'40 firewall, what's that big hole for?

[white64]

It seems that most '40 firewalls have a plug for the big hole in the center of the firewall, is that what I'm missing? Neither of the '40s I've had (such as they were) had anything there.. My '38 Plymouth (first pic) had the coil stuffed in a hole in a very similar location...

 

[PeterC]

It seems that most '40 firewalls have a plug for the big hole in the center on the firewall, is that what I'm missing? /QUOTE]
39's have that as well - I believe that was used for dealer added hot air heat supply to interior. I am not positive if correct so others will chime in and add to this.

 

[RalphM]

Heater option.

 

[white64]

Thanks! Where might I find a plug? I could make one but it looks like there is more to the plug than a round disc. Tapered edges, and I would assume bolts welded to the back of it?

 

[Kube]

Thanks! Where might I find a plug? I could make one but it looks like there is more to the plug than a round disc. Tapered edges, and I would assume bolts welded to the back of it?

It wasn't a plug exactly. It was a knock out. That is, the instrument panel was semi perforated at that area in anticipation of a hot air heater being installed.

To "replace" this, I'd suggest making a round blank to fit and welding from the rear. Or, as long as authenticity does not matter to you, how about flattening out that area of the panel, welding in a patch and finishing it smooth?

 

[white64]

That's probably why I don't have a "plug" .. the '40 sedan that was more complete had the hot air option or what was left of it in the trunk (the carbon monoxide option, might be a better description...) , never tried to figure it out. Any one need a box of hot air parts for the cost of shipping?

I'll make a disc to fit.. any welding at this point will raise hell with my checker board!

Thanks again,

 

[JSeery]

Epoxy a piece in place with a backer from the inside and paint it to match.

 

[Kube]

That's probably why I don't have a "plug" .. the '40 sedan that was more complete had the hot air option or what was left of it in the trunk (the carbon monoxide option, might be a better description...) , never tried to figure it out. Any one need a box of hot air parts for the cost of shipping?

I'll make a disc to fit.. any welding at this point will raise hell with my checker board!

Thanks again,

Make a disc a bit larger in diameter than the hole. Weld a stud to the center (back side) of the disc.
To hold in place, drill a hole in a piece of (example) 1" x 1/8" x 4" steel. Place that over the stud (beneath the dash) and mock washer and nut. Walla! No fuss, no muss and noooo welding.

 

[white64]

Got it, took a 2.5 inch hole saw, 1/16 plate, voila! A plug! With a centered hole! just use the two side holes (where there was a clamp for the heat tube, I guess) to support a crossbar inside, the "plug" outside, a stainless machine screw! and done!