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I think you are correct, yours is a early model truck and it's rare that people convert these to HEI. The ones starting in 1984 are usually the engines converted to HEI, since they had the computer control on all the 300's. If you look at this diagram of a 1985 with the computer control, you will see they just tied the red/lightgreen and the white/lightblue together. That is why using the white/lightblue works on the later models, but probably would not work on yours unless you twist those two wires together. Good catch on that.
P.S. It's nice to run into someone that can read the electrical diagrams. It's a rare occurrence lately.
Last edited by Franklin2; Feb 22, 2026 at 04:24 PM.
If you have a oil light and not a gauge when you first turn the key to run but not start all the warning lights should light up for a few seconds to show the bulbs are good.
So the oil, charge, seat belt, brake lights should all light up.
On the HEI they should have a full 12 volts to get a good spark.
As a test you can run a jumper wire from battery to the HEI "BAT" connection on the distributor and see if it starts and runs better.
If it does then figure how to get a full 12 volts to it maybe a relay triggered from the wire now powering the HEI?
Dave ----
The only thing that lights up with key on is the Alt light. Across the top the only thing I've seen work is one of the turn indicators and the 4WD light. I'm not overly concerned about that now, but coolant temp and an oil PSI light would be nice since I don't have any history with the vitals of this engine. The PO has been into the ignition switch which, while it "works", at times you don't need a key for the most part and the turn signal switch is flakey. The signals flash erratically, like a bad flasher, but I'd guess there's more to it. Again, my focus is the mechanicals as it is looking more and more that if I keep this thing, a cab swap might be in the future. I've found two trucks that would be great candidates, one is the same long bed and candy apple color, the other is a flair side (as you say) XLT that is a basket case but a nice unmolested cab. I like the latter body style better, but would have to either shorten the frame or convert the 2WD frame over to 4WD which is actually an intriguing project. I need to find that thread again to capture some of the finer details.
Well if you only have 1 light that comes on when key to run and shorting the oil wire to ground does not light a light ........ wait if you have a temp gauge I thought you would have a oil gauge also?
But thought you said something about the way the sender works that the light should come on?
Got a picture of your gauge cluster so I know what you are working with?
As for 4x2 & 4x4 trucks if they are F100 / F150 I understand the parts swap pretty easy as both use twin beams up front.
I would say as long as the roof does not have rust holes the body can be fixed as there are patch panels and floor panels.
I know because I have used them on my truck as part of the cab off frame rebuild. If anyone wants to know Tabco.com is who you want to use for the panels.
Dave ----
I am impressed I think that is the first time I seen all the lights lit on a cluster
I have one bulb that blinks just to the right of the tach area I just hate to pull the cluster out as everything else works and you know how that goes.
Wonder why they did a temp gauge and not a light?
But you are right if you ground the oil wire the light should light up but you said it does not light when the key is first turned on?
I dont know but wonder if it has to be hooked to the sender for the light to "test"?
I just checked my truck, 81 F100, and on the top row only the "fasten seat belt" lights up a long with the buzzer.
I believe there should be a "brake" light too. This is not for the parking brake but when the system looses pressure and the pedal goes to the floor.
I guess if I pull the cluster I would look into that brake light too.
I do know the high beam & turn signals work and mine is not a 4x4 so no light.
Dave ----
Well I took the new truck out to do one thing I expect to use this beast for, haul firewood. My cutting partner commented that my '65 F250 took the load a lot better, and he's right, but we made it just fine. Here's the kicker, my oldest daughter was excited because most of this load it to be split, and she loves running the splitter. I wish I shared that enthusiasm, lol. However now is the time to prepare for next year, so the work continues.
Well you are comparing an orange and a pear
You 65 is a 250 3/4 ton where this is a 150 1/2 ton so not really close.
I would also call that 65 a 1 ton the way they built them back then.
Had a 64 350 single rear wheel tow truck that was a best even with the worn out 292 v8 that you checked the gas and filled the oil it burned it so bad we had to put a stack on it so we would not die when hooking out to cars.
Did fine. It wasn't a completely full load, but pretty good nonetheless. Might be a 1/2 cord once split and stacked. That big 6 has plenty low down grunt. Truth be told the '65 is also an oil burner which is why she's going down for a much needed engine replacement (397 FE to replace the worn out 352). However the '81 has something the '65 doesn't, 4WD. There have been times, where this would be a major benefit when I'm out in the sticks. Today, not necessary at all, absolutely beautiful day and it's been very dry here.
I guess if you find it drags the bumper too much you could always add helper springs, not the type on the shocks, or air bags.
I read in the trailer / camper area most new truck need air bags to get them to haul right WTH is with that
Think that is what happens when they start making them to ride like cars and not trucks like they are
Dave ----
The only thing that lights up with key on is the Alt light. Across the top the only thing I've seen work is one of the turn indicators and the 4WD light. I'm not overly concerned about that now, but coolant temp and an oil PSI light would be nice since I don't have any history with the vitals of this engine. The PO has been into the ignition switch which, while it "works", at times you don't need a key for the most part and the turn signal switch is flakey. The signals flash erratically, like a bad flasher, but I'd guess there's more to it. Again, my focus is the mechanicals as it is looking more and more that if I keep this thing, a cab swap might be in the future. I've found two trucks that would be great candidates, one is the same long bed and candy apple color, the other is a flair side (as you say) XLT that is a basket case but a nice unmolested cab. I like the latter body style better, but would have to either shorten the frame or convert the 2WD frame over to 4WD which is actually an intriguing project. I need to find that thread again to capture some of the finer details.
If you did that cab swapping in my state, you would be basically buying a new truck and scrapping the one you have now. Makes the paperwork and titling easier. A whole cab comes with a different VIN. Can cause complications if you do not have a title with your donor cab.
If you did that cab swapping in my state, you would be basically buying a new truck and scrapping the one you have now. Makes the paperwork and titling easier. A whole cab comes with a different VIN. Can cause complications if you do not have a title with your donor cab.
And bigger problems if they look at cab VIN and frame VIN and they dont match.
This could be a problem if you dont have plates for the cab VIN and need to take it to be checked or if you ever sell the truck.
I gave a F150 frame away but I think the person already had plates for the truck.
It has been years but would think if he has a problem he would have reached out, I kept the title as I still have the cab with VIN plate.
Dave ----
Addressing a few small items today and have a broken "spring" that holds the door open on the door hinge.
Good side:
Broken side
And the offending broken spring
Are these available?
EDIT: Upon further review this appears to be a dentside type door hinge, they show this in the hinge assy dwgs, but it is not available separately, if it is the correct part.
Last edited by PROSTOCK; Mar 14, 2026 at 07:51 PM.
I want to say I think LMC has them as one or both of mine are bad / broken but been that way for six years now so I can live with it the way it is.
I also dont remember what trick it took to get it back in?
Dave ----
