Wiring harness choices

68RRDan · Friday at 8:00 PM

Hello all,
I tried searching for this but didn't find what I'm looking for. I am completely rebuilding my 68 Roadrunner to participate in the different celebrations for the centennial of route 66 happening in 2026.
I am currently in the process of installing a Tremec 6 speed and I'm installing EFI and A/C and a Dakota digital gauges in additional to other upgrades to make my car a very capable driver.
My question is what is a complete wiring harness that you have all used that you like that would enable all the upgrades that I'm doing. There are a lot of options out there and I'm just looking for opinions on what everyone has used and pluses and minuses to your choices.
Thank you all !!!

BeepBeepRR · Friday at 8:34 PM

PLug and play stuff is usually OE stuff. And the easiest to install. Aftermarket harnesses have a lot of work that needs to be done to them. Sure they have extra circuits for AC and stuff like that. But trying to retrofit and use factory gauges and lighting etc etc its a pain in the butt. More time making connections to old sockets and plugs. The time is better spent elsewhere. Holley Sniper 2 has a pretty cool little panel that you can get for making connections under the hood like Electric fans, Sniper, Hyper spark and whatever else you want to add. In my opinion OE is perfectly fine and less time consuming and then add what you want to it.

Runner 68 · Friday at 8:35 PM

I went with a Painless 21 circuit on my resent 68 RR build. PN 10127. Customizable. Pretty simple and straight forward if you know how to read and have a basic understanding of 12V DC power.
Having my original harness and wiring diagram available made it handy to sort out. The quality of the wire is superior. You can take a torch to it and it only gets black. No melt, no catching on fire. Plus it eliminates the fire prone bulk head connector. Does not look stock if that's your goal. I suppose you could incorporate one though. Much cleaner IMO.

Painless Performance 10127 Painless Performance 21-Circuit Mopar Color-Coded Universal Wiring Harnesses | Summit Racing

451Mopar · Saturday at 8:34 AM

Questions:
Battery Location? Stock or trunk? If trunk, does it need external kill switch per NHRA?
Which EFI?
Ignition System?
Have A/C?
Electric Cooling Fans?
Alternator type, output and regulator type?
Alternator pulley ratio and max engine RPM if known?
Head light type, or need headlight relays?
Stock dash switches and lights or custom?
Which Dakota Digital cluster
Audio system?
Alarm system?
Power windows or seats?
Other accessories?
Have original wiring harness (mainly to re-use the plastic connector bodies)?

The manual trans NSS, and reverse lights are easy to wire.

For the rear harness (tail lights, reverse lights, license plate light, fuel level sender), I would just buy the pre-made M&H rear harness.
Wires I also run along the drivers side with harness connector at front door piler:
You will need to run extra wires to the rear for the EFI pump (I use the same hole/grommet as the sender unit.)
If you have a rear amp/sub, need power wire for it.
trunk light power.
power for remote trunk latch.

I try to put speaker wires / non power type wires along the passenger side of the car.

Other harness connectors near the drivers door pilar:
Console lights.
Aftermarket console accessory power.
Door light.
Power windows.
power seats.
Likely something I'm forgetting?

Anyhow, that is what I'm thinking from the dash to the back of the car if stock battery location.

Trunk battery location will add more wiring.

radical rob · Saturday at 9:12 AM

I used haywire. The owner Denny is great to work with and as such if you need any extras added to your kit he can easily make the changes

Runner 68 · Sunday at 10:05 PM

451Mopar said:
Questions:
Battery Location? Stock or trunk? If trunk, does it need external kill switch per NHRA?
Which EFI?
Ignition System?
Have A/C?
Electric Cooling Fans?
Alternator type, output and regulator type?
Alternator pulley ratio and max engine RPM if known?
Head light type, or need headlight relays?
Stock dash switches and lights or custom?
Which Dakota Digital cluster
Audio system?
Alarm system?
Power windows or seats?
Other accessories?
Have original wiring harness (mainly to re-use the plastic connector bodies)?

The manual trans NSS, and reverse lights are easy to wire.

For the rear harness (tail lights, reverse lights, license plate light, fuel level sender), I would just buy the pre-made M&H rear harness.
Wires I also run along the drivers side with harness connector at front door piler:
You will need to run extra wires to the rear for the EFI pump (I use the same hole/grommet as the sender unit.)
If you have a rear amp/sub, need power wire for it.
trunk light power.
power for remote trunk latch.

I try to put speaker wires / non power type wires along the passenger side of the car.

Other harness connectors near the drivers door pilar:
Console lights.
Aftermarket console accessory power.
Door light.
Power windows.
power seats.
Likely something I'm forgetting?

Anyhow, that is what I'm thinking from the dash to the back of the car if stock battery location.

Trunk battery location will add more wiring.

I assume you were asking me? Or the OP?

