How should I fill firewall holes

[gigamanx]

Originally Posted by dsraven

try

https://www.welderseries.com/

on line for some sheet metal plugs for cheap, or shop locally. clean the area well first, then if you grab a cheap stepped drill from harbor freight or whatever you can get a bunch of plugs the same size then drill the cab hole to fit the plug. that way the hole is nice and clean for welding. you can use a copper plate behind so if you have a little burn through it will stay put (weld doesn't stick to the copper). do a series of tacks around the plug, say 2 or 3, then carry on to the next plug because if you weld the whole thing at once you will warp the firewall or wherever you are welding. tack then move on, come back and extend the tack, then move on to allow cooling. soon the plug will be done. you can wipe with a wet rag to help cool and shrink the area so it doesn't warp too bad.

See now this is why I asked all you fine smart people... Funny they are called unholes. Here I was thinking I need to cut perfectly shaped pieces to fit in all manner of crazy spots on the firewall. I did not think of my step drill bits.

Originally Posted by bowt1ed

I just cut out slightly over-sized sheet metal circles, cleaned surfaces/edges, placed on the inside of firewall (helper to hold tight against), and welded from outside. With that thin a gauge, not too much filler required. As I recall, filled around 45 of them.

Cheers, Jim

That is a ridiculously smooth firewall. Nice job!

https://www.welderseries.com/Unholes-p50202282