tbi conversion

[1974gmc]

im looking for any info or tech articles on doing a tbi swap. any info or tips would be appreciated. i did a search on here and couldnt pull anything up

[Russell]

There was just recently a post about converting to TBI, its really not that tough

If you are capable of doing some wiring, and have an engine that has a compatable camshaft, there is no reason why you couldn't have it installed and running in a weekend or two

[r0lf-]

The conversion to TBI, IMO isnt worth it. A carb will get just as good/bad milage and HP. And be more tuneable.

[Bandit76]

I am planning to put a TBI in my 78 this year. Good thing is I will have a donor vehicle. That is probably easiest. All the major players put out aftermarket kits. Summit racing has a wicked catalog for generating ideas.

From what I've gotten from people is that you should know the history of anything used that you get and pay fair for quality new. Shop around if you have time. Someone will read this and post a link for you. It happens all the time. If I find one first I will post it.

My burb has the TBI and it was okay for power. 16mpg poorly tuned. I'm hoping better in a lighter truck with headers and MSD, this and that. MAybe new cam, new chip. Build to suit.

Difference that I found is the amount of troubleshooting you can do with the factory TBI. Piece of wire shorted and you can infer trouble codes. Swap a sensor and away you go. MAP,EGR and O2 are common things to look for.

You need a higher pressure fuel pump to get 9-13 at the injectors. That is one issue I have to get around is adapting my saddle gas tanks with fuel pumps from a late model pickup or go aftermarket and spend extra?? money. No matter what you will be modifying gas lines.

There's is a lot of good advice on here. So, just look at the whole picture and determine cost vs payback. Unless you're ridiculously rich, then strip it, blast it, paint it and spare no expense.

I am looking for more info myself so I will pass along what I find.

Peace

[piecesparts]

It is definitely easier if you have a trashed donor vehicle. Take from one and build the Frankenstein in the other. For the older trucks, the fuel tank and pump issue is a different animal to deal with. Places like Edelbrock offer a kit to set up dual tanks to fed a fuel injected motor, since they sell fuel injected manifolds for older engines. Something to ponder as you approach the changeout.
I have an 84 GMC with a 400+ motor in it and I am running a carb, it does well for the setup and gets 14.5 average MPG. The 91 Chevy that I have (daily driver) can get 20 MPG on the highway, and around 17.5 to 18 in mixed driving. There is something to be said about fuel injection--BUT that is only if you can get the right combination of items. This would include tranny, rear end gears, engine setup, air intake, exhaust, and tire sizes. Changing one affects all of the others.
I am looking at taking my TBI out of my 91 Chevy and put a Corvette TPI motor in to get the HP that the factory forgot to include in their TBI setup. I have been looking at this for quite some time now and I hope to have the bugs worked out before the changeout. The first move is to get rid of the engine mounted cooling fan and go to electric fans, then the old motor comes out and the replacement new one will go in. Hope to gain about 100 HP in the deal, as well as maintain the economy average.

[Bandit76]

I've heard good things and bad about electric fans. The fact that you can turn them off so they don't spray mud all over the inside of your hood and engine compartment is appealing to me. Some say the reliability of a good clutch fan is better than the expense of elctric. But....find a wrecked car and steal the electric fans? I'm thinking about it. Or wait for a Parts-Pro sale at Lordco.

I plan on swapping everything including the axles into my 78, but I want to run an H-pipe setup exhaust with no cat converter and 2-1/2" all the way out with some set of name brand mufflers. Has blue bottles painted red now A little too loud to be firing up in suburbia.

I will try it with the TBI. I'm not in the position to shell out for a new vette engine. Wish I was lucky enough to plan that!

But for the record, the entire TBI system to consider will consist of:

ECM - computer controller. Mounted in cab behind glove box.

TBI, intake manifold, wiring harnesses, fuel pump/sending unit(s), and preferably the motor all this comes on Fuel pump relay, you get the idea.

Sensors in good working order. The computer will compensate if some s**t the bed, but make sure you get all the sensors required to match the input signals of your ECM.

O2 sensor in your exhaust pipe.

Some TBI systems have Air Injection (AIR) and others. So, be wary if you get a partial system out of a truck and find there are pieces missing. Before, I even start ripping mine apart I will take countless photos and mark every hose, because there are quite a few more hoses and vacuum lines involved in the TBI setup. Have a look at one that works and note the pieces involved. A Haynes book is good for basic understanding. A GM maintenance manual would be a blessing.

As mentioned by others, it is a tip to tail event, so get someone that knows more than I do to go over gear ratios and "at the wheel" HP so you don't throw in a s**t mix that drives like it sounds. Revs high and goes slow kind of thing.

I've already told more than I know. Someone will set me straight I'm sure.

Good luck with your project.

Peace

[piecesparts]

I got the vette motor when I purchased the 68 Chevy truck streetrod project. The other guy had purchased it out of a wrecked 91 vette with 29,000 miles on the motor. The motor has been on an engine stand since late 1993. The TPI had been removed and sent to Street and Performance for a refurbishment and it is in the box with new injectors, as well as the computer already set for an aftermarket install. I am replacing the front and rear seals and changing out the flexplate for a bigger one that fits the 91 Chevy truck. It more or less fell into my hands with the deal on the truck and I decided to do something different for the street rod for a motor--I have a 2000 Firebird LS-1 setting around for it.