About To Install Original Pro-Jection 4

[aprules2]

I have a 75 Cadillac Coupe Deville with a 500, the carb is shot so I picked up a used Holley Pro-Jection 4. This is the first generation Pro-Jection 4 with the smooth computer not the one with the heat sink. It's non-digital. The original fuel pump did not come with it, I think it calls for 15 psi. I've heard there's a factory GM inline pump that would work to replace it? If not, what pump can you guys recommend. Also, I'd like to convert it to use an oxygen sensor, is the kit still available? Do you guys have any tips for installing it? Things I should look out for? Thanks Guys.

[440roadrunner]

Personally, I would not waste my time. I have and have run a 2D, which I bought used. Even sprung for the optional (narrowband) 02. Soon after I found a used Commander 950 which I ran for awhile (4bbl TBI), and later upgraded it to the Holley HP ECU. I hope to build it all into a multi-port if I live long enough, LOL

There are at least a couple of aftermarket pumps you can buy which work, but I'll be darned if I can recall where I got them. I'll try to find that.

If you do end up playing with this, I would not screw with the original O2. On my Commander 950, I bought an Innovate O2 which has a dash display "gauge" and it interfaces with the Holley. It has both WB and narrowband output levels on separate lines. This gives you the ability to see what you are doing, see what "it" is doing. Also, these aftermarket O2 setups have data logging so you can save a "run" and look at it.

[Danny Cabral]

The original fuel pump did not come with it, I think it calls for 15 psi.

Yes, the TBI fuel pressure can be increased to 18 psi (old style B2 injectors) or 21+ psi (new style Delphi injectors).
Use a 5/32" allen wrench and turn the set screw in the pressure regulator clockwise to increase fuel pressure.

Also, I'd like to convert it to use an oxygen sensor, is the kit still available?

It's still available for the digital Pro-Jection systems (534-54 Closed Loop Kit), but not the analog systems.

Do you guys have any tips for installing it?

Yeah, don't use it.

[aprules2]

Why not? It's not like I'm looking to race John Force, the car is a daily driver. I'm looking for a car that will start easy when it's 20 degrees out. TBI has to get slightly better mileage than a carb, and I shouldn't have to tune it constantly. I know my '79 Camaro with a 305 and a 4 barrel, didn't get the mileage my '89 Camaro with a 305 did. And the '89 was more responsive and had better idle characteristics.

[Danny Cabral]

Why not? It's not like I'm looking to race John Force, the car is a daily driver.

It's funny you mention that, because this particular system is more suited for WOT drag racing, than daily driveability tuning.

TBI has to get slightly better mileage than a carb, and I shouldn't have to tune it constantly.

It's highly unlikely that you'll get this antiquated analog EFI system well tuned, without a wideband O2 closed loop sensor kit.

I know my '79 Camaro with a 305 and a 4 barrel, didn't get the mileage my '89 Camaro with a 305 did. And the '89 was more responsive and had better idle characteristics.

Yes, but that '89 Camaro was an OEM, factory tuned EFI engine. No comparison to what you'll accomplish with the analog Pro-Jection 4 in open loop.

[440roadrunner]

If you get this thing cheap enough, you MIGHT use it for the parts. This is a 4bbl? Does it have the newer injectors?
Danny probably doesn't want to hear this, but you could adapt a different ECU, including Holley, or MegaSquirt.

[Danny Cabral]

This is a 4bbl? Does it have the newer injectors?

Yes, the Pro-Jection 4 is a four barrel throttle body unit.
It most likely still has the older Holley B2 injectors (black round top injector caps).
I doubt it has the newer Delphi injectors, which requires the injector pod upgrade.

Danny probably doesn't want to hear this, but you could adapt a different ECU, including Holley, or MegaSquirt.

I agree with you. I just remembered the analog Pro-Jection 4, isn't even a speed density type EFI system!
No MAP sensor to measure load, no O2 sensor for closed loop correction and no IAC motor for idle control.
It's an Alpha-N type EFI system, which means the Fuel Map is based on RPM & TPS only.
Holley Pro-Jection 4 Manual (← Click Link)

The first fuel injection system I ever owned was the Holley Pro-Jection 4D (6 knob calibration module).
It wasn't as bad as I thought...but I can't imagine using the antiquated analog Pro-Jection 4 system.