Throttle linkage adjustment

nkcarizona

nkcarizona

Member
Finally getting my '29 roadster on the road. Have rebuilt engine, Tillotson carb. The throttle does not set down on the idle screw when the hand throttle is all the way up and the foot feed is off. As a result, the engine idles too fast.

If I bent the throttle link arm on the passenger side backward I could solve the problem, but I'm leery of breaking the arm. Does anyone have experience with this? A slightly longer connecting rod from the arm to the carb would do the trick, but I don't think they are available.

I would appreciate any suggestions.
 
I have the same problem. I've bent the throttle arm some but I don't think that's the proper fix. Maybe someone knows how to correct this problem that many of us have had.
 
I was wondering this also... why are some throttle arms bent and others not? are there different sizes? there can't be any setup differences from car to car so why do some ppl have them bent and others not..
 
Do you have the right one? Over time I have seen them bent wrong!
 

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If you re refering to the part that points downward from the accelerator crossover, they are bent for several reasons. 1. damage from lifting the cab or body off the frame. 2, damage from installing or uninstalling the crossover. 3. damage fron installing a muffler incorrectly. 4 intentionally bent to compensate for a short (or too long) carburetor connecting link. The links come in several length depending on whether made in Mexico, China, Argentina or USA. We can only hope the USA made one is correct.

They can be straightened and the curve at the ball end corrected by removing the crossover and using hammer and dolly (or anvil) gently hammering until the worse of the kinks are out. Dont use heat or it will soften the metal and then REALLY easily bent. Work it cold. I use a correct one for a guide and to whats right or bent wrong. I then clamp the straight section in a vice and using a box end wrench work on the curve til I get it right.

Reinstall the crossover then use tha same box end wrench fine tune the curve til it fits the carburetor linkage.

The linkage on the driver side that connects crossover to your foot is usuall bent badly and has to be rebent to get the arc at the pedal right.

clear as mississippi mud, right. Ken
 
You could also bend the throttle arm on the carburetor. The butterfly in the carburetor can bind if it is not properly lined up in the throttle shaft inside the carb. You could disconnect the linkage at the carb and check for bind and free movement. You may need to remove the carb, loosen the butterfly screws and adjust the butterfly. Its pretty simple one thing can be bent or adjusted to allow for another. You just have to analize the problem. If one thing doesn't work try another. The parts can be bent or rebent as necessary. Its really pretty simple.
 
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The forged end is easily bent while cold. The foot pedal end is harder to bend, but I've seen them bent also, so they don't follow the hole in the wood as they are pressed down.
 
As Purdy Swoft says, the throttle arms on the carburetor can be bent to help correct the problem. They have often been bent out of shape at some previous time.
 
in addition to all the possibilities already mentioned here, all of which I have encountered on one car or another: The entire crossover bracket gets bent up when the engine is removed or installed without removing the crossover first. It catches the cab and gets pulled back on engine removal, then someone whacks it back into place with a hammer and it ends up too close to the engine block, or it gets smashed into the firewall during engine installation. In either case, the bends hold the carburetor throttle open a bit. The first thing I check is the lengths of the rods, since there are so many bad repros, as well as V8 rods used. Once that has been corrected, careful analysis of the linkage to determine all the damaged points is undertaken.
 
It is the forged end that I need to bend. I am concerned about breaking it, but it sounds like you think that won't be a problem.
 
You probably couldn't break it if you tried. You'd have to bend it back and forth numerous times. However, before you bend it have you disconnected the rod from the steering column to the throttle linkage to make sure it's long enough? As Pat said, that's often the culprit.
 
This is an older thread, but you can learn from my mistake. I jacked up my engine to replace the rubber pads on my float-a-motor motor mounts and bent the throttle linkage. If I had removed the 2 bolts to begin with it would have prevented this issue.
 
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