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Discussion Starter #1
I expect to be ready to start installing my new cowl next week, so I am looking for information on how to best prepare the metal. As we all know they parts are designed to drain water, I want to be sure I properly paint the part to provide the longest life possible.

The new cowl came from CJPP with typical weld through primer applied. First question, is it really weld through and will not contaminate the welds? I want to prime the surface and then apply a paint or coating that will hold up to the wet environment. My car will be garaged when done, but will be driven and I expect see rain at times on long cruises.

During removal of the old cowl panels, I have noted that Ford put some kind of sealant between the layers of sheet metal, firewall to cowl and lower cowl to upper cowl panels. They then spot welded the layers together. What was the material that Ford used and what material can be used today to do the same function? The material looks sort of like a seam sealer, but would have to be a weld through type if there is such a thing?

Removing the old cowl has been a royal pain, I am looking for advice on how to properly prepare and install the new cowl for longest life.

Thanks
 

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Generally panels are shipped with e-coating, not weld through primer. You might want to verify what you've got.
I doubt they put sealer on and then tried to weld through it. I use Evercoat 822 Maxim for seam sealing.
 

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Discussion Starter #3
Generally panels are shipped with e-coating, not weld through primer. You might want to verify what you've got.
I doubt they put sealer on and then tried to weld through it. I use Evercoat 822 Maxim for seam sealing.
I will check my invoice, e-coat is likely but adds on CJPP say weld through primer.
Whatever Ford used, it is between the layers of metal so I would suggest it was applied between layers and then spot welded. The coverage was too good to have been squeezed in after spot welding.
I will take a look at the Evercoat 822.

Thanks
 

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I've used weld-thru primer from a spray can, but it's not really that easy to weld through. You get some popping and not always a nice bacon sizzle sound.

For my sub-frame connectors, I bought some Master Series Silver - found it for sale online.

You could do the lower portion in Master Series Silver and then mark & grind away the spots where you'll weld. Then when the welding is done and you've grinded them smooth, put a top coat of the MS Silver to help seal things up. The MS Silver is easy to work with (I used a foam brush), seals everything well (according to others here) and dries hard and permanently. Then you can paint over it when you're ready.
 

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Yes, Ford did weld through sealer. With the pressure of a spotwelder, it'll displace the sealant in the weld zone. An area like the cowl on the 65-70 cars would be impossible to seam seal after welding the assembly in a production environment. You could potentially recreate the factory method, not sure how it would work with a MIG doing a rosette weld, but it might be worth a shot to try on some scrap.

For something like a cowl, a good method is to clamp the parts together, center punch the location, then use a spot weld cutter to go through the top panel and clean the lower. Don't use one with a drill as a pilot. Hougen and Blair have a rotobroach type tool that works well with a spring loaded pilot. You can also get one of the Dentfix cutters - just be sure to run it slow.
 

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I found the weld through primer not a good thing. I actually powder coated my bottom piece. I used round dots as a masking where I wanted the spot welds. I just used seam sealer where needed after. As a side note make sure the weld on studs that hold the air vent hats on inside the car are welded properly. One of mine wasn't and came loose when putting the driver side air vent on.
 

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I have installed a few, and I definitely separate the two parts to install them. I scuff the weld through primer almost completely off and prime the parts with SPI epoxy. On my '70 project I welded the lower section in to begin with. Ground all the welds down, seam sealed the hat applied the second coat of primer and shot a single stage urethane on all the interior surfaces.

When I went to assemble the upper cowl I used a wire brush in my electric drill to completely remove the paint in the rosette weld holes. The paint makes a mess out of the welds when it gets in the puddles, but it is doable. I had thought about going back and sealing up the inside upper to lower cowl area when I get ready to paint the outside, as there is some access on these cars compared to earlier versions.

Hope this helps
 

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I went on the theory that there was little chance I could keep over spray out of the cowl during final paint and acted accordingly. I used weld through along the joining edges. I used Rust Bullet on the interior side of both halves then, knowing the car would be red, I sprayed Rust Bullet Red topcoat. I then sealed the edges, staying away from weld points, clamped it together and welded it up.
 

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Discussion Starter #10 (Edited)
I have installed a few, and I definitely separate the two parts to install them. I scuff the weld through primer almost completely off and prime the parts with SPI epoxy. On my '70 project I welded the lower section in to begin with. Ground all the welds down, seam sealed the hat applied the second coat of primer and shot a single stage urethane on all the interior surfaces.

When I went to assemble the upper cowl I used a wire brush in my electric drill to completely remove the paint in the rosette weld holes. The paint makes a mess out of the welds when it gets in the puddles, but it is doable. I had thought about going back and sealing up the inside upper to lower cowl area when I get ready to paint the outside, as there is some access on these cars compared to earlier versions.

Hope this helps
Yes, what you have done is closest to what I was thinking of doing. I have a pneumatic punch I can use to create the holes for rosette welding. I like the idea of fully installing the lower cowl panel, grinding the welds flush, and then installing the upper cowl panel. I have been careful to do minimal damage and grinding on the bottom flange of the firewall and side panels. I have become educated as to the ability of rust to invade the space between the overlap seams. With everyone's help and input, I expect that the car will outlive me and hopefully the next owner too.

Quick question, I see a brace across the windshield posts. Was this necessary when removing the cowl or because you removed other structure too? I am removing the flange for the lower cowl at the firewall right now. The last thing I planned to cutout was the section of the lower cowl between the windshield posts.

Looking online, I found this video from 3M, informative. It linked to many others on their seam sealing products and application which I found informative as I have never done this stuff before.


Thanks to all for the input.
 

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I think you can only apply the sealer between the two panels if you use a spot welder. But you can probably do it if you can leave the areas free from sealer where you would mig weld too. I think the clamping force of the spot welder moves the sealer out of the way of the weld area. That is why they say some sealer will squeeze out.
 

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I bought a one piece (upper & lower attached) cowl panel for a really good price. Before I installed it, I took a quart of Master Series Silver & dumped it in the drain hole on one side. I them swished it around all I could, back and forth, then let it drain out the other side . The next day I reversed the order & dumped it in the other side first. Once this dried, I examined all the areas I could see & I can honestly say I am not worried about this ever rusting through again.
 

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"Quick question, I see a brace across the windshield posts. Was this necessary when removing the cowl or because you removed other structure too? I am removing the flange for the lower cowl at the firewall right now. The last thing I planned to cutout was the section of the lower cowl between the windshield posts."

The "brace" was tack welded in place due to me fully replacing both lower A pillars (one at a time). The upper A pillars were hanging out in the air at one point in time. I also installed a full roll cage along with several braces across the cowl and tied them all together. Having the cowl completely off really helps with the knee bar instalation. There is no need to brace the windshield area, as long as the car is properly supported by jack stands, and your lower A pillars stay in place.
 

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Just going to throw this out there, if you are using any of the "rust encapsulator" paints, be sure to have lots of ventilation if you weld around them. I got a little too close to the POR15 when I did the floors on my 71 and felt like complete crap for a week.
 

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I had mine done at a local shop - he replaced the bottom only, reusing the original top. I had him prime, seam seal and finish paint every inch of the panels - top and bottom. This is not concours correct, but I don't care about that - I just don't want to ever go through this again......
 
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