Thread: Location of wiring harness firewall exit holes

Tweet

I mounted my fuse panel on my 32 5-window in the upper left corner of the firewall. I haven't found any photos showing a good location for the harness to exit to the engine and to the headlight and radiator area. Should I locate this low in the foot area? Any photos or suggestions will surely help.

I used the billet cover for the grommet, and just went through near the steering column - Billet Wire Port Didn't recall the $42 price tag, but might have been......

DSC01079.JPG

For my headlight wires I punched holes through the body/frame in the toeboard area, and ran them inside the rails, since they were coming out in headlight conduits.

Originally Posted by rspears

I used the billet cover for the grommet, and just went through near the steering column - Billet Wire Port Didn't recall the $42 price tag, but might have been......

Roger, I know if your like me you always find out later but Parr has em' available for $29.95 from Parr Automotive.
I know it might be extreme but on my latest ride down by my left foot I drilled the floor and on thru the frame which is boxed and made a plastic bushing (to keep from chaffing) so all the wiring could be ran inside the boxed frame rails, both on the passenger and drivers side then I fabb'd a similar billet wire port and fastened it to the frame to have the wires exit the frame at the front and in the engine compartment, there are reasons not to do it that way but it sure made it easy and sanitary looking. On my other ride I used one of the Parr billet ports above my distributor to run in & out the engine wiring and ran the rest out by the passenger footwell through a grommett. Best of luck Matthyj

So the frame rail routing is what is keeping the firewalls so clean and free from wiring clutter. Thanks for the suggestions. Anyone else have wire routing advice? This is one part of the build where I have no previous experience. I have replaced and repaired factory harnesses, but this is a first time experience.

On my Car I ignored the first rule of Car Building-keep it simple stupid (KISS)! I have a lot of electronics (Power Door locks, Power Windows, remote Door Locks, EFI, redundant Sensors (Fuel press., Oil (2), Coolant (2), Trans Temp, etc.), GPS Speedo, more-

I had (have) the same problem you are experiencing, and I chose to route my Wires through the toe board as well-with all of my EFI harnesses and such, I couldn't put them through a port (waaay too many), so I took some Belting and aluminum sheet and made a "port" to fit the toeboard outline and used the belting to seal the Harnesses (hope that makes sense) and, I used nutserts to hold it down-

It completely seals my Floor (and, being the Aluminum is polished,
it looks reasonably well)-hope this helps (if you have a lot of Wiring like me)-

Thanks for the reply. I don't have the power accessories, but do have the EFI setup. I'm concerned with ECU location and harness routing. I think I can route much of the conventional wiring through the frame rails as suggested and be ok there. I had planned to mount the ECU up high under the dash, but am concerned with dirty/noisy interference from other components. I need to research this part of the wiring further before I start mounting stuff. Any suggestions on this would be appreciated.

Originally Posted by Deuce4dad

Thanks for the reply. I don't have the power accessories, but do have the EFI setup. I'm concerned with ECU location and harness routing. I think I can route much of the conventional wiring through the frame rails as suggested and be ok there. I had planned to mount the ECU up high under the dash, but am concerned with dirty/noisy interference from other components. I need to research this part of the wiring further before I start mounting stuff. Any suggestions on this would be appreciated.

My ECU is mounted high, centered under the dash with the harness penetrating below, aligned with the top back of the engine. The only thing they say is to keep it away from an MSD unit, and the main power feed conductor from the battery to the MSD. I'm not running an MSD so no worries.

Originally Posted by Deuce4dad

Thanks for the reply. I don't have the power accessories, but do have the EFI setup. I'm concerned with ECU location and harness routing. I think I can route much of the conventional wiring through the frame rails as suggested and be ok there. I had planned to mount the ECU up high under the dash, but am concerned with dirty/noisy interference from other components. I need to research this part of the wiring further before I start mounting stuff. Any suggestions on this would be appreciated.

I mounted my ECU under the left side of the Dash, and my Fuse Box is on the right side kick panel to isolate them a much as possible-as for RFI, I made certain that my trigger wires didn't run next to constant hots, or, I ran them at 90 degrees to each other if I couldn't-

On my ECU you are supposed to run the main power & ground (in my case I ran 8 AWG) directly to the Battery Posts (they use the Battery as a capacitor), and I ran them down the Trans Tunnel (with Ron Francis "Gray stuff"-I used this on the Driver's side also, to run my trigger wires for my Fuel Pump,, etc.)-

I too, was very concerned about interference, so anywhere that I thought there might be a problem, I used this:
https://www.zippertubing.com/EMI-Shi...ps/Z-Foil.html

hope this helps-

On my new car I fastened the fuse panel to a piece of plate steel with another 1/4" piece of plate aluminum with a 3" hole in it on the back of the steel both being as wide as my fuse panel and as long, then under my dash I went to Westlake Hardware and purchased a very strong 3" round magent and fastened it to the firewall, that way my fuse panel snaps onto the magnet and locates itself because the magnet sticks in the center to the steel and not to the aluminum (as well) I left the harness long by about 8" so I can grab the whole panel and yank it down to see what is going on as its up high behind the dash. This was a low cost variation of Ron Francis's system but works well for me and cost just a few bucks. Best of Luck

Originally Posted by Matthyj

On my new car I fastened the fuse panel to a piece of plate steel with another 1/4" piece of plate aluminum with a 3" hole in it on the back of the steel both being as wide as my fuse panel and as long, then under my dash I went to Westlake Hardware and purchased a very strong 3" round magent and fastened it to the firewall, that way my fuse panel snaps onto the magnet and locates itself because the magnet sticks in the center to the steel and not to the aluminum

That is brilliant!!!!

Originally Posted by 36 sedan

That is brilliant!!!!

It really is brilliant, more so because I'm one of the idiots that bought that Ron Francis Harness (for too much money!)-

I had no room under my dash for my ECU. It's got 3 big plugs and about 80 wires running to it. The only picture that I took was during mock up. It's mounted on the trans tunnel, a little further up than in the picture. I bonded a board to the tunnel and attached the ECU with 4 screws and some small rubber vibration isolators. About 20 plugs have to be fed through the firewall, so I have a 1-1/2 inch hole for each side of the engine, aligned with the valley , at the base of each cylinder head.

The fuse box shown is only for the engine and trans. There's another in the trunk for all other wiring. I routed wiring to the headlights through a very low spot, below the foot well, but if I got inside the frame, I'll have to drill a hole to do that. My taillight wiring and all other wiring from the trunk mounted fuse box run along the drive shaft tunnel, inside a console.

'37 Oze build

Thanks so much for taking the time to reply. I really appreciate everyone's help. This forum has always provided a great wealth of information to me. Thanks again everybody.