A quick "how-to" of a recessed firewall for a hotrod

[Can-Con]

I did this one last week for the '29 roadster I'm working on. All you need is some thin sheet stock.

First, I cut a piece that fit inside the back of the hood. That will give you the exact size and shape of the front of the firewall that attaches to the body. Check it against the opening where the original firewall glues too to make sure it covers the hole and extends far enough around the opening far enough for a good gluing surface

I also made a small, square box, slightly narrower than the firewall face piece but still wide enough to clear the sides of the engine you'll be using. Leave it open at the bottom but close off the top.

You can make the top piece angled like I did or make it square, your choice. But make sure the box will be tall enough to clear the back of the engine and distributor if it's an engine with it on the back.

Trim off any excess plastic from the box and make sure it's the same depth and sits square on the face piece. I usually run it over a large file a few times to true it up.

Position the box on the face and mark around it to you know where to cut an opening. Make sure you leave enough material on the inside of the opening so the box will glue down and completely cover the opening. Again, make sure it's sitting square on the face when gluing.

Test fit again to make sure the part fits the body well and covers the opening. Some more filing may be necessary for the part to sit flush with the bottom edge of the body and still look even around the top and sides. You will probably also need to make an arch opening in the back of the box to clear the transmission. I did this in a couple seconds with my Dremel and a barrel sanding head.

It should also still fit in the back of the hood well. This will keep the hood in position when it's all assembled.

When you're happy with the fit, trim off the excess material around the opening and clean up the edges with some fine sandpaper. You can use it like this but I used some putty to round off the inside corners a bit and also rounded the outer edges some for a more finished look.

A couple shots of primer and your ready for paint

Pretty easy little project for an afternoon.

Namaste my friends.

Edited September 15, 2022 by Can-Con

[Raoul Ross]

I may need to do this stuffing a "348" into the '50 Chevy pickup... Thanx for the excellent 'How-To'! ?

[Leica007]

4 hours ago, Raoul Ross said:

I may need to do this stuffing a "348" into the '50 Chevy pickup... Thanx for the excellent 'How-To'! ?

I'm doing the same swap, engine firewall clearance is ok, but fenderwell  required changing fan belt/alternator to fit. I ended cutting belt (5mm) to fit it in.  Also check radiator clearance, trimmed trans crossmember height to set engine back, but no mod to firewall needed. Hope this helps.

[bytownshaker]

Very well laid out description of how to do a recessed firewall.

[Skip]

Almost looks like the time honored "Ace Hardware Recessed Firewall Kit".  Since at least the early 70's when "Rod Action" magazine ran an article on recessing Model A firewalls with a wheelbarrow body.  They even came up with a few suggested uses for the wheel and tubing that came with it.

Smart idea!  Your idea is great, it works exactly like Hot Roders have been doing for years, even before the introduction of the wheelbarrow.  Guess it's one of those "Life imitates Art" things! LoL!