[Terry M. Hunt]

Refinishing the attaching screws for the heater blower case and evaporator case on my 66 GTO. These are the screws that attach these two assemblies to the firewall. I have a total of 12 screws. 11 of them are identical to example A in the attached photo. There is only 1 that looks like example B. Is example B intended to go in a specific location or for some specific purpose? Or maybe it’s just a random screw that somebody used because they lost one of the screws while working on the car in the past? I forgot to note what location this odd screw came from when I removed it.

[428ho4spd]

Sorry, first post I was thinking a non-air car. Here's an original untouched example of that one screw location, near the underhood lamp shown here.

[gto4ben]

Per the 67 Assemble Manual, One screw, [3], (9780719) has a lock washer. The others, [2], (1366017) are with plated washer. Torque to 30-45 lb.-in.

[Cardo]

Screw B is to ensure that the case has a good ground for the blower motor. It is supposed to be there.

[Terry M. Hunt]

Many thanks for these responses. The pic of the firewall is very helpful. The Star washer is something I always associate with ground circuits, so learning that it is there to ground the blower motor makes sense.

I have a second question regarding the fasteners in this area. On page 261 of the Ames catalog part number P120YJ is described as “64-72 evaporator housing to firewall stud and nut”. I vaguely recall removing a stud and nut from the firewall when removing the evap case and blower case. Don’t recall exactly where it was located. Can you guys help me with that.

[Cardo]

I don't think they're used.... I have 2 factory air cars, one with 42000 miles and neither has it.

[Terry M. Hunt]

Cargo, that’s good info. I wonder if this could be one of those assembly plant differences. I’m also wondering what the purpose of a stud would even be in this area. I looked through my copy of the 67 assembly manual for info on this but didn’t turn up anything. Of course the quality of this manual is really lousy. Many pages are so faint you really can’t make out anything. Can you tell me the assembly plants for your two cars?

[Terry M. Hunt]

Cardo, apologize for goofing up your screen name. I’m sure the Chevy gods will punish me!

[Cardo]

No worries. One of my cars is Fremont, the other is Pontiac. The Fremont car is the 42000 mile car, is unrestored and not taken apart yet. The Pontiac car is restored, and is a 63000 mile car.