Ok I have an 87 bronco ,swapped from a EFI 302 to a carb 351w. i want to remove the wire harness keeping on the things I need. Can anybody help identify the wires i need to have

 

WHY??? Do you know that its easier to keep the efi. the harness will work for a 5.8 swap.

 

I agree with KB---give a lot of thought to going FI on the 5.8.

You will have to mount an aftermarket fuel pressure regulator to regulate the fuel pressure down to the 5-7 psi for the carb. You will need a 3 port, 1 will have to be the by-pass after the 5-7 psi regulation to act as a return to the tank. 1 will be the fuel from the tank, 1 will go to the carb. You will also have to add a leed to fool the PCM into thinking it is receiving pulses from the engine running so it will pull up the relay to turn on the fuel pump. Without it, you "aint" going to get fuel. I have done that on a conversion to carb on a 302. I will have to look back to refresh my memory. I'm thinking it is the tach signal, wired to the correct term for the PCM---dont hold me to that--yet Do the 87's have the ignition module mtd to the side of the distributor?

 

The signal needed would be the PIP sensor from the distributor because that's what tells the PCM what the spark timing is. This gives the PCM enough information to calculate the necessary fuel delivery rate.

I have to agree with both these guys though... its a nightmare of a change to go backwards with technology here. And with the EFI you have the EEC-IV system that will basically TELL you what's wrong with it IF something goes wrong. Beats the heck out of hunting down the problem and spending hours and dollars replacing parts that may not be be cause of the problem.

Oh and if I can throw one more potential issue at you... EFI will keep running with the truck way off camber. Haven't met a carburetor yet that will do that safely.

 

maybe I worded this wrong. The 302 removed was an EFI, but the 351w installed was from an older bronco, late 70's is my guess. It already had a Edelbrock manifold and carb installed along with MSD ignition and distributor. It has the mechanical fuel pump installed as well. The PCM is not even on board any more. Nothing is EFI on the truck itself. I have custom gauges installed. The original wire harness from the EFI engine is still there and I want to remove it to clean things up.

 

Ah, well then most of the harness can come out. The EEC-IV sensors compound the number of wires in the harness by about two or three per sensor. You only need to get power and ground to those locations that require it. Since the EEC-IV wiring harness terminates primarily at the PCM, anything running back that way can go.

What ignition system are you using? That will determine the bulk of the wiring requirements for the engine that is in there.

 

See what I figured was the only wires I needed to run were ignition, lighting, carb (since its electric choke), gauge wires and any accessory I plan on using. Would this be correct? or am I leaving something out?

 

Nope, sounds like you've got it covered. As long as you have everything in place for the charging system everything else is just whatever you decide to add for your own convenience.

 

I love to see the old stuff being used! As you can see by my signature, I now only need one hot line to keep my beast alive. Can't believe the looks I get when people hear the diesel clack and see the black smoke in their face from a Bronco at stop lights!

 

Thanks Grey! Guess I know what I am going to do RIGHT this minute now!