Lower Cowl Repair Question

mach&roll · Jun 28, 2022

Hi everyone--new member, first time posting. I'm an old AMC guy (don't laugh) who has mostly done AMX resto's. Got a good deal on a 72 Mach 1 that is all original and very solid with exception of the passenger floor pan and the passenger lower cowl. I've never done a complete Ford project before so sorry in advance if I ask some dumb questions.

Anyway, I have the car tore down and on the rotisserie and almost ready to start metal work. I noticed that we can buy complete repro upper & lower cowl kits but honestly everything is solid/intact on my car except for the passenger corner of the lower cowl where the heater box mates up. Basically everything is gone right there.

I noticed they make a 65-68 lower cowl repair patch kit for about $90. Has anyone tried to make those work for 71-73 models?

Obviously there would be a lot of cutting/bending to mate it up but it would probably be less work that fabricating from scratch.

Appreciate everyone's thoughts on this.

Thanks.

giantpune · Jun 28, 2022

IMO, the more of the original metal you can leave in place, the better. If you can get away with patching it and not pulling the entire car apart to replace the full upper and lower cowls, then thats definitely better. It would be a matter of how big the rust damage is and where is it at exactly. If you can get to the spot to weld it up while its in the car, I say go for it. Even if you can't get it perfect, it doesn't matter. The floors get covered with carpet and the lower cowl is hidden behind the dash.

Mister 4x4 · Jun 28, 2022

I actually cut and grafted-in pieces from a '72 (entire front clip, upper & lower cowl pieces, and parts of the forward floor/firewall area.

And I did all of that about a year prior to Dynacorn releasing new replacement upper and lower cowl sheet metal for '71-'73s. Check with the usual vendors, like Ohio Mustang Supply, National Parts Depot, CJPP, et al. Even if you get the lower piece to just cut -n- graft the bad spot, you're ahead of the game.

Kilgon · Jun 28, 2022

First, welcome from Ohio. Glad to see that you are a new owner of pony. My cowl was rusted at the same area. I decide to remove the top half due to a lot of surface rust across the entire bottom half of the cowl. I ended up cutting out the bad area and made my own patch and hat. As mentioned it's out of sight so it doesn't have to be perfect. If the area isn't too big you might be able to patch it from underneath inside the car.

mach&roll · Jun 28, 2022

Appreciate the replies and advice.

The right corner of my lower cowl is completely gone with just a big gaping rusty hole left--can't even tell where the hat used to be. Odd thing is the rest of the upper and lower cowl is in really good shape with the original factory paint still on it so I hate to rip it all apart. I'm sure I can repair it from underneath by either fabricating something or using fiberglass.

It doesn't sound like anyone has tried to make the 65-68 repair patch work as a fix for a 71-73. If not, does anyone know if the cowl hole size is about the same across all model years?

Thanks.

c9zx · Jun 28, 2022

Welcome from Oklahoma. Not laughing about AMCs, they made some cool cars. There is another AMX fan on the site as well. Chuck

mach&roll · Jun 28, 2022

Good to know--not many AMC guys out there. I've enjoyed working on them but just can't hardly find parts anymore and the ones you do find are crazy expensive. I always liked the sportsroof Mustangs--this Mach will be a fun project. Already amazed at all the information and parts that are available.

Jack

mjlan · Jun 28, 2022

My 72 just had rust damage to the area over the heater box also, somebody had already cut an access hole in the upper so that they could shoot expanding foam and tar around the rust to stop it leaking. This is what it looked like after I got all of that mess removed.

You could partially remove the upper cowl to expose the area of the lower that needs repaired and repair the lower and not replace it if your upper is in nice shape.

7173Vert · Jun 28, 2022

I would love to own a Gremlin, 4-spd, 304ci... I had the pleasure of driving one as a company car in my early twenties, that thing could fly... I keep my eye's peeled in my area for one.

Vinnie · Jun 29, 2022

mjlan said:
My 72 just had rust damage to the area over the heater box also, somebody had already cut an access hole in the upper so that they could shoot expanding foam and tar around the rust to stop it leaking. This is what it looked like after I got all of that mess removed.

View attachment 65029

You could partially remove the upper cowl to expose the area of the lower that needs repaired and repair the lower and not replace it if your upper is in nice shape.

I went in exactly the same but I put in a new bottom patch without a hole coz I don't need it with aftermarket airco. If I did need a hole and a hat I'd have fabricated it myself.

CrazyHorse · Jun 30, 2022

I bought the full upper and lower dynacorn panels years ago an stuck in in the corner.... just now getting around to thinking about pulling my front clip off to get to the places on my car that need replacements. That bad thing is that at that time they didn't sell a cowl for an AC car, which mine is.... and I still don't think it's made.

Looking now at how difficult this is going to be, because finding people to do sheetmetal work is almost impossible it seems.

tony-muscle · Jul 1, 2022

You can check how I went about it using the hat kit for the earlier Mustangs: https://7173mustangs.com/threads/my-method-for-cowl-repair.30508/
From what you describe you may have to fix a larger area than what the hat covers.

