Bates cautions that it's critical to place the hole in the firewall correctly. Depending on your setup, the throttle linkage will move up and down a little as the accelerator is pressed down, so you want to make sure the hole is sized large enough that the rod won't make contact with the side of the hole and create a potential sticking point.
But, holes in the firewall are potentially dangerous places for fire to move from the engine compartment to the driver's compartment. A rubber grommet is the standard hole plug when it comes to firewalls in racing, but it's not a particularly good solution in this instance because it can also make for a sticky throttle. The best solution Bates has found is to make a Kevlar(R) fabric boot to seal the hole and protect the driver.
At the Carb
The opposite end of the throttle rod connects both to the carburetor throttle control plate and the mechanism for the spring return. A two-piece bushing cradles the spring clip so the bolt connecting the throttle rod to the carburetor throttle control plate can be properly tightened down without cinching the spring clip. "To keep the clip rotating freely, some people will try only threading in the bolt part way and Loctite it in or something," Bates explains. "They always manage to back out when you do that. It's better to use some type of bushing to keep the clip rotating freely after the bolt is tightened down all the way."
Finally, once everything is in place, Bates calibrates the throttle linkage so that a secondary throttle stop on the gas pedal engages at the same time as the primary stop on the carburetor. The carburetor throttle stop comes from the engine builder calibrated to keep the butterflies from opening beyond 100 percent open throttle, so it isn't difficult to match to that. The redundant throttle stop on the gas pedal is just for an added bit of safety, Bates says.
After every race the throttle linkage is inspected along with every other part of the car. The maintenance required is to clean the pieces and occasionally put a little bit of lubricant on the heim joints. Bates says he has never had a linkage fail on its own. Just what every racer wants: simple and effective. CT
 Johnny Benson's Valvoline...  Johnny Benson's Valvoline Pontiac uses a through-the-firewall gas pedal,which makes for a very simple connection to the carburetor. |
 Ken Schrader prefers a different...  Ken Schrader prefers a different gas pedal design for his M&Ms Pontiac,which is contained completely on the driver's side of the firewall. Thismeans a larger hole must be made in the firewall for the throttlelinkage to pass through. The MB2 team solved this opening problem bycreating a Kevlar(R) fabric boot. |
 If you aren't currently using...  If you aren't currently using a throttle stop on your carburetor, thinkabout something like this. It's simple and just about bulletproof. Thethrottle control plate butts up against a bolt that is threaded in orout to reach the correct height. An adjuster nut (and some Loctite)holds everything down tight. |