Topic: Firewall holes or dimples.What are they for?

[hertz350]

I have seen the 4 small holes each one being located next to the stud and nut that are on the heater motor on several cars. Why are they there and in some cases are they actual holes?

[CharlesTurner]

Probably a carryover from an earlier design, like for a Falcon?  Or maybe intended for a different type of attachment for a heater delete plate.

[jwc66k]

There are no holes on my Oct 65, San Jose GT Fastback, and none on my Oct 65, San Jose Hardtop either. There is a lot (yes, it is two words) of sprayed on sealant covering most of the area (done sloppily by assembly line workers) where the holes appear on your firewall.
One additional detail - the tape holding the two leads from the fan motor should cover the two halves of the motor housing, and not retain the wires. The one shown below went into 6S1902.
Jim

[hertz350]

Thank you for the picture and for the input, Jim. I plan on re doing the tape. The holes still baffle me unless there were there for a heater delete plate which I have never seen  in person.

[J_Speegle]

I have seen the 4 small holes each one being located next to the stud and nut that are on the heater motor on several cars. Why are they there and in some cases are they actual holes?

These are commonly found on 66 San Jose Mustangs. In some cases they appear to be incomplete - only stamping dimples while other times they appears to be nice round holes. In other cases only some are visible while if present often filled or covered with spray sealant as part of the connected spray pattern the workers typically followed like the six cylinder passenger side throttle mounting holes we discussed (through emails) last week

Depth and hole clean the holes came out may be related to different stamping machines and or dies put in the machines. Since this was a common panel used by all body types and possible Ford models they likely had multiple machines stamping out the same panel.


Here are a few examples for reflects. Only a small number of the ones I have

Just dimples in the metal



Visible only on the bottom ones and uppers appear to be filled (ignore the yellow chalk marking)






Bottom holes are visible uppers, barely visible, appear to be filled by the spray



All four visible



Filled? One upper right one is visible

[hertz350]

Thanks, Jeff. That is a nice assortment of pictures. I am ready to spray the adhesive on the firewall we will see what that does to the dimples/holes.

Regarding the tape on the heater motor, I have seen people use black gaffers tape. Is the most correct way to use regular yellowish masking tape then to spray it with black paint?

[J_Speegle]

Regarding the tape on the heater motor, I have seen people use black gaffers tape. Is the most correct way to use regular yellowish masking tape then to spray it with black paint?

Would NOT use gaffers tape since that is not what was used originally. There was no fabric in any of the original 66 examples I've seen. Believe you will find that the masking tape will serve the purpose well

[jwc66k]

Believe you will find that the masking tape will serve the purpose well

Black masking tape is carried by AMK under their stock number B-11665 ($12) for a 2 inch wide roll. You will have to cut the width to 1 inch.
Jim