Projects Model A Firewall clearance

I’m concerned about the removal of a SBC distributor using any of the after market firewalls. I’ve built several model A’s, with this type of firewalls, luckily I never had to replace the distributor, but it would have required the engine to be removed. Any suggestions or pictures would help!

 

I went with the flip. Not as nice looking but I needed the valve cover room and I’m not that tall so the lost leg room wasn’t that big a deal for me. Plenty of room to get the distributor out. I have pics but phone wouldn’t download them. Will try another devise if no one else responds.

 

The few that I have done I built the firewall myself to ensure it has the clearance I want and where. That said on a ‘28-‘29 I’ve had to unbolt the trans and jack it up a inch or so to get the dizzy to clear. In hind site that’s not very ideal for a side of road repair.

 

Made my own firewall recess in my Model A based on the same size that the original builder made... as my car was originally built in its current form sometime in the 80s.

The pic with the engine in is the before pic, but I made my the firewall recess the same size. For some reason, they used 22ga sheet and I don't think they had a sheet metal break, presumably because that is what they had available. I made mine out of 14ga sheet metal.

Never tried to remove the distributor with the engine in, can I cannot say for sure that it has enough room for removal. Also, mine is a Sedan, so there is plenty of leg room.

 

We used a Bitchin' firewall on my son's '31 Model A. For distributor clearance/removal we put in a section of 18 Ga. steel curved around a 6 inch pipe.....at about a 30 degree angle just behind the distributor. Do not have a better photo.....




Maybe this photo is a bit better.....

 

We used a stock reproduction firewall and cut the section where the distributor and valve cover would be, and moved it back 4 1/2”. Then made a filler panel for it. There is just enough room to get the valve covers off. The distributor has to have the cap off to install or remove.
Boling Brothers makes a panel similar to mine. I think it’s 6” deep.

 

I just lengthened the frame and moved the motor away from the firewall.

 

Only pre-'65 SBCs and distributors will fit an A.

 

If its a 30-31 model A just take the stock firewall out and turn it around backwards and reinstall.

 

28/29 or 30/31? They're quite different. Stock Model A frame/wheel base or something else?

On my 31, I built a 2 inch recess that flowed along with the stock angled beads, but instead of square 90° brakes, I split 2-1/4 inch exhaust tubing lengthwise into quarters and welded them in to create a round radius going in and then back down. It looks more like a stamping that way. A 32 firewall with a little work, fits nicely in a 30/31 as well.

 

If it's a '28-'29, you can just cut a crescent out of the top & bottom flanges.

 

I can, and did, pull the dizzy in this 276 DeSoto Hemi to put a Pertronix in it with room to spare. No firewall setback, it's a '32 frame and '32 radiator in stock location.

 

Don't forget that 32 frame, with it's 106 inch wheel base, that you and I have under our Model As gives us 2-1/2 inches more engine clearance than a Model A frame, Gary. Coincidentally, an early Chrysler hemi (w/BBC water pump) is nearly the same length as a SBC with a short water pump. Ask me how I know.

 

Bought this firewall as a replacement for the badly hacked up one that was in the car. This one already had the "standard" 30-31 cut and a 5" recess added. I had to extend the corners to clear the Cadillac valve covers, but reduced the recess to 2-1/2" as that's plenty of room to R&R the distributor with the cap removed...

 

Stock wheelbase, 2 1/2" recess. Cap off, enough room to pull distributer.

 

I like the look of your roadster very much!

 

Very nicely done. Looks like it Henry made it that way.

 

Looks great, should solve my clearance concerns.

 

Marty Strode has a thread on building a '29 roadster pickup, find that thread, he shows how he modified the firewall to be able to pull the distributor.

On my 30 the firewall is modified like the one @D-Russ posted. When I pulled the distributor in order to change the intake manifold I had to pull the motor mounts and lower the front of the engine far enough for the distributor to clear. I also had to drain the radiator and pull the hoses, but I didn't have to remove the radiator itself. Kind of a bitch, but how often do you pull the distributor anyway?

 

Here, scroll down this page: https://www.jalopyjournal.com/forum...strip-b-sr-build-marty-strode.1177811/page-24

But really I recommend you go through the entire thread, watching how Marty tackles problems and fabricates is truly educational and enjoyable. The guy is a master.

 

On my '28 coupe a PO made a removeable hatch above the distributor for removal but if you pull the cap and rotor it will come out without removing the hatch door. Maybe he was planning on using a Vertex mag. Note that the firewall mod is aluminum and bolts in. Interesting and creative, I won't be changing it.


For my roadster I made a recess that just does what I need, no big boxy recess, and radiused corners. Like D-russ, I followed the style of the stock one (somewhat). Mine's unfinished, I hope it comes out as nice as his!

 

OK, it's important to note that there are infinite variables involved in creating a firewall recess that will allow removal of the distributor with the engine still in the car. Just off the top of my head there's wheelbase, amount of channel, engine position forward or back, engine position high or low, mechanical or electric fan, front cross member position, depth of recess, angle of recess, type of distributor, cap/rotor on or off, etc.

The recess I built for my car when it had a small block Chevy did in fact allow for removal of the distributor with the engine in place, so @Blues4U , your recess was apparently not like the one I posted.

Measuring and planning are important to ensure everything fits, works together is serviceable in the end.

 

This is true.

But according to this photo, I have my doubts you could pull that distributor out.


Here is mine:


It's possible my engine sits at more of an angle than your's, but as far as clearance, they look pretty much the same. Maybe it's just a bad photo...

 

Take a closer look – your engine sits higher than mine as evidenced by the space between tops of your plug wires and your recess. Looks to me like about an inch or so of space. There's probably 2-1/2 to 3 inches of space between the tops of my wires and the recess. Like I said, measuring and planning are important to make the vehicle serviceable. With the cap removed, I can easily pull my distributor without doing anything else for clearance.

 

To recess the firewall, I used an old Freightliner radiator tank but probably any similar size big truck copper/ brass radiator tank will work. They are stamped steel and bolted on.

 

Here's my set back roughed in I could get the distributor out with out the cap, but I haven't had to try since I put in my 2x3 rochesters. (or is that 3x2)

Phil

 

this has the frame lengthened about 1.25" and the dizzy will just slide out if you take the cap off.

 

Yep, no clearance issues with 31 on 32 rails. Just a Bazillion other "challenges"

 

Thank-You very much.

Thank-You. There are a couple of caveats that go with it. First off it's only a 2 1/2" recess. Rulers and straight edges are more accurate than memory. Secondly, the body came with no firewall and most of the hood lip hacked off, so the face of the firewall only protrudes an 1 1/8" from the little drop where the back of the hood fits.
Firewall and recess were beat out over a couple of hammer forms using 16 ga. hot rolled. (Didn't know any better at the time.) I put a small lip on the firewall section where it meets up with the recess. The recess has a 2" radius.