1966 Chevy Chevelle Firewall Smoothie Panel - Smooth Backdrop

Now it's time to start welding the panel in place. After getting the settings right (see sidebar), we put a small tack near each Cleco. Even though the panel is very thick, running a constant bead will produce too much heat and could cause warping.

The best way to keep the heat down is to put a tack, move about 3 inches and put another tack, working all the way around the panel. By the time you get back to your first weld the area will be cooled down and ready for the next tack that should be made between the first and second tack.

ABC also provides this lower piece to go along with the large panel. Weld it in with the same tack-and-move procedure.

After you have all the tacks completed, grind off the excess to see if you have missed any spots. At this point we were losing our light so we stopped and primed the area to prevent rust while it sat overnight.

We were using an air grinder to knock down the welds and found having an assortment of sizes really helped get into the tighter spots, like around the booster area. A medium-sized arbor with a larger disc will conform to the grinding surface...

After all the grinding was complete, it would be time to use some body filler to smooth out the edge. Since we want to do all the bodywork at the same time, we decided to stop here. Again, to prevent any rust from forming we coated all the bare metal with the primer.

Even without the final blocking process the panel is super smooth and will be the perfect backdrop to the big-block that will eventually find its way in the engine compartment.

Here is a close up shot of the top edge. As you can see, it won't take much filler to get it perfect.

Before pulling the trigger on your MIG gun, you best get the settings right. The first step is to use the reference guide found under the door on most welders like our Lincoln SP-100.

With our 0.025 wire and 18-gauge metal thickness, we set our wire speed to 5.5 and our voltage to G. Our voltage is a bit under what is recommended because we weren't sure how the thinner factory firewall would react. This worked out perfectly for tacking the panel in place.

We did a few test tacks creating problems you might come across during set up. Starting from the left, this is a good tack. We have good penetration and the weld is nice and flat. Moving right is a low voltage situation; no penetration and the gun handle pushed back against our hand as we welded. Next, we have a no gas problem that you might encounter when you run out of shielding gas or welding outside in the wind. Lastly, we have a too much wire speed issue. The welder is just putting down too much so the weld is very tall above the surface. We still have good penetration, but this will waste wire, grinding discs, and your time.