Getting full IDF linkage travel

[ward00]

Wondering if anyone has had an issue with getting full throttle opening on their IDFs.

On my car with the gas pedal all the way to the floor, the best I can do is about 85% opening of the throttle plates.

I updated my linkage (which was mounted on the cam tower at the rear) to one that is made my Allen Lofland (its mounted centrally on the cam tower).

The Lofland linkage makes it easier to mount a turlteback on the IDF.

However, with either linkage full gas pedal movement does not translate to full throttle plate opening, which translates to less max HP.

BTW, why ant we upload images on this forum without going through hell? If anything, this issue will cause the death of this site?

[Nut124]

I'm working on an IDF conversion. I previously had dual DCNFs with a home made linkage.

For the IDFs, I measured the stroke, or travel of my throttle cable and then fabricated a linkage lever arm for the IDFs thta has the same travel from 0-90 as the pedal.

Does your setup have a reversal arm? If so, you could modify it to add travel to the carb end.

[ward00]

I understand the lever arm solution. With the old linkage I was able to flip it upside down and install a new ball long farther out on the arm to increase the lever effect, but even then, although travel improved, it still resulted in only about 85% throttle opening. I could increase it even more with a cludged longer lever arm, but I want to install a turtleback, and cant do it with the old system, however modified.

With my new linkage, movement in the gas pedal is linked directly to the the intercarb linkage by the cable and without any lever arm, thus movement of the gas pedal translates directly to the same amount of movement of the linkage, which also results in 85% max opening of throttle butterflies. The only solution I can think of is to bend the gas pedal up so that it allows for a longer range of travel at the pedal, which will allow a longer range of motion at the intercarb linkage.

I wonder how many people install dual IDF and don't realize that they may have the same issue I had/have. After all, it takes tow people to be able to see if the throttles open fully.

[Nut124]

How is the carb linkage oriented in your setup?

Mine is still off the car. I fabbed a custom lever arm from weber pieces for the carb shaft. It sits between the carbs and the ball for cable connection is under the shaft. I will mount the carb cable horizontal, pulling to left, on the underside of the manifold. The cable bracket will be held in place by the carb studs, below the manifold carb flange.

[ward00]

A picture would take the place of a thousand words, but alas its not to be on this site without needless work. The new linkage that I am using to be able to mount the turtleback is a customized length of throttle cable/sheath that attaches at one end to/through the firewall. The sheath is about two feet long and forms a loop along the midpoint of the height of the carbs and that attaches at its other end to a bracket that is mounted to the hole that is more or less in the middle of the cam housing. The end of the sheath is held fixed by the bracket and a spring applies an expansion force to keep the cable and the throttle in an initially closed position. The issue is that that the gas pedal bottoms out before the throttle fully opens. Since there are no lever arms with my set up, all I think I can do is bend the gas pedal up so that there is a larger range of travel of the pedal and hence the throttle butterflys.

[rebar1111]

I read a lot about dual IDF's and their linkage.

I have dual IDF"s with the turtleback mounted on 2L 79 with a large stock bubble hood. Using stock 28/32 carb linkage, I have no issues with installation or function. A slight grinding on the hood reinforcement for turtleback clearance and it was fine.

I suggest considering a complete 79 linkage transfer. I am not sure of the details of earlier year cable controls, but the 79 installation was a breeze to install.