Battery Location? Stock or trunk? Trunk. If trunk, does it need external kill switch per NHRA? Not unless you're taking it to the strip. I don't have one. This car will never see the track. But I did wire a negative disconnect lock box for security reasons. Trunk mount really cleans up the engine bay.
Which EFI? None, carbureted.
Ignition System? Pertronix Ignitor III with Ignitor III coil.
Have A/C? No
Electric Cooling Fans? Yes, dual 16" SPALs.
Alternator type, output and regulator type? 165 amp Power Master alternator with internal regulator. (Chrome )
Alternator pulley ratio and max engine RPM if known? No idea on pulley ratio, my 500" stroker taps out at 5,800 rpm. Rev limiter set to 6,100 rpm. 620 HP / 700 pounds of torque at peak rpm.
Head light type, or need headlight relays? LED with built in relays in the bulb.
Stock dash switches and lights or custom? Stock dash switches. LED lights throughout the car.
Which Dakota Digital cluster VHX-68D-STD-K-B plus the PAC-2800BT fan controller.
Audio system? Memphis Audio Headless Bluetooth unit mounted in trunk with Pioneer 8" sub woofer, Pioneer 6x9s in package tray, Retro Sound D412 in the dash. The stock thumbwheel is in the dash but doesn't have any speakers wired to it. Turns on and is lit but is essentially a dummy.
Alarm system? Kimber 1911 .45 Auto
Power windows or seats? No
Other accessories? Electric trunk popper, electric in tank fuel pump, electric cut outs, Hurst roll control, built in Schumacher 5 amp trickle charger/maintainer.
Have original wiring harness (mainly to re-use the plastic connector bodies)? Yes I robbed allot of the connectors from it and to study the routing of the various circuits. Came in real handy.

451Mopar · Monday at 12:04 AM

Questions were for the Original Poster, but really nice car Runner 68.
The Alternator and pulley ratio question is to check if running underdrive (small crank) pulley that could hurt low rpm output from the alternator, and on the other side, you need to make sure not to over rev the alternator at high RPM. The 500" stroker (499" 4.15 stroked 4.375" 400 block) in the Charger I have the redline set at 7,000. At a 2:1 pulley ratio, the alternator can hit 14,000 RPM.
Dual 16" cooling fans is impressive to fit to the radiator size.
Does the alternator output just tie into the battery supply cable? or would the disconnect kill the engine if it was running?
I did the Ron Francsis wiring kit in Mikes '69 Coronet. It was good. The select a circuit is a nice option. Still had to buy extra wire, and other stuff. Mikes car was pretty custom, EFI, TCI 6X transmission, custom dash with aftermarket switches, Speed Hut gauges, Digi-Lights Tail lights, and such. Wired the car to retain the factory bulkhead connector, but all the normal heavy loads were setup to just trigger relays so the bulkhead connectors don't have any heavy loads going through the connectors.

I have changed the wiring on my Convertible a couple times now. Trying to keep it clean, but not hidden. The FAST universal EFI harness dosen't fit and look that great, and I want to put some firewall harness connectors it the harness so I can just unscrew the EFI harness from the firewall if I need to pull the engine (not disconnect all the Injectors, sensors, ignition, and such.)

Runner 68 · Monday at 7:00 PM

451Mopar said:
Questions were for the Original Poster, but really nice car Runner 68.
The Alternator and pulley ratio question is to check if running underdrive (small crank) pulley that could hurt low rpm output from the alternator, and on the other side, you need to make sure not to over rev the alternator at high RPM. The 500" stroker (499" 4.15 stroked 4.375" 400 block) in the Charger I have the redline set at 7,000. At a 2:1 pulley ratio, the alternator can hit 14,000 RPM.
Dual 16" cooling fans is impressive to fit to the radiator size.
Does the alternator output just tie into the battery supply cable? or would the disconnect kill the engine if it was running?
I did the Ron Francsis wiring kit in Mikes '69 Coronet. It was good. The select a circuit is a nice option. Still had to buy extra wire, and other stuff. Mikes car was pretty custom, EFI, TCI 6X transmission, custom dash with aftermarket switches, Speed Hut gauges, Digi-Lights Tail lights, and such. Wired the car to retain the factory bulkhead connector, but all the normal heavy loads were setup to just trigger relays so the bulkhead connectors don't have any heavy loads going through the connectors.

I have changed the wiring on my Convertible a couple times now. Trying to keep it clean, but not hidden. The FAST universal EFI harness dosen't fit and look that great, and I want to put some firewall harness connectors it the harness so I can just unscrew the EFI harness from the firewall if I need to pull the engine (not disconnect all the Injectors, sensors, ignition, and such.)

The alternator is a one wire unit. The negative disconnect can't be touched while driving. It's in the trunk. The shiny box to the right with the key in it in the pic above.
I have a ton of wire left over from the Painless kit. Re-purposed much of it to the additional accessories, still have plenty left over. Great quality wire.

451Mopar · Tuesday at 1:00 AM

For most builds that are mostly stock, usually I recommend the factory restoration harnesses like the M&H ones from year one. Mostly as a time saver, but they have the factory colors, connectors, and such. Mikes custom wiring likely took 20+ hours. I was using my old the MSD crimpers and often had to change the dies from the packard type to the insulated terminal type which slowed me down, so I ended up buying a second set of crimpers so I would have one crimper for each of the terminal types. The Ron Francis fuse block has the screw type terminal connectors for insulated spade connectors. The fuse block is not factory connected like the painless setup.

Runner 68 · Tuesday at 9:08 PM

BTW what happened to the OP?

dadsbee · Tuesday at 9:12 PM

Runner 68 said:
BTW what happened to the OP?

Easter Bunny kidnapped him...

Wiring harness choices

68RRDan

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BeepBeepRR

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Runner 68

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451Mopar

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radical rob

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Runner 68

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451Mopar

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Runner 68

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451Mopar

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dadsbee

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