To Carb or to TBI?

[BigTater]

So first off, hello there! This is my first post on this forum as a relatively new GMT-400 owner though I've lurked around here quite a while. Excited to finally make a post and I hope yall can help me make some decisions on this.

I am currently going through the process of reviving a 1994 K2500 Cheyenne that's been sitting for about 9 years after a botched shadetree rebuild. The original 5.7 lost its TBI setup during that process, and now has a Holley 1850 along with all of the fuel system modifications to get gas from the tank to the bowl reliably. After discovering a hole in the cylinder wall on that block, I sourced a complete(ish) replacement motor that ran when I helped the seller pull it myself. (Came from a 94 c1500 GMC if that ends up being relevant to this discssion). I believe I have everything I need to make it work short of gaskets, but I wont really know for certain till I put it all together, and therin lies my dilema.

I would much prefer to restore the original TBI as I believe it to be an overal superior system for daily use, but at the same time I know for a fact that the learning curve for getting that system to function will be pretty steep and dont want to be troubleshooting crank/no start symptoms on a fresh cam, bearings, rings, etc. Lastly, I have about a month and some change to get this engine from its current state of honed, cleaned and painted to running and installed before I go back to College. I'm pretty torn on how to proceed here, any thoughts?

 

[Scooterwrench]

Manual or automatic tranny? The automatic needs a computer to operate it so that would lean more towards TBI. Manual needs no computer so it would be easier for you to get it running with the Holley seeings all the retrofit has already been done.

 

[BigTater]

Manual or automatic tranny? The automatic needs a computer to operate it so that would lean more towards TBI. Manual needs no computer so it would be easier for you to get it running with the Holley seeings all the retrofit has already been done.

Automatic unfortunately, 4L80 though so at least ill be able to tow without nuking it. I'm glad you brought this up as I was wondering what kind of data that trans needs to run properly. Heard from a friend that it only needs VSS and TPS, and I did notice a TPS attached to the holley (see pic below), so it seems some attempt was made in the past to get needed data to the transmission. Not sure if it actually "worked" though...

One thing I should clarify is that I will eventually be swapping the Carb and intake out for the stock configuration, but as I said I need to be able to drive this thing a ways to school in a month and a half where I have a garage and all the time I need to go through with the swap. Absolute worst case scenario i get it trailered down there but I'd REALLY like to avoid that for obvious reasons.

You must be registered for see images attach

 

[BigTater]

Another bit of clarification I overlooked was that this truck was bone stock until the engine was pulled for that doomed rebuild. During that period, block was decked, bored and stroked to 383. It received a new AGGRESSIVE camshaft along with aforementioned the fuel delivery changes. Other than that, the wiring is unharmed to my knowledge and the computers have not been removed.

I don't want all that performance crap in a work truck, and neither did the previous owner which is why he left it to sit when the dust settled (yeah, he didn't approve any of those mods aside from requesting an "overbore and new rings"... the builder just fired the parts cannon on him!) I just want to build a stock work truck that I can use to tow home more bad ideas in the future!

 

[Scooterwrench]

Another bit of clarification I overlooked was that this truck was bone stock until the engine was pulled for that doomed rebuild. During that period, block was decked, bored and stroked to 383. It received a new AGGRESSIVE camshaft along with aforementioned the fuel delivery changes. Other than that, the wiring is unharmed to my knowledge and the computers have not been removed.

I don't want all that performance crap in a work truck, and neither did the previous owner which is why he left it to sit when the dust settled (yeah, he didn't approve any of those mods aside from requesting an "overbore and new rings"... the builder just fired the parts cannon on him!) I just want to build a stock work truck that I can use to tow home more bad ideas in the future!

Pull that cam and replace it with a good torque cam that will pull to 5000 RPM's. It will make life a lot easier when you decide to go back to TBI. You will still have to tune that ECM for the larger displacement but it shouldn't be a major hair puller.

 

[BigTater]

Looking back through this thread I’m realizing I never really specified that I’m building the donor motor, which was bone stock and running when I pulled it. All of the performance mods were done to the block I pulled from MY truck, and these mods led to it dropping a valve and destroying a cylinder, necessitating a new engine. Sorry for the confusion, still pretty new to forums in general and not the best writer but I hope that makes more sense?

Also after a lot of thought I’ve decided to just bring the engine build back to school with me and not the whole truck, it’s too much to build this motor AND get the truck registered and roadworthy enough for a 400 mile drive all in one month. Plan now is to get parts, build what I can for the next month and then bring the engine and a stand to fire it on back with me.

This way I can do at least an initial break in on the stand and then some time down the road the engine will go in the truck.

 

[Scooterwrench]

Looking back through this thread I’m realizing I never really specified that I’m building the donor motor, which was bone stock and running when I pulled it. All of the performance mods were done to the block I pulled from MY truck, and these mods led to it dropping a valve and destroying a cylinder, necessitating a new engine. Sorry for the confusion, still pretty new to forums in general and not the best writer but I hope that makes more sense?

Also after a lot of thought I’ve decided to just bring the engine build back to school with me and not the whole truck, it’s too much to build this motor AND get the truck registered and roadworthy enough for a 400 mile drive all in one month. Plan now is to get parts, build what I can for the next month and then bring the engine and a stand to fire it on back with me.

This way I can do at least an initial break in on the stand and then some time down the road the engine will go in the truck.

In that case go with the TBI. It should be plug and play.
Good thing they didn't chop the wiring harness out.
I take it you're going to automotive school?

 

[BigTater]

In that case go with the TBI. It should be plug and play.
Good thing they didn't chop the wiring harness out.
I take it you're going to automotive school?

No kidding! I was euphoric when I found the intact wiring taped up inside the harness, given the quality of the rest of the work (a prime example being a missing head bolt replace with an off the shelf bolt of the same size and pitch) I fully expected the wiring to be full of bare ends.

Also nope, I’m just a young gearhead that loves the smell of uncatalyzed exhaust in the morning… Going to school for Civil Engineering actually.

 

[Scooterwrench]

I'm guessing you have good knowledge of the internal combustion engine. Once you get it back in there and running you can get some power and economy out of it by tuning the ECM.

 

[RichLo]

Your on the right path... Try to get back to the TBI, but worst case your an intake manifold swap away from just getting it running and going through the break-in with a carb.