Topic: A/C holes thru firewall in a April 65 SJ Convertible

[Indycanard]

I'm installing an "original" A/C system to my April 65 SJ Conv. There are no dimples or a "knockout" on the metal firewall.  The original firewall pad (original to this car) has a vertical rectangular pre-punched hole on the pad.  My assumption is this rectangular part of the pad is removed, and the hole is drilled.  I have a new oblong rubber seal and retainer bracket for the hose pass thru. 

What is correct for my car? Two individual holes (if yes, what hole size?), a single oblong hole(if yes, what are the dimensions?).

Thanks,

Henry

[CharlesTurner]

If you don't have the knock-out plug, then the car would have had 2 separate holes for the A/C lines, each with a grommet.  Look on the engine bay side of where the pull-out would be on the firewall pad.  IIRC, there may be dimples there.

[Indycanard]

Well, I don't have dimples, nor do I have individual grommets. I either get two grommets, or make a cutout similar to what the knockout size is to use my oblong single grommet. Anyone have the knockout size? If I go with the individual holes, what size are they?

Thanks 

[CharlesTurner]

Why would you do the knockout when you say your car clearly did not have it.  If you don't have it and want this installation to be correct, you should have two separate holes.  The grommets used are the same as the ones used at the radiator support.  I'm sure someone can provide pics of where the holes should be.

[Indycanard]

Thanks for the sanity check Charles. I need to order the grommets for the radiator, so I'll just double the order.  I'm using (Classic Auto Air)  new A/C hoses (for 134a), so I hope they fit the grommets.  Can you tell me the hole size thru the firewall (obviously the same size I need to drill thru the radiator support)?  Where does the clutch wire pass thru the firewall?

Thanks,

Henry

[Chris]

Here's the firewall panel for a 64 1/2 mustang. This was sent with some original A/C parts I purchased recently. You can see the hole placement relative to the other cutouts and the second picture shows the hole size to be approximately 1 1/4 inches circular.
 

[CharlesTurner]

Here's the holes on a Feb '65 San Jose car: