Sailor77

First the easy question... has anyone done this?

All be it I have an 85 GMC with an 87 TBI system, it is similar to the camaro, and you all are by far the most knowledgeable people when it comes to camaros. I built me an engine for my truck that will surpass the caps of the stock 2bbl tbi. I have a Holley 4di 4bbl 700cfm system sitting here that I want to use.

What problems might I run into?

How much of my stock harness should I remove?

Should I consider using the stock GM computer to run the holley 4bbl tbi?

I want to have my truck running by columbus day. It doesn't have to be tuned 100%, but just to hear it run would be music to my dual exahusted SBC lacking ears.

The engine specs are
330/380 GM crate short block...zz4 crank, zz4 cam, pro topline vortec heads, edelbrock vortec square bore intake.

dimented24x7

iTrader: (2)

Yes, there is a guy here whose running 12's with a holley system.

Running one is certainly feasible, but it requires a bit of knowledge on the users part to get it to work correctly with the stock computer.

I would recommend you use the entire system rather then the stock computer to run the 4 bbl. Converting the stock computer over to run it is definatly not easy if your a novice with computers and source coding. Probably youll want to pick out the ecms wire harness and replace that with the holleys harness

Sailor77

guess I was pretty much planing on using the holley computer and all. I will most likely stick with my intake fuel pump since it is new. Just a little courious about the wiring since it is designed to replace carb, not TBI.

ben73

I have been converting mine to run a 900cfm holley TB. I took it for its first long tuniung drive yesterday. I have a little bit more tuning to do, but overall its running pretty well! I have the idle perfect, cruise is good, but just a bit rich up top. I am still using a 7747, soon to be swapped for a '93 16168625 PCM.

Sailor77

I guess you are one of the few who can get it to run with the GM ECM.
Anyone swapped out the entire set up for Holley? That is really what I want to do. I want to minimize the wiring as well, so I need to know what I can cut and take out.

ben73

I haven't done the swap using the holley ecm, but I would guess you will reuse the wires to the TPS, CTS, IAC, MAP, O2 sensor and IAT/MAT if your car already has one. You will need 2 more pairs for the 4bbl's injectors. I would be tempted to reuse some of the 'spare' wires you have going from the ECM location to the engine bay, such as EGR solenoid and canister purge solenoid etc.. This would assure you a neat job, without having to pull in any new wires thru the firewall.

Sailor77

well since I already have the holley wiring harness I will just use that. I can use the same hole as the GM harness goes thru. Ideally I want to pull the entire GM ECM out and all the wires and start fresh so to say. I dont want to remove anything that the Holley will not replace and give me drivability problems

Sailor77

BEN.. where you in Aussie anyway, I've been there many times

ben73

ahhh, sorry i misunderstood.. i thought you were trying to avoid installing any new wires you didn't have to... If you are going to use the holley harness, it should be a piece of cake!! Have you considered TCC ?? I'm in Brisbane, east coast..

Sailor77

TCC?
Yeah I was there in 98 as well as Mel, sydney, freemantal and one other place.