The Ford Barn

Clrascoe · 03-26-2026, 08:32 PM

I am replacing the wiring harness on my 47 Coupe. The dash is currently out of the car. I would like to install the new harness to the dash while the dash is out of the car and on a workbench but I am concerned about getting the other half of the harness (the engine compartment wires) through the hole in the firewall because the section of the harness where the engine compartment wires split out, which will need to go through the firewall, is so thick. Does anyone have experience with this issue? Thanks

ford38v8 · 03-27-2026, 02:28 AM

It’s the same wires on one side of the firewall as the other, only split into groups on the interior side, which itself is a hassle to move through the hole. Not sure on the ‘47, but in my ‘38, I had to split the rubber grommet to get it on after the harness went through the firewall. This did turn out well, but it was the most difficult part of the job.

1942deluxe · 03-27-2026, 08:41 AM

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I did my 42 and 46 Fords with the dash in the car, but I think could be done either way. I'd do the dash wiring on the bench and install the dash. Then feed the light wiring thru the firewall. Wire for the solenoid needs to come thru also and maybe one other wire. I then installed the grommet. I can't remember if I split it as Alan mentioned but it worked well. The lighting wires are fairly short coming out of the firewall. Used a Dennis Carpenter harness on both cars and it was user friendly with good diagrams.

03-26-2026, 08:32 PM	#1
Clrascoe Junior Member Join Date: Jan 2024 Posts: 14	Installing a Wiring Harness - 47 Coupe I am replacing the wiring harness on my 47 Coupe. The dash is currently out of the car. I would like to install the new harness to the dash while the dash is out of the car and on a workbench but I am concerned about getting the other half of the harness (the engine compartment wires) through the hole in the firewall because the section of the harness where the engine compartment wires split out, which will need to go through the firewall, is so thick. Does anyone have experience with this issue? Thanks

03-27-2026, 02:28 AM	#2
ford38v8 Senior Member Join Date: Jul 2011 Location: SF Bay Area Posts: 7,634	Re: Installing a Wiring Harness - 47 Coupe It’s the same wires on one side of the firewall as the other, only split into groups on the interior side, which itself is a hassle to move through the hole. Not sure on the ‘47, but in my ‘38, I had to split the rubber grommet to get it on after the harness went through the firewall. This did turn out well, but it was the most difficult part of the job. __________________ Alan

03-27-2026, 08:41 AM	#3
1942deluxe Senior Member Join Date: Jan 2011 Location: Albion, PA Posts: 1,100	Re: Installing a Wiring Harness - 47 Coupe Sponsored Links (Register now to hide all advertisements) I did my 42 and 46 Fords with the dash in the car, but I think could be done either way. I'd do the dash wiring on the bench and install the dash. Then feed the light wiring thru the firewall. Wire for the solenoid needs to come thru also and maybe one other wire. I then installed the grommet. I can't remember if I split it as Alan mentioned but it worked well. The lighting wires are fairly short coming out of the firewall. Used a Dennis Carpenter harness on both cars and it was user friendly with good diagrams.