need some input

[Greasedog]

Kicking around changing directions in my project truck, and I'm kind of at a loss as to which parts would be best suited for my application.

I'm looking to modify a stock 94 TBI harness to basically a standalone harness, I'd like to also retain the stock instrumentation for the truck while installing this harness.

Truck is an 84 C10 body, on a 4x4 chassis.
Engine is a L31 Vortec replacement crate engine, completely stock with an Edelbrock Performer RPM (noon Air Gap).
Trans is a 94 4L80e with an NP241 behind it with a cable drive speedometer.

Here's where I come into my question of what the best route to proceed is... I've accumulated some TBI parts...

A complete 94 454 TBI setup, originally on the 454 that was in front of my 80e. This is the high pressure, small injectors setup.
Or
Complete 94 2wd 350/60e setup. (I'm told this requires moving 2 wires in the harness to work with the 80e, and only used one VSS, as opposed to one in the trans and one on the output housing if the transfer case-making use of my cable driven speedo easy, plus it's already sized to fit my small block!)

Is one of these harnesses going to be easier to modify to work with my application, or just be overall "better" to work with? Both run on a 7427 PCM, which isn't an issue as the truck the engine is currently in has a modified 7427 in it that I can use.

[Greasedog]

Should probably also add that I have a 350 TBI, ridges removed-stock bore, injector spacer, AFPR, currently on the engine.

The truck will be used as an occasional driver and work truck, as well as carrying a plow.

[billygraves]

.........

[Greasedog]

I actually harvested the entire drivetrain and harness from a 94 K3500 at one point. Sold off the longblock, and the transfer case (driver's side differential while my GM straight axles are passenger side differential -of no use to me.) So I have the entire 454 injection setup, and the trans it left the factory with.

As for the tank issue, I've got an 87 tank I set back specifically for this purpose, though I was going to do a 350/TH400 swap in my 77, using 87 parts. That project is a ways down the road, and I may just keep it carbureted at this point.

I guess my biggest question is, is the 454 TBI system overkill for my engine?

I do like your idea of using one tank as a reserve, rather than using a troublesome switch. It would sure make plumbing a lot easier.

[fastacton]

No, the 454 throttle body should work great on the Vortec motor after some tuning. Just make sure your throttle body adapter is sized for the bigger bores.

[Greasedog]

No, the 454 throttle body should work great on the Vortec motor after some tuning. Just make sure your throttle body adapter is sized for the bigger bores.I don't think my existing adapter has big enough bores. It is a .25" steel plate, and I've had sealing issues with it a couple times. Perhaps going to a thicker aluminum version would be a good upgrade anyways. Who doesn't like more plenum volume? As for the tune, where do you guys think I should start, since this thing is going to be totally different than my existing setup. I've heard just to take the Vortec timing tables and tune the fuel from there using the stock BIN. Should I use a 350 BIN, or start with the 454?

[jim_in_dorris]

Grease, If I was using a 454 TB, I would use the adapter that GM used. All 454 TBI's were mounted to 4 bbl carb intakes. 89428943

I would use the 350 bin, what ECM are you using?

[sturgillbd]

The 1991 454 didn't use an adapter. I apologize for the out of focus pics but here is what the later 454 intake looks like. I also have one of the carb intake adapters.

[Greasedog]

Grease, If I was using a 454 TB, I would use the adapter that GM used. All 454 TBI's were mounted to 4 bbl carb intakes. 89428943

I would use the 350 bin, what ECM are you using?

Jim, it's funny you mention all TBI big blocks being carbed manifolds with an adapter. This one didn't. I funny planned to take the adapter when I sold the longblock. The only issue with using a factory one is my intake is the factory adapter was for a spread bore, and my Edelbrock 7116 is square bore.

Either way I go, I'll be using the same 7427 PCM.

[jim_in_dorris]

I would use a square bore to spread bore adapter, then the 454 tbi to spreadbore adapter. I honestly didn't know that GM didn't use the adapter on all 454's. I plan on using mine with the 454 tbi and the high flow low pressure 454 injectors when I build my next engine for my truck.

[Fast355]

I would use a square bore to spread bore adapter, then the 454 tbi to spreadbore adapter. I honestly didn't know that GM didn't use the adapter on all 454's. I plan on using mine with the 454 tbi and the high flow low pressure 454 injectors when I build my next engine for my truck.

I have a factory TBI to square bore adapter that was on a 405 hp 502 Mercruiser in a houseboat.

[Greasedog]

Are there any advantages over these choices with the Mercruiser piece?

http://m.summitracing.com/search/department/air-fuel-delivery/part-type/throttle-body-adapters-carbureted-manifold/manifold-mounting-flange/square-bore-4-barrel/adapter-material/aluminum

[Nasty-Z]

Are there any advantages over these choices with the Mercruiser piece?

http://m.summitracing.com/search/department/air-fuel-delivery/part-type/throttle-body-adapters-carbureted-manifold/manifold-mounting-flange/square-bore-4-barrel/adapter-material/aluminum

The 17-45 Holley is a good piece , have used many before I started machining my own.

TOM

[Greasedog]

Trans cooler lines. Don't use any rubber hose even the SS Rubber. It fails. Use steel and or Teflon lined SS hose. Parker is cheaper than other brands, if you get a corp discount.just noticed this, dunno how I missed it before. I've got access to a place that can make me heavy duty high pressure hisses in any length and configuration I want. Parker swedged ends, Aeroquip
Triple Crown hoses. I've used these hoses at a 3000psi working pressure on heavy duty tow trucks, with much success. I don't think I'll ever put them through as much stress as we did there, so they should basically last forever.