Hi folks, my son just bought a 86 F150 with a 300. He’s starting in his career in HVAC and just needed something simple to drive. Body is rock solid.

Someone crafted an adapter plate to accept a Holley 2 barrel carb. They drove it this way for a while apparently but the truck doesn’t run well with it as I believe it’s too much carb for the motor. Any thoughts? I can’t seem to find the correct spacer plate to buy an original 1bbl carb. I think this truck had the electronic feedback system originally. Should I buy the carb with that system or will another pre-86 1bbl work?

Also, there is a threaded hole in the exhaust where I assume an O2 sensor was mounted. I want to plug this off with a plug. Does anyone know the correct size?

 

After doing some research (and admittingly I have not looked at the truck that close) I believe we will need to convert to Duraspark II. Couple of follow up questions:

1. Where does one find a wiring harness? Junkyards are becoming increasingly hard to find, and we are on a pretty tight budget. I would like to fine a used harness from an 80-83 truck, but is our only option a new one?
2. I understand the harness plugs to the ignition module we will have to buy, as well as a vacuum advance distributor, oil pressure and temp sensors. Where does the harness plug into the truck? On the firewall? Does this completely bypass the 86 year ECM?
3. I assume once the module is installed, the harness plugged in, etc., we set timing at idle to around 10 BTDC. What should full advance be on the I6 300?

Thanks for your help. I've had several older Ford trucks, but this is the first time having to do this conversion (I am somewhat familiar with the Duraspark ignition system).

 

There is more information in the 80 to 86 truck area above and will get more replies there too.
Yes that 86 truck with a 300 did have the feed back system.
If any 1 or more parts and not working or hooked up the system go into "limp mode" and makes the carb (feed back) rich and locks the timing (feed back).
So with this other carb & adapter the system has locked the timing and why it may not run good?
Dose the dist. have a vacuum hose or can on the side of it?
If not it is locked.

Now because of lack of used parts, you can use car parts too, most hit Ebay and buy a HEI dist. that will drop in.
All you have to do is run 12 volts to it and a vacuum hose from non-feed back carb and you are done.
They say you can find the 12 volt wire on the inner fender in 1 of the plugs from the factory harness.

As for the carb you can try what you have with the non-feed back dist (HEI?) and see how it runs or find a 80 - 82 that are non-feed back.
Now you say there is an adapter. I take it the EGR plate was removed and this put in its place?
If so then you will need to find a spacer or EGR to take up the space between the intake manifold and carb other wise the throttle linkage dose not clear.
It can even be made from wood and should be easy to make. 2 holes for the studs and 1 for the carb gases to reach the intake.
The wood will also insulate it from heat from the intake manifold.

I take it the motor still has the factory exh manifold too?
A up grade is to get 300 EFI exh manifolds and factory Y pipe as they flow better than the log manifold the truck has.
I run 1994 exh manifolds, Y pipe and pipes, less cat, all the way to the rear with tail pipe.
This way if I need any exh parts I can hit any parts store for it.

I am still running the factory 1v Carter carb and log intake manifold on my 81 F100 with a 300 six and love it.
Mine was non-feed back from the factory to start.

If you can post a picture or 2 of the carb and dist. so we know just what you got would help us help you a little more.
Dave ----

Oh The carb you can also get from Ebay as some have had good luck with them.

 

I dont know why you would need a oil & temp sender?
The temp sender out by the stat housing is for the feed back system and can be unplugged and left in the system to seal it.

As for the oil I have not heard of a sender to the feed back system for it?
EFI yes not feed back.

Once you have the non-feed back carb & dist. (HEI?) in place and running then you can remove the feed back computer.
It should be inside on the firewall up near the throttle pedal.
Working from there out into the engine bay you can start removing the harness.
Everything but think 2 or 3 wire that need to be cut should just un-plug.
The feed back system was a add on and why it can be removed and not touch anything else.
Dave ----

 

So it’s really that easy? Just get the HEI dizzy, 12v switched to it with vacuum? No need for an ignition module as I assume it’s part of the distributor? And the oil pressure and temp is separate from the wiring in the ECM system? If that’s all the case we may stick with the Holley 2 bbl for now and plug the O2 sensor hole (any idea what size plug I need for that?) and just go with HEI.

 

Also, I've read elsewhere that I will need to wire in a relay, but I think that's only when I'm having to power with a resistance wire, correct?

 

Yes only with the resistance wire.
I see over in the 80 - 86 area DaveF posted what wire color to the coil to use to power the HEI dist.

I also posted pictures of the factory intake / EGR used as a spacer and carbso you can see how it was all done.
Dave ----

 

Thanks so much!