It is all too often that a builders and hobbyists alike of the Hot Rod industry will find it necessary to make modifications to their Firewall. This is either to recess that engine in a little further, or it could be simply to make for a smooth clean look under the hood.
First, you need to decide what you need to do as far as how you want your firewall to look, where you want to place it, how your going to attach it, and how your going to design it.
For this case, I have a 1935 Ford Pickup and wanted to set the firewall back to even of the top portion of the original firewall drop down. Thus, Ill remove the previous hacking from previous owner, yet I will still retain some of the original looking lines of the firewall. This incorporated a recess of 3 inches from the original placement, and I added a inner recessed portion of 2 more inches for a total of 5 inches for future motor installation
clearance. Do keep in mind that as you recess the firewall back, the further you recess it, the more engine space you'll create. This also has the adverse effect of taking away leg room space and pedal placement space in the cab. So take this in account. Especially you you have a Pickup, and cannot set the seat further back. It is helpful if you have the engine your planning to use and you set it where you want it and cut the old firewall away before taking any measurements. This is what will dictate the creation of the new firewall. The frame needs to be leveled at this time (front to back, and left to right) before placing the engine in, or starting he firewall.
So lets get started:
I needed a way to attach the old to the new, so I used seaming pliers to make a lip to put the new sheet metal to the old. This could easily be butt welded, but using the seaming pliers I made my own pliers out on the milling machine of a set of vise-grips and some blocks of steel that was actually an old three point hitch from a tractor. You can purchase these for about $30 after
shipping. My cost was $9 and it took me about three hours. I usually have more time than money. I removed the firewall from the portion it kicks out and down. I hammer and dollied it flat, and using the seaming pliers, I made a lip to place the new metal flat with the old sheet metal. Here is a picture of the pliers I made, and the portion of the firewall I'll be keeping with the lip bent into it.
I made the firewall out of 10ga sheet so it will be thick enough to not rattle. If I was to use thinner, I would've rolled some beads into the pieces on the sides to keep the rattles down. Its made from 8 different pieces. I made the recess panel first. It still needs a circular cut-out on the bottom to clear the tranny. But that comes later. I blocked it up and leveled it on the bricks. The recess is bent to form the recess, then has 4 little triangle pieces to fill the gaps at the top. Then I made the top piece to span the gap from the old firewall to the recess. Then the side pieces were started with a small lip, it curls inside for floor mounting. Then ground to fit perfectly. Its all tacked together here, and I'll take it out to weld it all up and install 1/2 portion of the tranny tunnel. It slides in and out real easy, will be a shame to make it permanent.
Here's a few pictures after it is welded up, the welds are cleaned up, and I have made the steering column mount. Its out of the shop, and the entire thing will get smoothed up on that top weld after I have the entire truck sandblasted. Brrrrrrrrrrrrrr!
Total cost so far for the whole thing is: looking at the receipts.. $9.24 for the crimpers $5.91 for three grinder wheels $25.00 for the recess , cut and broke $18.55 for the top piece, two side pieces sq. cut and broke $3.84 tax $1(???) for weld wire I used and gas(figure a small bottle worth at $18.00 Argon/CO2.
Lessons learned/ability to say I did it all myself, PRICELESS!