I do restorations on 4-6 classic/show cars a year that includes floorpans, kickpads, wheelwells, trunk panels, etc., & all restoration welding is with .023 wire & C25 Ar/CO2. Auto sheetmetal is quite thin(usually 22-24ga) although some of the older classics('60's) were 18-20ga & much easier to work with. Dave(whateg0) is quite correct with his summation to your query. Lose the flux-core & get some .023 & C25 & your success will be attained by doing practice on some scrap pieces the same thickness as you will be using. The metal has to be clean & bare to get a good weld & any rust will be detrimental to your efforts.
Once you get your wire/gas setup configured & some practice on scrap, your technique will determine ease or difficulty. You must maintain awareness that you will not be able to run continuous beads with auto sheetmetal.... tacking only. I also use varying lengths of 1 1/2" aluminum angle as a backing to absorb heat & provide a solid platform for the weld to adhere & reduce burnthru. It takes PRACTICE!!! Also, you will have better results by tilting your MIG gun to a sharper angle & this will allow your puddle to be flatter. You have to TAKE YOUR TIME!....hurrying will not produce optimum results.
Lastly, being on a shoestring budget will not enhance your success because you limit your variables and investment for a long-lasting repair. What good is a repair if it only lasts a couple months? If your goal is reselling, then go ahead & do the shoestring budget, but don't look forward to incoming recommendations as to the quality of your work. If this is for yourself & you plan to keep the vehicles, do a first-class repair & you will won't regret your xtra efforts. Also, if you maintain the namesake(Techmaven), your membership "handle", just do some homework & search the vast amount of information regarding auto metal & restorations to enhance your knowledge level for this kind of repair. Anyway, just MHO & experience with the classic/show car restorations I have done. Good luck.... Denny
Complete weld/mach./fab shop
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