Learning_Curve

I'm getting close to firing my Lt1 swap for the first time after not touching the project for years. Finally got around to installing a throttle cable. I was excited to be one step closer to having a driving vehicle untill I discovered the throttle plate is only opening about half way. The gas pedal is about even with the brake and clutch before pressing, so the only way i see getting any more travel is to mod it so that it sits higher. Other option would be to shorten the rod below the pivot, lenghten the top part, and mount it lower on the firewall. that would change the ratio and give me more throttle pull vs pedal input. Ive been looking at aftermarket pedals, but they seem to have even less favorable ratio.

I know there have been many tpi/lt1/ls1 swaps on this site, but I dont rmember this ever coming up as an issue. Am I missing something obvious?
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Patro46

You bring up a valid point. Here is what I ran into, and recently.

I did an LS swap in my 74. I later added an LSA Supercharger. The throttle body cam on an LS is pretty much fixed-it is what it is. The foot pedal on our C3's doesn't offer enough "throw" in factory form to open the throttle blade all the way. In factory form with an LS and a Lokar cable, when I buried the gas HP Tuners was only showing 80.4% of the throttle blade opening. This was preventing the blower from building much boost.

I pulled the foot throttle put it in a vice and created more "throw" by bending the rod. Doing this and adjusting the cable as tight as possible gave me 98.2%, still not WOT of 100%, so I'm looking into another solution as well

Richard454

Put up a pic of the throttle-

The throttle cable is going to move so much...and sounds to me like it will take a bunch of work- to get the pedal and cable to cooperate!!!

At the point where the throttle cable connects might be the easiest place to "increase" the travel- by just changing the connections higher and/or lower.

I was able to do this w/ some parts from Speedway Motors and the junkyard-

Learning_Curve

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Richard454

That's a tough one-

How much movement do you lack?

Here's a couple of quick thoughts-

Add a pulley for the throttle cable- artist rendition!! Will increase the throttle plate movement w/ same amount of cable pull distance.





Change the fulcrum point of the throttle pedal- could be as simple as moving the throttle connection at the top a small amount-

Learning_Curve

Before I go too crazy, I'm going start with bending the gas pedal. It ended up only being a little higher than the other pedals (which are adjusted low anyway, I wanted as much leg room as possible). I hate giving up the leg room, but I don't want to end up with a stiff gas pedal that is only good as an "off/on" switch.

Now if I can just get the damn thing started...

Luce

You can deepen the groove the cable rides in on the throttle body, shortening the throw required.

I've had to completely design from scratch 3 throttles on hotrods I've built. One ting that is nice is if you can make the pull progressive so the first 1/2 of the pedal throw only opens throttle 1/4. then the last 1/2 opens it to full. Makes it much more drivable. I did it on the 8 stack and it's very manageable without getting the bucking horse thing in first and second gear. But this requires a bellcrank.

rebel542

I bent my 79 TPI just above the pivot point giving it more throw.

Danish Shark

Bent gas pedal rod is very common.
Simply bend it back into position and you have restored the original travel.

7T1vette

Modifying the geometry of the crank on the throttle linkage is a better method than just bending the accel pedal. You just need to extend the distance from the pivot point so that the throttle will move farther for the amount of pedal movement.

You've driven for years with cars that have about the same amount of pedal travel. It will feel weird to have a pedal stick up that far.