Ordering sheet metal for firewall patch -- what gauge metal to order?

[bobs73challenger]

Hi everyone,

I'm looking to order some sheet metal today.  A friend of mine is patching the part of the firewall where the brake booster mounts and the bulkhead connector comes out and a couple of holes in the inner fenders. 

We're ordering metal, not replacement sheet metal parts, but sheet steel from a local supply shop. 

Was wondering if anyone has any input on what gauge metal I should be ordering.  I bought a caliper this morning, but the results I'm getting are somewhat inconsistent.  I've getting results ranging from 16-22 gauge, which is a ballpark that I would've guessed, but there is a large difference between 16 and 22. 

As always, your help is appreciated!

[glovemeister]

I use mostly 16 gauge. In some spots you will want 18. You may want a piece or 2 of 20 ga. But the vast majority of it should be 16-18ga.

[jimynick]

16 is a biotch to hand form. 18 would be a good compromise. 22 is for Kia fenders, don't use that in a stressed area. We used to use 20 for general patching. Consider galvanized as well. The satin coat stuff works pretty well, you just have to grind it clean where you weld it. Just my 

[AARTA340]

16 is a biotch to hand form. 18 would be a good compromise. 22 is for Kia fenders, don't use that in a stressed area. We used to use 20 for general patching. Consider galvanized as well. The satin coat stuff works pretty well, you just have to grind it clean where you weld it. Just my