So on each side is a cowl "bowl, I'll call it". I've ordered a new on for the passenger side and I'll repair/replace the damaged areas from the new one - all other parts of it are actually very good and solid so no sense in replacing all with recycled steel when the majority would be original steel. My question is the cowl openings on the front, little oval openings. My drivers side had a plastic/rubber cap - passengers side did not and I'm guessing just gone over the years. In my mind I'm thinking they need to be there to keep the balance of high/low air pressure so I get the right flow into the cab - any other opinions out there or reasons why I should or should not get a cap for the passenger side?

 

Without it would be a great way for many critters to live. The seals along with the hood to cowl seal keep heat and under hood fumes out of the cab air intakes.

 

My '77 had none, they work fine. It does have the bottom opening on each one though. If Ford put plugs in them, must not be for air flow. I'm thinking cleaning access with a small vac hose?

 

Those lower openings are just for access to cab mounts, not connected to cowl. I think OP means the rubber ovals that are in the upper cowl box area just under hood edge. I'd have to go out and look, think some years may have 1 in center. All above the firewall flange.

 

X2 those little metal doors on the front of #112A70 are just to access the cab mount hdwr bolt heads.

 

I'm sorry ... I meant these that are openings in the very bottom. I should have included this pic. I was posting those other pics to show OP that eventually Ford stopped putting the oval openings in the front upper side that they were plugging.

 

@tbear853 Right that is the part - I did look last night and you are right that corner is open, maybe just for moister drainage but I am referring to the oval plastic plug on the front side of those - my thinking is that is you are pulling fresh air from vents on top of cowl (windshield area) which would be like high pressure, if I leave those oval opening open it might diminish the pressure and you'd have low flow coming into the foot vents/heater core

 

My truck once was just heated with the vents, but I don't recall a means to stop air flow from the cowl vent into the heater on the passenger side so might always be open and air flow into the actual "people space" controlled by a door in the heater box as controlled by heater controls? I just don't recall. I know that the passenger can open or shut their vent under the glove box "at will".

I changed it to factory AC long ago. With the factory AC, there is a spring / vacuum operated door that can shut air flow off at the passenger kick panel opening.

My truck has it's original driver side kick panel vent too, it has a a sliding door of it's own. I don't recall if it was on AC trucks though?
I don't think there was one there on the donor vehicles I stripped for parts..

I know about those oval holes, I even thought about adding something like them for cleanout, but after cleaning mine out ... I decided not to. I have seen some have a third oval hole with plug behind the air cleaner into the cowl under the open vents just above.

Somwhere in late '76 or early '77, Ford quit putting the flat shielding behind the front fender between the wheel opening and cowl bowl area which served to cut down on air pressure hitting the door seals too,... and started using large molded whole front fender well shields that shut off a lot more areas of splash and windage.

 

I ordered a new cowl bowl and it came as solid and not oval cutout like original. So maybe the ovals were just something for access reasons.

 

FWIW I cut some round holes in the front of mine 2-1/16" on both my dentsides as I had a huge amount of debris to clean out from each. Water wasn't draining so it was just leaking into the cab. I can easily get a shop vac in there now, plus compressed air from different angles. It was pretty incredible how much had built up in those bowls; had moss growing in there and everything. Put some plugs on the cleanouts but otherwise they need to drain through those lowest points.

It was equally interesting to see how effective that presumably galvanized metal has been to prevent rot forming underneath that moss.

 

As far as I can tell, aftermarket A/C systems (e.g. Vintage Air et. al.) do not use the fresh air intake system that this is a part of. Thus, one could block off the air intake between the windshield wipers or re-purpose it as something more useful such as a cold air intake system for the engine. Has anyone attempted this and documented it?

 

My 79 does not have the oval plugs either. I just had the front clip off and got a good look at my cowl bowls, both sides were absolutely packed with dirt and leaves. Took a good 20 minutes flushing and douching out from above and below. I got lucky that they both seem solid metal still. A couple more years and maybe they would not be.

 

Thanks for all the discussion, late in returning to the thread - my fault. I did buy an aftermarket bowl, replaced it - it did not come with the oval cutout but did have the bottom corner all cut out and beveled down for drainage so I welded in as it came. Don't think id ever know any difference anyhow.