C2 heater box seal - where does it fit?

[Timothy B.]

The heat box kit I ordered is complete but included no instructions at all. All of the seals are self explanatory except for the large C shaped lighter grey piece that is made out of a softer foam material. Upon disassembly, I didn't find anything that looked like this seal. In the assembly manual, it appears to show a C shaped seal glued in place to the lip of the heater box AFTER the box is installed. It doesn't show it between any parts of the box and the firewall.

Can someone please describe precisely where this seal fits and what its purpose is, since the two harder black rubber seals appear to do the necessary sealing.

[Harry Sadlock]

Re: C2 heater box seal - where does it fit?

Tim, if you have the Dr. Rebuild catalog, page 44. The large lighter gray "C" shaped seal is called the Inner Box Seal Mounts With Core. There is a picture.

I rebuilt my 63 last year. After I had the new core in place in the inner heater box this was the next piece I installed. If you do not have the catalog, send me your email address and I'll scan you the page.

Harry

38513

[Timothy B.]

Re: C2 heater box seal - where does it fit?

Well, I understand what you are describing Harry and I do have access to Dr. Rebuild on his website and I have reviewed it, but those diagrams don't seem correct to me. If I look very closely at the assembly manual it appears that the lighter grey "insulator" is attached to the flange of the heater box from the INSIDE of the car, and not between the flange and the firewall. Also, the insulator that came in my kit is die cut in such a way that that it doesn't seem to fit in-between the box and the firewall. Dr. Rebuild shows the insulator with holes in it for the studs of the heater box, but there are no holes in the insulator - I would have to punch holes. There is a "lip" made into the insulator that would be facing the wrong way also. The grey seal has a unique shape to it that doesn't seem to fit anywhere except on the other side of the heater box flange.

From what I can tell, the order of parts appears (not yet confirmed) to be to be something like this, starting from the outside:

>>Blower box/

>>Black rubber seal with die cut holes for studs and pipes/

>>firewall/

>>black rubber seal with die cut holes for studs and pipes/

>>core mounting plate (with core attached)/

>>non-hardening sealer (as called out in service manual)/

>>heater box assembly/

>>C-shaped grey seal, glued in place to flange of box.

When I removed my heater box, which I don't think has ever been removed from the car and still had the original 1966 dated Harrison core in it, there was no evidence of a foam seal at all located in-between the box and the firewall. The only thing there was the black harder seal that was firmly stuck in place, and remainder of a pliable caulk-like seal material that I assume was the "non-hardening" stuff. I didn't see anything like the grey foam anywhere.

Just putting my "engineering" hat on and looking at the design, it doesn't seem to me that the grey foam seal would have anything to do with the sealing of the box to the firewall. This theory is also supported by the fact that GM called it an "insulator", and not a "seal". The black rubber part was the seal. I think it's purpose was to "insulate" the area right around the heater box to firewall joint to help prevent drafts from heat leaks past the seal.

I wish I had taken photos, but I have fitted the box back in the car as described above and it fits fine. Since the way it seems to want to go together just from looking at the parts is different then some of the diagrams I have seen in catalogs I figured I would discuss it with the forum before finalizing the installation. The bottom line is this: Does the lighter grey seal lip get trapped in-between the heater box and firewall during installation or does it get glued in place on the inside of the flange of the box AFTER the box is in place?

[Timothy B.]

Re: C2 heater box seal - where does it fit?

Here is a diagram from the Corvette America website that shows the parts. I think this diagram might actually be from the assembly manual.

[Harry Sadlock]

Re: C2 heater box seal - where does it fit?

Tim, my 63 AIM calls out the foam as an Insulator also. When I was putting mine back together I spoke with the folks at Dr. Rebuilds several times. They were very helpful. What I learned was that depending on the year 63 to 67 the installation was different, also, it depended on who was installing the box. Therefore, Dr. Rebuild providers in his kit all the parts that could be used, but suggests to use only the parts that you actually removed from your car.

As long as it doesn't leak water and it keeps engine compartment heat out, you probably have a good fit.

Harry

[Richard L.]

Re: C2 heater box seal - where does it fit?

Tim,

Before you button everything up, you might want to do a low pressure air test on the new heater core, just to give you peace of mind...The new heater cores leave a lot to be desired from a QA/QC standpoint...

Don't ask how I know this...

Rick