Topic: 70 Dearborn Firewall Holes

[1970 Snake]

Can someone advise what the large hole is for in the firewall above the wiring harness opening, I assume the small one above the throttle cable square port is for the manual choke cable.

[J_Speegle]

The hole was not used for electrical or other things passing through on all 70 Mustangs. In the next example (an AC equipped car) it was used to pass vacuum lines through the firewall.




On these two examples (equipped each with a manual choke and no AC) the hole is not used and instead has a flat plug inserted




This picture was posted in the unrestored picture thread area of the site under  70 Dearborn CJ Convertible.......  Picture EC-5


Hope this helps

[1970 Snake]

Yes thanks perfect, I was pretty sure it was not used, but when disassembling my car I found someone previous to my 30 plus years of owning the car, had popped out the hole plug and put the choke cable through it, so I was not sure what actually went through it if anything on my car.

[J_Speegle]

Yes thanks perfect, I was pretty sure it was not used, but when disassembling my car I found someone previous to my 30 plus years of owning the car, had popped out the hole plug and put the choke cable through it, so I was not sure what actually went through it if anything on my car.

Based on other similar cars I would route the choke through the hole (smaller one to the drivers side) and put a plug back in the whole we're discussing.  The pictures should provide you with the confidence in your choice

[1970 Snake]

Yes thanks Jeff, your pictures especially the last two provide a good detail of the installation detail I was looking for. I have the small choke cable grommet installed now, ready for the choke cable and will put the right plastic plug in the larger hole as shown in your pics, thanks again.

[Mike_B_SVT]

I did a bunch of research on this a while back when I was trying to figure out what kind of grommet to use on my choke cable.  My car only has the large hole cut, so the small cone-shaped antenna grommet won't work on my choke cable.  I ended up using a large body grommet with a hole in the middle.

What I figured out was that they would cut additional holes in the firewall depending on how many were needed for various electrical and AC pass throughs.  My car only needed one hole for the choke cable, so that's all I have.  Your car must have some option that required an additional pass through for power leads or AC lines.
Mine wasn't the only example I saw with the choke cable through the large hole.  Quite few guys on the Boss forum had the same thing, and there were also quite a few with choke cables through the small hole.