body. When you get fuel injection, computer controlled engine and transmission systems, and the bell housing difference, it'll take a lot of work and $$$ to make this work in a 400 truck. Another thing about the Pontiac V8 is I believe it is a wider engine than the small block Chevy. The 400 platform doesn't have a lot of extra room under the hood, like the square body trucks do.

 

[Hipster]

I believe it is a wider engine than the small block Chevy.

Yes, as in will the exhaust manifold on the Pontiac sit where the steering column is supposed to go? My biggest question, I you didn't hear it for yourself, who's to say that 50 y/o engine doesn't have a fatal flaw that prevents it from running. Froze, overheated, old carbed, open pcv engines from this time period were wore slam out at 100k.

 

[Pinger]

From everything I've read on this thread so far - leave the Pontiac engine.
From everything I've read on this forum so far - grab the 4L 80E.

 

[Spareparts]

About 15 years ago i put a rebuilt 1969 Olds 455 and BOP Th400 into a square body chevy 4x4. Had to change the trans tail shaft, Weld up some motor mounts and have exhaust made.
Was super easy.
If i was 15 years younger i might think about doing your swap because it is unique. Now though if i was going to swap a engine set up into a OBS i would just do what everyone else does and use a 6.0LS or 5.3LS as it is cheap, parts are easy to find and been done a bunch i'm sure.

 

[Schurkey]

I don't object to the Pontiac architecture, but it's gonna be a LOT of work and a LOT of dollars to cram it into a GMT400.

If you have a sense of humor, a sense of adventure, spare dollars, and own a MIG or TIG welder, this is probably do-able. If you don't--pass.

 

[L31MaxExpress]

I don't object to the Pontiac architecture, but it's gonna be a LOT of work and a LOT of dollars to cram it into a GMT400.

If you have a sense of humor, a sense of adventure, spare dollars, and own a MIG or TIG welder, this is probably do-able. If you don't--pass.

There is a TBI fed 500 cadillac in a member of this groups truck. Personally I find a LS more of a pain then the older stuff. I have done a TBI 350 Buick, a 500 PFI Cadillac and a 403 Olds MPFI. Just depends on your fabrication skills.

 

[sewlow]

Like the other's have said. It's probably do-able, but it's gonna take some mad skills.
Just curious. Not that I doubt your buddy, but...
How much do you know about that 400?
Do you know for a fact that it's from a GTO?
When was the last time it ran & did it run well?

Pontiac made a whole slew of 400's with some 'advertised' at near 400hp in '60's musclecars to smog-choked anemic low 200hp versions.
If it really is from a Goat, then my way of thinking is that it would probably be put to better use as a GTO engine.
Deciphering the casting numbers may prove to it to be something that actually is worth significant bucks to one of those Resto-geeks that absolutely, positively gotta have a date-coded engine.
IIRC, Pontiac didn't match the engine numbers to the vehicle's VIN.
If it has some kinda pedigree, get some decent bucks out of it & put those $$$ towards a 5.3.
...which that 80e will bolt up to.
There's also a whole lot more proven support out there with the LS swap.
The Pontiac swap is probably, maybe, more'n likely, uncharted territory.
There could be a reason for that.

This'll help.

Pontiac Engine Codes