Firewall Sealing

[836dstr]

I am changing the throttle cable in my Roadster to a conventional linkage with rod ends/rods/bell crank, etc.

There is a slight arc as the rod from the throttle pedal to the bellcrank passes throught the firewall so the hole in the firewall will be slightly elongated. The rod is 5/16 dia.

What would be the best way of sealing this gap?

Is there any type of fire proof boot?

I was thinking about using an oversized washer with a 5/16 ID that would float with the linkage but be retained snug to the firewall with a type of cage.

One other thing. The linkage penetrates the firewall at about the centerline of the Carb.

Any thoughts would be helpful. Thanks,

Tom

[JackD]

A fender washer that is a tight fit over the rod, and held against the rear of the firewall penetration with a coil spring over the shaft is less likely to get stuck like a slider behind anything else.
The light spring tension can also be included in the return feature that you need. 

[jimmy six]

There are "bellows/boots" available from McMaster-Carr on line down to 1/4" .  A fire proof deflector on the the engine side and a bellow/boot in the the drivers compartment to seal air from coming thru will protect you in a fire. If needed I can draw you a picture ...JD

[836dstr]

Thanks Jack and JD,

I was planning on checking the McMaster-Carr catalog. Almost time for my weekly order!

Tom

[Stainless1]

a scrap of firesleeve sandwitched over the hole will work. 
change to morse cable is another option...

[interested bystander]

Just got the Speedway Motors CIRCLE TRACK catalog today (heaven knows why THAT one) and they have some neat thru firewall devices from 1/2" to 3/4" that have a substance that with heat, tightens up- unlike females- (EDIT IF REQUIRED) .

[836dstr]

IB,

I received the same catalog and saw the sleeve & putty combo. After sorting out the throttle pedal/rod/bellcrank/rod to carb geometry I was left with 2 planes of motion for the rod going through the firewall. The resulting hole resembles a large kidney bean. Incorporating ideas from both JD and Jack I found that a 2" stainless fender washer on the rod would cover the hole through the range of motion. I welded up some .200" x 3/4" bar stock into 2  4" square "spacers" and made 4" aluminum cover plates with the coresponding kidney bean shape. I glued some header wrap to one side of the washers leaving the center hole slightly undersize to further seal the rod. Finsihing off the installation is a small coil spring on the rod between the washers that exerts enough pressure on the washers to "seal" them to the cover plates on both sides of the firewall. It all moves freely and offers double protection.

Tom

[JackD]

You didn't bid this job I hope.   

[Dean Los Angeles]

http://www.speedwaymotors.com/p/6848,908_Fire-Stop-Sleeve-Kits.html

FIRE STOP SLEEVE KITS
These fire stop sleeve kits allow you to run wires, hoses or cables through your firewall or any other bulkhead. They include a  unique intumescent putty which when exposed to hight heat, actually expands and seals off smoke, fumes and flames. Fire stop sleeve also reduces the amount of gas and fumes that enters through the firewall under normal operating conditions.

Approved for use in NASCAR, SCCA and IMCA competition.

Choose 1/2", 3/4" or 1" sizes. Total cable or wire size needs to be half the diameter of the sleeve.

These days I don't see too many words I'm not familiar with, but intumescent was one.

An intumescent is a substance which swells as a result of heat exposure, thus increasing in volume, and decreasing in density. Intumescents are typically used in passive fire protection and require listing and approval use and compliance in their installed configurations in order to comply with the law.

You can make your own with Astroputty:
http://www.astroflame.com/intumescent_putty.html

[836dstr]

Jack,

No, it's all home fab. Now usually 3 stages.

1. Conceptualize
2. Next day figure out the dimensions and materials needed
3. The next day figure out a different and simplier approach and start cutting metal (after a paper or cardboard pattern).

Finished cutting, welding, grinding, painting and installing today. Worked out great. Now some final adjustments to the linkage to verify full throttle opening and a throttle stop. As JD suggested in a PM, photos of everything for the Log Book to show the Inspectors all of the details.

Tom

[uniquefirestopper]

PLEASE DO NOT USE SILICONE SEAL OR GREAT STUFF INSULATION to seal your firewall.  It is flammable and VERY TOXIC when burning.

Visit www.uniquefirestop.com for solutions to sealing the automotive firewall.  Hoover over the PRODUCTS button and drop down to "automotive offerings".  This is a totally new concept - a firewall that WORKS.

Mike Sr.
Hobby Stock Racer...

Unique Fire Stop Products, Inc.
(251) 960-5018
shop@uniquefirestop.com