Too late to turn back now ... lol. Nice job taking the plunge. I dread the idea that ultimately, mine will need the same treatment. Nice touch with the cargo strap. Good thinking. Got to agree with Craig. Make it metal, weld it all in. I also would coat the inside surfaces with Rust Bullet (not the areas where you have to spot weld back together). I am sure you will only want to do this once ... ever. Is the car going to have A/C? If so, you do not need a hat on the driver side. You could flat-plate it.
Yes, we got the entire A/C system from our donor 75 Maverick. Condenser, lines, A/C-heater box, dash board with vents and the controls. I will be using a mid 90's F150 compressor to fit the accessory brackets we have already refinished. The 75 compressor was junk and I am switching over to 134-a anyway. R-12 is getting too hard to come by even though its a much better gas for refrigeration. Do you have to delete the hat on the driver's side to install A/C? or is it just not required?
Maybe I should have said it has openings on both ends of the cowl lookin from under the dash. Can't really say, hats on both sides, cuz never had cowl off. Having the heater box out along w/ dash tray -- have opening on both ends.
Factory A/C cars have that area stamped, a ridge defines where the hole should be, but it still is still sealed off. Because it is stamped, it can be a weak spot, and mine started rusting a small amount right on that ridge. The A/C box just draws fresh air from the cowl on the passenger side. If running the A/C on Fresh, that is when you are drawing cowl air. On Max, it recirculates the interior air only (in Florida, you better cool the interior air first before trying this .... ). Some folks that have A/C have made the cowl smooth, getting rid of the slats. That makes the cowl even more water-proof. They also report the A/C works good this way, but I will say that in this climate you better have the windows vented a bit to start. In my daily driver, a newer Lincoln, I tend to run around many days with the back windows down an inch and the air on while in town. For those of you freezing right now, that was the protocol just yesterday. Otherwise,sealed up, the car got too hot while parked. Go ahead, start throwing the rotten tomatoes.... lol I don't know how one would run an A/C system, and have a separate fresh air vent for the driver side. Get rid of the far left A/C outlet and just run the air on the center and right vents? Seems pretty complicated ... I would flat plate the driver side of the cowl. Mojo, I am mystified by your driver side being open. That ridge in mine looks like you could knock the inner slug out easily with a hammer. Your A/C is in-dash? not Ford underdash?
Florida based AC cars: The last seven cars we built had the Cowl Slats Removed and Sealed . The hat or hat's were sealed over when we were ' in there ' . Before Sealing we removed any rust , and patched any damaged areas with metal , Coated everything with OSPHO ..waited 48 hours to dry , then applied Fiberglass mat and Resin and after curing coated entire areas with POR . After checking for any possible leaks we welded in the panels at upper cowl areas, then finished off with filler and primer. Painting was last of course but the cowls didn't leak .. and the Vintage Gen 11 ACs all worked splendidly. I usually don't park in the Sun too long unless at a car show where there is no shade . If it's hot when I leave I usually blast the AC on full then lower both front windows about 1/4 inch to assist in evacuating any heated air while the interior is cooling. You're correct .. It gets really hot down here in Central Florida . The AC's in the cars work as well or better than the AC's in our trucks. I've seen several approaches to sealing off the areas under the cowl that are prone to leakage and all of them seem to be effective and STOP the water . Cometized (Chip)
My car is fac AC; has been upgraded to R134. Opening on the drivers side lets fresh air into drivers foot well. I like this feature and wudn't seal it even if I ever remove the cowl. I have a magnetic cowl cover I put on the car when I wash it or leave out over nite. I have not discovered any leaks since I replaced windshield and rubber gasket, even in rainstorms, when I did'nt have the cover on.. Factory A/C cars have that area stamped, a ridge defines where the hole should be, I don't understand what you are trying to convey in this sentence.
Mojo, I am pretty sure you have an "error" car, as in when assembled, they may have put a non-A/C cowl in there, instead of what should be there. If the driver side has an open hole, there should be a manually-operated vent assembly on that side to control the airflow, and that vent empties right where the left A/C vent usually is on a 70-72 car. Since yours is a 73 it likely has the glovebox dash, right? I would think a non-A/C 73-77 normally has some kind of manual vent system on that side. Not certain of what should be there, because I haven't seen many (if any) non-A/C later cars down here. Having non-controlled fresh air coming in that side all time can't be how it was done intentionally.... especially in winter. "Factory A/C cars have that area stamped, a ridge defines where the hole should be." I had a non-A/C 71 Comet before my A/C 72. Where the manual vent attached in the 71 was a hole with top hat, etc. In my 72, the bottom plate of the cowl is continuous on the driver side, but there is a circular stamped area that duplicates where the hole should be. I get the idea that the bottom plates for all cars are all stamped out of the same press first. That area is ridged, and the edge is thin because of the stamping. I get the vibe that it is formed like this so that it is easy to move that piece on to another machine that presses that area out easily for use in non-A/C cars. That way, Ford would only need to have one press to stamp that piece for all the cars.
There is a manually operated vent control airflow entering to drivers side footwell -- a welcome feature in summer w/ long tube headers radiating heat to the floor area. It's not a problem when warm enough to run AC. The car does not have a glove box, might have been built B4 they started putting boxes in - build date, Sept 72.
Wow .... I just by chance looked at your post in the "Garage" section. You have an underdash picture of the steering column, and sure enough, there is the left duct for the A/C and a fresh air vent. Sorry I doubted you, but I have NEVER seen that combo before. I can't imagine this is common.
I was going to suggest look at that pic in my newly submitted garage post. I am glad the subject came up; I wud have thought this was/is common among these cars. As this is the only car of this type I have ever owned - not about to argue w/ folks who have had many over the years. Some other members who have many of these cars may, hopefully, contribute some thoughts/opinions on the issues