[ponchjoe]

I was thinking of rebuilding the 350 P that I have laying around to put it into my 93 GMC 1500. Has any done this? If so, what did you do for motor mounts etc. I know I would need an adapter for the 4L60.

Any input is appreciated

Thanks

[Schurkey]

You'll be re-routing the wires in the engine compartment harness. Starter is on the wrong side, alternator may or may not be.

Be sure the torque converter will bolt to the flywheel, and the torque converter pilot is the right size for the register at the back of the crank. Depending on the thickness of the adapter, you may/may not need longer engine-to-trans dowel pins.

You'll almost certainly be playing games with throttle lever unless you're using the TBI unit from the Chevy 5.7 engine. You'll need the throttle cable to fit, and also the TV cable from the trans. The early 454 TBI had an adapter that converts a standard Q-Jet carb pad to a TBI mount. Works nice, heated via heater-hose water. Available on eBay or from a well-stocked Treasure Yard.

If the cam was mild enough, I don't know why a Chevy 5.7L TBI, computer, and wire harness wouldn't work on a Pontiac 5.7L--as long as you can find a place to screw in all the sensors. The knock sensor and EGR might be the problem children. I'm not expert enough on the ignition module compatibility--it might be that a 7-pin module and distributor for Pontiac will interface with the GM computer--or maybe not. I hear some crazy stories about the Chevy-style 8-pin modules having various timing curves.

I would be using clamshell mounts, but whether big car or F-body would fit better, I don't know.

[rexs73gto]

It would be nice if you can do it & get the TBI to work the correct way to. That way I'm sure there would be a lot more converted that way as in the past getting a GMC truck you could get a Pontiac engine in your truck depending on which engine you would pick to be in it. My grandfather had a 58 GMC 1 ton dump trunk had a 287 Pontiac engine in it.

[77 TRASHCAN]

My biggest thought was the engine mounts. I've heard of a few folks putting Pontiacs in 87 and earlier pickups, easily, but I was not part of the process.
I believe potentially the way to go would be to have the engine and trans bolted together, and slide into frame with the clamshell mounts bolted to the engine mount brackets, attached to the block. I don't know how much the frame brackets that the clamshell mounts bolt to, can be moved, if at all. If you CAN get all this suitably lined up to work, you may be able to mark where holes need to be drilled to make it happen.

I hope you can make it happen!

[unruhjonny]

I'm pretty sure a local collector did this;
he had (as I recall) an early 90's shortbox(?) converted to a tow truck;
I cannot be sure, but think he swapped over the TBI as well.

It has been a long time since I have seen this guy, or his truck, so please don't chug ahead on my account... But I am fairly confident it has been done.
iirc late model GM truck 'generations' were were 1973-1987 & 1988-1998(?).

[Ben M.]

The frame mounts where a 454 lined up were almost exactly where a traditional Pontiac v8 would need to be bolted to in the earlier trucks and cars, so that's probably a start if you can determine that mounting configuration.

[Blued and Painted]

Why.
There are no sbc available?
A buildable cheby core could be picked up cheap.

[ponchjoe]

Originally Posted by Blued and Painted

Why.
There are no sbc available?
A buildable cheby core could be picked up cheap.

On my engine stand there is but since I'm not a Chevy guy (hence the GMC truck and GTO ownership) I wanted something with more torque for towing. It's just a thought and I would love to keep the TBI, unfortunately it might be easier to put one of the 454 TBIs in it....

[unruhjonny]

Originally Posted by ponchjoe

On my engine stand there is but since I'm not a Chevy guy (hence the GMC truck and GTO ownership) I wanted something with more torque for towing. It's just a thought and I would love to keep the TBI, unfortunately it might be easier to put one of the 454 TBIs in it....

I like the logic.
Truthfully, I'd do the same if I had a half ton.

[Sirrotica]

Converted my 1973 360 AMC Jeep tow/plow truck to Pontiac power and started with a 350 Pontiac, that got swapped for a 455 later on. The torque of the 350 Pontiac killed the 360 AMC. The 455 was not even in the same league. The Pontiac torque was constantly breaking stuff that was designed for maybe half as much torque. Driver error in modulating input on the right pedal was partly to blame too.



The motor mounts are gonna be easy, hooking up the TBI/EST is going to be much tougher. Just using a standard HEI with a well tuned Q Jet is going to be an easier route in this swap.