Mister 4x4 · Jul 1, 2022

mach&roll said:
Appreciate the replies and advice.

The right corner of my lower cowl is completely gone with just a big gaping rusty hole left--can't even tell where the hat used to be. Odd thing is the rest of the upper and lower cowl is in really good shape with the original factory paint still on it so I hate to rip it all apart. I'm sure I can repair it from underneath by either fabricating something or using fiberglass.

It doesn't sound like anyone has tried to make the 65-68 repair patch work as a fix for a 71-73. If not, does anyone know if the cowl hole size is about the same across all model years?

Thanks.

Why would anybody do that when there's a '71-'73 replacement panel available? Even if you don't want to replace the entire panel, you can cut out and replace just the pieces you need. I would've killed for new panels, rather than having to do it the hard way.

Here's what was left of mine:

Here are the patches from the '72 junk yard parts car I found (I had to reassemble the hats because the yard guys cut right through them when I'd come for the front clip several months earlier (not knowing how bad the cowl was - I should've just had them cut through the A-pillars and got the whole firewall):

Welded, sealed, cleaned, treated with Rust Bullet:

All closed up:

Finished with that, move on to the next part:

71ProjectJunk · Jul 1, 2022

If I was in your situation I would get the lower repo cowl panel and just cut what I need from it and try to weld it from the bottom. Since you seem to have a nice hole there right now I would get my hands in there and clean all the rust in there and coat everything with POR-15. After all the POR-15 is done I would lap weld the new piece I cut from the new lower cowl panel into place. After it is all welded I would go back from the top with a lot of seam sealer and seal it all. It may not be a bad idea to open up your upper cowl like Mister 4x4 did but just on the passenger side and only as much as you need to really get in there and seal everything off after you weld everything in place. Just cut maybe a 6 inch by 6 inch piece off the cowl in three parts of a square so you can just pull it up from the part of the square you did not cut, without taking the piece off, just bending it up.

Mister 4x4 · Jul 1, 2022

It would also be a good idea to get a light source in there on the driver side and look up through the bottom, just to make sure there aren't any pin-holes you can't see otherwise. Hopefully, you can get away with just doing the passenger side, but I've not seen too many that if one side was that bad, the other was just fine.

rcadd1ct · Jul 2, 2022

Since I went with classic auto air I no longer needed the vent. I was able to lay in a pice of lexan and seal it in from the cabin side.

I then used eternabond (permanent flex seal used for mobile home roofing) on the cowl side to add a second seal

Mister 4x4 · Jul 2, 2022

Well... that's one way to do it. Nice job!

rcadd1ct · Jul 3, 2022

Mister 4x4 said:
Well... that's one way to do it. Nice job!

Thx.

mrgmhale · Jul 5, 2022

c9zx said:
Welcome from Oklahoma. Not laughing about AMCs, they made some cool cars. There is another AMX fan on the site as well. Chuck

I also like both the Javelins and AMX pony cars. My favorite for style is 73-74 AMX models with their rounded corner quadrilateral taillight pods. My older sister had a 74 AMX with a 360, and all the good options (A/C also of course). Once in a while when she would hit the sack early my younger brother and I would sneak her keys from her purse and take it out for Wednesday night cruising on Van Nuys Blvd, in Van Nuys, CA (1973-1974 era). Even though it was a bit smaller than the optional 401, her 360 4v equipped AMX was still one very fast car. If parts were more available I would be tempted to get one to bring into the midst of our current collection of pony cars.

It is hard to look at the 71-74 AMX and not see the similarities to the 71-73 Mustang. Their wheel humps, and the trailing edge of the roof with its Flip Tail really brought some cool style to their appearance. And the interior cockpit was really nicely done.

MaddMike · Sep 2, 2023

I need some guidance please. When my 71 Mach1 was repainted, I had a bad passenger side lower cowl vent. In 1998 nobody (I was aware of) made a cowl replacement panel like they do now. So the body guy cut away the rust and fiber-glassed it. Which worked fine. I noticed about a year ago the fiberglass had cracked and when water gets in there I have a small occasional drip. Then last week I flushed the radiator. Since the car had been in storage for 20+ years with straight coolant all that time I needed to replace it and mix it with water. When I finished the final (6th) flush, I noticed hot water dripping from the plenum drain - SON OF A BITCH! The heater core was new when I restored the car so I can only conclude the Prestone turned acidic and ate through or there is a minor crack because on the final flush drive I jumped on the gas so the pressure would have increased. Since then, there is nothing else emerging, it is dry and the new fluid is in it and fine. BUT I gotta dig in there this winter to replace the core. So while I am at it I will replace the cowl because it is going to have to be done sooner or later. SO MY QUESTION IS - can I replace the cowl with the engine in the car? I have no appetite to remove it. I figure remove the dash, the windshield, the hood, the fenders and the export braces. It would be more difficult without being able to stand in the engine bay. But can I get some expert opinions please

Lower Cowl Repair Question

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