Firewall insulator

[Y-Blockhead]

Bottom Line Question: What are the specific sizes of the screws / bolts you used to connect the insulator to the firewall inside the car?

Or - What are the specific sizes of the bolts / screws that were originally used on a late 1930 - early 1931 flat firewall Roadster. There are four in question: the one that holds the coil bracket and its twin to the left; and the two below and to the left and right of the junction box, the passenger-side one for the speedometer cable inside the car. With these specs I can get longer ones without destroying the threads of the existing holes.

A complete “firewall bolts kit” is available, but these will be too short anyway.

The proper sizes are not listed in any of the Les books, nor the Judging Standards book.

While the engine is out I’m putting in the firewall insulator. I received it from Snyder’s with a bag of extra-long screws/bolts to hold it to the firewall, but none fit the existing threaded holes. I contacted the manufacturer who sent me a new set of screws/bolts, but these too do not match the existing threads going through the firewall. I even brought the existing screws to Ace Hardware but they do not fit the standard

Are we sure someone in the last 90 years didn't replace your screws with something foreign (metric)?

 

[David in San Antonio]

Y-Blockhead: Nope, somebody, or several somebodies over the last 90+ years might have retapped / forced / otherwise boogered up the holes. I’m wondering what actually belongs there. I may choose to be the next dadgummed son-of-a-bachelor to mess with the holes.
However the bolts / screws that came out of the firewall worked fine, they’re just too short to accommodate the additional thickness of the insulator.

 

[700rpm]

I’ve done the same thing on my coupe. It helps.

 

[700rpm]

I put some 1/4” insulation board under my rubber floor mats. It helps a lot.

 

[700rpm]

I did a simalar thing on my tudor. It helps.[/QUOTE]

 

[nkaminar]

My car has the insulator and a black plastic cover over the insulation. Holes are plugged and there is heavy felt material around where the pedals go through the floor boards. Works good to keep out the engine heat. This came with the car. Not sure where the underlying insulation came from but the black plastic is available from Snyders. There is also insulation in the remaining parts of the car, such as under the seats and floor mats.

https://www.snydersantiqueauto.com/product.htm?pid=977351&cat=0

 

[Y-Blockhead]

My car has the insulator and a black plastic cover over the insulation. Holes are plugged and there is heavy felt material around where the pedals go through the floor boards. Works good to keep out the engine heat. This came with the car. Not sure where the underlying insulation came from but the black plastic is available from Snyders. There is also insulation in the remaining parts of the car, such as under the seats and floor mats.

https://www.snydersantiqueauto.com/product.htm?pid=977351&cat=0

nkaminar, The underlying insulation comes with the plastic cover and is glued on.

The screws that come with the Fire Wall insulator are ¼"-20 and should fit your existing holes, mine bolted on no problem.

I have Dynamat and foil covered jute on my floors along with carpet to dampen the heat and excess road noise in my Town Sedan. With all body parts lined with Dynamat it is quite nice inside.