"Feel" of gas pedal

[jhelgesen]

When I had the CIS system on my car, the gas pedal had a nice smooth and long throw, good resistance to pedal pressure. Now that I have switched to webers, the pedal has a short throw with very little feedback. I tried adding a second spring where the throttle rod comes into the engine compartment. It added some of the throw distance back at the pedal, but it is still not very smooth and is almost too stiff.

Does anyone have suggestions for adjusting the "feel" of the gas pedal?

[azasadny]

John,
I agree that the pedal feels different between CIS and Webers, but I really like that way the pedal feels with Webers much more! Has your pedal cluster been rebuilt in the recent past? Perhaps you could rebuild it and use the brass bushings and get the feel you're looking for? I'm going to rebuild my pedal cluster this winter.

[RWebb]

some of the bell cranks have different length 'throws' on them

[jhelgesen]

Originally Posted by RWebb

some of the bell cranks have different length 'throws' on them

Hadn't thought of that, I'll compare the cis hardware to whats there now, see if I can change the geometry to what I had.

[JP911]

When I switched from CIS to PMOs I was amazed at how sensitive the gas pedal was. In fact it was undersprung as the pedal would not return to rest when I rolled to a stop, leading to a high idle. An extra spring in the linkage helped. I did not however experience any change in the "throw" of the pedal.

[jpnovak]

The CIS tranny bell crank is about 1 cm longer than a corresponding weber version. The angle between the two arms is also much wider. This multiplies the movement of the arm and thus the more stiff, on/off feel of the carbs.

For a better feel, find an early bell crank and then adjust your linkages to fit it. Its time consuming. You could also just get used to it. I got used to it for a year and then finally went in and fixed it. I also think the tunnel rod is longer on the CIS version compared with the earlier.

[Zeke]

Originally Posted by jhelgesen

Hadn't thought of that, I'll compare the cis hardware to whats there now, see if I can change the geometry to what I had.

Shouldn't be too difficult. Seems like all would be the same except the length of the pivot point on the carb body. Needs to be longer if there's room. If not, can you modify the bell crank on the tranny?

[Peter Bull]

Originally Posted by jhelgesen

Does anyone have suggestions for adjusting the "feel" of the gas pedal?

Carefully increasing the friction in the pedal mount or one of the linkages will do the trick. That will increase the effort needed to push the pedal, thus making it easier to control. This will require a little tweaking and maybe getting a stronger return spring.

Just to emphasize; I am not talking about large amounts of friction, just a little bit to slightly increase the resistance in the pedal.

/Peter

[jhelgesen]

Got a chance to play with the linkage a little last night. Found an extra 1/2" of throw in the back end when I disconnected the throttle rod from the bell crank. Wondering if it changed when I changed manifolds (the 46's came with short manifolds vs my tall ones).

Had to trim a 1/4" off the end of the rod to get the ball cup to screw down any further. Next I'll get under the car and see if I can tighten the throttle rod at the tranny.

Measured the length of the bell crank and its the same as the old cis arm.

Then I'll see if I can play with the strength of the spring I added.

[jhelgesen]

Reinstalled the linkage this weekend with the shorter rod. With the slop out, the pedal felt pretty smooth. Don't have a pedal stop on my car yet as I have home made aluminum floor boards, but think I need to add one, still have a lot of space to floor at WOT.

[JP911]

Be careful driving without a throttle stop as you can easily overstress the linkage. I tore the rubber bumper in the linkage after the tunnel (common failure point) when my throttle stop was too low. The other, albeit rare, possibility is that the throttle plates with go past vertical and get stuck open.

[jhelgesen]

Thanks Jon, I plan on adding something for a stop this week before I head to Roebling this weekend.