Topic: firewall heater bolt holes

[Ashley]

If removing factory air and installing heater assembly only,is there original bolt holes in firewall to mount heater housing and holes for heater hoses? Couldn't tell sure looking at bossbill firewall post

[Bossbill]

I have to update that pic and will do so in a minute.

There is an oblong slot to the right (from engine side view) of where the heater blower motor goes that you need to fill in with metal.
The outer 4 holes around the blower motor are used to mount the heater at the firewall. In the interior another bolt goes from a heater case metal tab straight up to a captive nut on the cowl. NPD has that special nut.
There are 2 small holes to the inside of the top larger heater holes of which two can be used for big block (and some Shelby) blower motor shield. I don't know about the two small holes om the bottom. See updated pic.

[J_Speegle]

Here are a few pictures of what your aiming for in the finished project as far as holes, punch trough's and dimples. Because of this some holes on an AC will need to be filled but then dimpled/punch to replicate the original form. You should also see small holes near the heater mounting holes Bill mentioned that may go unused depending on car options

Hope these help

This first one is a 6 cylinder so you may notice a couple fo holes that stand out when you see them






Those holes used for 6 cylinder throttle linkage are still found on V8's just not used but shaped differently from non-use



On this San Jose example they are shown sealed with chalking/dum-dum

[Ashley]

Thanks Jeff and bossbill, appears like heater blower motor assembly might fit in AC firewall holes as well as heater hose holes. Will have to weld in oblong patch for AC hose slot.

[mtinkham]

In the first picture in Reply #2, there are two small holes between and slightly below the two lower heater motor mounting holes (edit: one of the holes is visible, the other is obscured by sealer). What are these holes for - AC plate?

[J_Speegle]

In the first picture in Reply #2, there are two small holes between and slightly below the two lower heater motor mounting holes (edit: one of the holes is visible, the other is obscured by sealer). What are these holes for - AC plate?

The one at the upper left (looking rearward) next to the heater attachment hole was used for cars that had a heater motor shield. The one at the lower right was not  as the shield  didn't reach that far down once installed. There were two additional ones to the right and the upper right. The other goes unused. Possibly just something the engineers put in for some unknown reason or for something that didn't take place.

[mtinkham]

Thank you. I suspected these holes were not used, but confirmation is key.

[J_Speegle]

Most of the time, these would have been sealed when the firewall sealant was applied to the firewall penetration and attachment holes