Hi guys, I may have asked this before but I don't remember. I am getting close to wiring my old farm truck. This truck is bone stock other than I swapped in a 302 and c-4 because the original was gone.

Everything else is bone stock, even the old patina'd paint. I have looked around and I see that I can get an original style harness from mid fifty for a pretty reasonable price. I want to also convert it to 12 volt.

How easy is it to adapt the 302 to the original style harness? I am not adding anything else to this truck, no fancy power anything. Might swap the heater motor for a 12v and also do the 12v wiper motor but that is it. I cannot see spending 6-800 on a custom harness.

​​​​​​​What at all do I need to do to make the truck functional using the stock harness?

 

The major difference I can think of is the charging system. If you're using a modern 302 with an alternator you won't have the voltage regulator to wire, I think the alternator has an internal regulator. I would suggest using one of the easy wire wiring harness. I've never used one but many on this board have. I'm sure a few of them will come by and give you better advice than I can.

 

My setup would be pretty similar to yours, I swaped in a 429 and t56 but wiring wise kept pretty much everything stock. I used an american autowire 21 circuit wiring harness. 21 circuits was more than I needed but i have extra if i decide to go fancier later. It was well marked, the diagrams and instuctions were good, and it came with pretty much all the connectors I needed. The advantage you would get with a harness made for the truck would be that the wires are already cut to length presumably. I ran some of my wires differently than stock though, so a stock harness might not have fit like I wanted.

 

I also want to keep the original look of the truck. Those harnesses you speak of connect to all the original gauges, switches, etc?

 

Any re-power provides challenges. An OEM harness will fit up to the gauges correctly but will have a few extra circuits that you won't use. Wires will also probably be of improper length. If your alternator is rated more than the original generator then you will have to upgrade the "GEN" wire that loops through the ammeter.

 

What would somebody do if they replaced the flathead in a '53 with a 302 and wanted 12 volts? I know they would not have to totally re-wire the whole truck. It has to have been done a ton of times. I guess that is what I am asking.

 

No doubt it has been done a ton of times, but other questions remain. Was it done a ton of times correctly? What alternator is on the 302? Yes, you should change the solenoid to 12 volts as well as all the light bulbs. You will have to install a voltage regulator for the OEM instrument cluster to function correctly. Changing sending units isn't necessary unless they won't fit. You will have to reverse the direction of the wire through the ammeter inductive loop for negative ground.

 

not sure what alternator is on it, I assume the factory one. Wiring is not my specialty. I did a stock 48 F-1 a few years ago using an original style harness and it was pretty easy. Just looking for advice to wire this thing using everything original except for the engine.

 

If the stock 302 alternator is rated at more than 60 amps you will have to run a new larger (depending on the rating) wire through the ammeter loop to the circuit breaker, and from there to the solenoid. You will also have to add wiring for a voltage regulator if it's so equipped. Change the solenoid to 12 volts. You will need a voltage reducer for the instruments. Other than that you can pretty much use the old wiring if it's in good shape. Did you megger any of it to be sure?
Best to find the rating of the alternator.

 

And don't forget to change all the bulbs and the turn signal flasher if equipped.

 

there is no wiring in my truck at all. No circuit breaker, nothing. It was all ripped out by the previous guy who had it. It is all in a box and in very poor shape.

 

What year 302? Is it carbed or EFI? Later alternators have the voltage regulated through the computer. Point ignition or electronic?

 

the 302 came out of a 1971 bronco. Two barrell carb, manual choke, points.

 

Wow. Ok. So you're basically starting from scratch. Don't know the year of your truck, but depending on the year you may have two circuit breakers attached to the backside of the instrument panel. Complete OEM wiring harnesses are available from many sources like LMC and Dennis Carpenter if you want to keep the wiring as original and stock as possible, and their installation is pretty simple and straightforward. Aftermarket custom harnesses are also plentiful and desirable if you plan on adding additional circuits such as turn signals, radio, etc.

 

it does have a circuit breaker attached to the instrument panel. It has two breakers.