New To EFI Need Some Advice

Hey everyone, I am a mechanic with prior experience working on fuel injected cars but have never built my own system. I have a 75 Cadillac Coupe DeVille with a 500 and a TH-375 transmission. I drive the car everyday and the carb is tired and and now I'm only getting about 10mpg. Rather than rebuild the carb I'd like to up grade to a TBI set up. A while back I bought a first gen analog Holley Pro-Jection set up but it didn't have the O2 sensor set up. The module for the original projection to accept an O2 is no longer available. So everyone has told me it pretty much worthless. However the Throttle body is good for 700 CFM and is a 4 barrel. It has one TBI injector per bore. It seems the GM TBI swaps are very popular however the 454 throttle body is kind of rare and very over priced. I wanted to know if I could use the Pro-Jection 4 Barrel throttle body and tie the 2 left injectors together and the 2 right injectors together and have the GM computer drive them ad if it was the 2 barrel 454 throttle body? Or would the added load cook the transistors that drive them? I like the idea of the 4 barrel because its free, plus it should yield better performance over a 2 barrel. Smaller bores so more velocity and all, plus more CFM. If not what can I do?

happen to know what kind of resistance the injectors have? that will determine what you can do for injection schemes.

The Holley TBI injector are not known for their reliability, as in they aren't very reliable at all.

Yes a Delco ECM will be able to run it, IIRC they are low Z so you will have to run them in series (a friend is currently doing something similar on his car with a custom 4 bbl TBI, and it's been running fine for a bunch of years).

I'd be looking at either the 16147060 PCM (used on the BBC/4L80E trucks, also kinda hard to find), or most likely the 16197427 that was available in a bunch of applications, and is a well documented ECM along with the codes it is capable of running. I don't recall off hand if the '7427 or it's variants were ever used in a big block application. Regardless of what you start with, it WILL require tuning to get running well. That being said I can't see any reason why the engine could not be started on a stock tune that is close to your application.

Quote:

---

Originally Posted by Aprules2

Hey everyone, I am a mechanic with prior experience working on fuel injected cars but have never built my own system. I have a 75 Cadillac Coupe DeVille with a 500 and a TH-375 transmission. I drive the car everyday and the carb is tired and and now I'm only getting about 10mpg. Rather than rebuild the carb I'd like to up grade to a TBI set up. A while back I bought a first gen analog Holley Pro-Jection set up but it didn't have the O2 sensor set up. The module for the original projection to accept an O2 is no longer available. So everyone has told me it pretty much worthless. However the Throttle body is good for 700 CFM and is a 4 barrel. It has one TBI injector per bore. It seems the GM TBI swaps are very popular however the 454 throttle body is kind of rare and very over priced. I wanted to know if I could use the Pro-Jection 4 Barrel throttle body and tie the 2 left injectors together and the 2 right injectors together and have the GM computer drive them ad if it was the 2 barrel 454 throttle body? Or would the added load cook the transistors that drive them? I like the idea of the 4 barrel because its free, plus it should yield better performance over a 2 barrel. Smaller bores so more velocity and all, plus more CFM. If not what can I do?

---

i have a couple of the holley projection 4di computers and 1 wire harness which have the o2 sensor control that i removed from a truck. if you can pay shipping you can have them if you want them.

Quote:

---

Originally Posted by bonnieclyde100

i have a couple of the holley projection 4di computers and 1 wire harness which have the o2 sensor control that i removed from a truck. if you can pay shipping you can have them if you want them.

---

Sure do they work? What would shipping be out to Paramus NJ 07652

i know works at least it did when i took it off my truck .and im sure the other does . what shipper would you want me to use let me know and i will find out.

Quote:

---

Originally Posted by Aprules2

Sure do they work? What would shipping be out to Paramus NJ 07652

---

here is a pic of them. the box will weigh about 12lbs and my state and zip is alabama 35750. you can check prices and let me know.Attachment 6630

Looks like it would fit a Large USPS flat rate box at $15.xx

Sounds great to me. Thank you. Can I paypal you? I should be able to splice my TBI into the newer digital harness right?

i would think so. they may even be the same hookup. i have paypal but i have never received money i will have to find out how to do it Attachment 6632

Quote:

---

Originally Posted by Aprules2

Sounds great to me. Thank you. Can I paypal you? I should be able to splice my TBI into the newer digital harness right?

---

looks like i would have to open a business account and they charge fees to receive money. if you use ups (maybe fedex and mail)you can set it up online and email me the label i can print it out and tape to the box. the weight is 12lbs and box demensions are 12 inch by 12inch by 8 1/2 inches.

That Holley projection will be fun to experiment with and such, but in my opinion, you should really try to go with a GM ECM and control setup. Maybe not right away, but before you get too deep in the Holley stuff. Reason being is the support. If something happens with the aftermarket electronics and you're away from home, it could be a huge problem. Either waiting for an order to be over night shipped to you, or finding out that Holley no longer makes what you need and needing to figure out something while on the road.

I use the 7060ECM in my truck, auto parts houses usually stock them, but if I was going from scratch I'd go with the 7427. They have awesome support and ability to go with port style fuel injection easily. Then maybe something like this with the bungs drilled for EFI?
Attachment 6635