67 up Dart Heater Mounting Gasket

[Dana67Dart]

So I'm making a plate to cover the AC hole in the firewall to mount a heat only box. I have all the holes and mounting points located BUT there are 4 small holes that I have no idea what they are for?
The holes are not evenly spaced around the center circle like the mounting holes are AND they are not equally spaced from each other?

Thoughts?


This is the heat only firewall as seen from the engine compartment

From DMT's website

Metal mounting ring (front)

Metal mounting ring (back) with OEM seal

T

 

[RAT ROD AL]

Dana, I have removed many of the round plate's and nothing was ever in those on ones I removed.

 

[RAT ROD AL]

Should be a black rubber donut gasket that goes on the motor before the plate goes on.

 

[RAT ROD AL]

 

[Dana67Dart]

Yep, my experience also.

But why punch holes in the gasket AND the firewall for no reason.

So odd!

 

[Map63Vette]

Weird idea, but maybe they were used to hold the gasket in place while assembling at some point? Easy enough to just use some glue or start the bolts though, so maybe not. Only other guess would be tooling or alignment holes or just something left in the design. Like they were going to use a different heater box and changed their minds last minute and just didn't want to revise the old holes out because they were already in some stamp die or something like that.

 

[Dana67Dart]

Weird idea, but maybe they were used to hold the gasket in place while assembling at some point? Easy enough to just use some glue or start the bolts though, so maybe not.

I thought that too but the studs on the firewall are welded in so the gasket hangs on the studs.

The fact that yay are not symmetrical and uniformly spaced is soo odd.

I thought maybe an air escape when the system is bolted together, a lot of gasket surface

 

[Cuda Al]

Probably for the heater delete cover plate, it would just use sheet metal screws and not the bolts


Alan

 

[Dana67Dart]

Probably for the heater delete cover plate, it would just use sheet metal screws and not the bolts

Alan for the win!

Delete Panels

Good to know and it means I can remove the holes from my conversion plate.

 

[Cuda Al]

Picture from the internet, that is why two sets of holes in the gasket. I suspect it was on the car before paint and the screws should have been painted.

Alan

 

[Cuda Al]

FYI, the clipped off side was put there as clearance on some other car, not necessary on the 67 A-Body.


Alan

 

[Dana67Dart]

Probably for the heater delete cover plate, it would just use sheet metal screws and not the bolts

Alan, do you know if the plate is flat ? it kind of looks like it has a big raised dimple in the center.

 

[Cuda Al]

Alan, do you know if the plate is flat ? it kind of looks like it has a big raised dimple in the center.

I suspect flat, I had a hard time finding a clear picture that wasn't painted black.
The LO23/BO29 crowd would probably know best (although you could have a heater delete on any car)


Alan

 

[Cuda Al]

Keep in mind that the LO23/BO29 may not have used the same cover, the valve cover is tight there and a bulge may have interfered.


Alan