Is 20 guage too thin for smooth firewall

[scherp69]

So on the weekend I made a smooth firewall out of 16 guage sheet metal. I was going to weld it on top of the old one (most of it removed though), then I got thinking and now I'm wondering if I would be better off running a flange all the way around, using thinner sheet metal so it is flush with the flange and saving some time trying to smooth the edges. Right now it's just held in place with cleckos. I've done a search of the threads and found different guages of sheetmetal that have been used, but none of the threads found have mentioned running a flange at all. I ran a test flange on a spare piece of sheetmetal and found that 20 guage fits pretty flush. 18 is a tiny bit too thick, but would probably work with a little grinding.

Or...do you think I would be better off leaving if the way it is now. The more I look at it, the only places I would have to grind to make it fit a contour would be along the top and around the tranny tunnel. The other areas would blend in pretty good. What do you guys think???? Here's some pics of what I've done.

https://static1.pt-content.com/images/pt/2008/09/PICT00095-1.jpg

https://static1.pt-content.com/images/pt/2008/09/PICT00105-1.jpg

https://static1.pt-content.com/images/pt/2008/09/PICT00124-1.jpg

https://static1.pt-content.com/images/pt/2008/09/PICT00165-1.jpg

[MarkM66]

I think 20 would be fine. JMO.

[ProdigyCustoms]

For warpage and vibration we use 16, but 18 or 20 is fine long as you plug weld it along the lower cowl as you have it set up.

Your doing it exactly correct.

[Fireeater]

Here's a dumb question. How are the heater hoses deleted after this is done? I wanted to do the same thing.

Dave

[scherp69]

Thanks Frank. I think I'm going to end up leaving it as is then.

Fireeater....I'm going to install a Vintage Air system that does not use the same set up. I'm then going to route the houses through the passenger side cowel panel like Frank did on project EmptyNest. The other option is to use a bulkhead. Here's a link to what it looks like: https://www.pro-touring.com/forum/showthread.php?t=41697

[BRIAN]

20 is too thin for a flat sheet. If there are no contours or bead work. 16 and 18 are close but big difference between 16 and 20 gauge.

[scherp69]

Thanks Brian. That's what I was worried about. I've decided I'm going to stick with the 16 guage one that I've already made.

[protour73]

Here's a dumb question. How are the heater hoses deleted after this is done? I wanted to do the same thing.

Dave
remove heater core from the heater box inside the car, and use pipe plugs for the holes in the intake and water pump.

[2Bad4Ya]

We just put a piece of 18 aluminum on top of our firewall. I patched/closed up all heater openings etc... then used fuzor body panel adhesive to bond it to the firewall. Then used SEM hi build epoxy sealer along outer edges, and sanded/blended smooth. The firewall cover should do fine with flexing, etc... with the bonding/sealer method. Then again I am talking about a cover piece, not using the panel as the firewall itelf.

[scherp69]

So I ended up using 16 guage for the whole firewall. Here's how it turned out. I still have to clean up all the welds. I plan on putting the wiper motor under the driver's side fender.

https://static1.pt-content.com/images/pt/2008/09/PICT00282-1.jpg

[camaro2nv]

Nice job!