Hand Throttle conundrum

[Guest mccarthymf]

Hi Experts,

I've got a puzzler for you! My car, inherited from my Grand-dad, is a '28 Sport Runabout with a '31 motor.

When I got it about 15 years ago, the hand throttle lever on the steering wheel was cracked and eventually failed, and at the same time, the hand throttle linkage was missing altogether and apparently not used by my Grandfather. Using the Club's website, I found a replacement throttle lever made of "sterner stuff" than the original (Thanks to Jim Roberts) here: http://www.franklincar.org/forsale/parts.html

Installation of the new lever was straightforward and after reinstalling the steering wheel, my steering was relatively close to straight forward too! Not so the hand throttle linkage to carburetor.

Because my car is a "Hybrid" or "Hotrod" with a Side-draft motor not original to the car, diplomatically speaking: some compromises were made to make this combination work!

Check out these two pics:

There are two throttle valve levers connected to the common throttle valve shaft, one for the foot throttle side and one for the hand throttle side. The foot throttle linkage failed soon after I got the car and I replaced it with a long threaded rod and two yoke fasteners on either end, matching the bends in the old linkage. It seemed to work OK for the past 15 years or so. I lined up the two levers approximately 91 degrees apart using my poorly calibrated eye-ball but never bothered with the hand throttle side until now.

Meanwhile, with the install of the '31 motor and it's larger air cleaner, someone in the past decided to bend the original hand throttle arm 90 degrees so it would clear the cleaner! I've no idea how that lever connected to the throttle lever on the carb - it was all missing when I got the car. I've looked in the Parts Catalog #R-2982 to see what the original hand throttle connecting rod looked like - however; there's no way that rod would work in my car because of it's alterations.

I've tried extending the hand throttle lever's throw by attaching an 8" arm to the lever's two holes and re-orienting that lengthened lever to the "6 O'clock" position on the carb (sort of straight down) and was able to move the the lever too with a make-shift connecting rod of some heavy wire, but it also moved the accelerator and when I tried to use the floor pedal, it stuck open!

To ask a more succinct question: how the heck do I join the "non-standard" hand throttle lever/linkage to the carb? Does the common shaft mean that when using the usual foot accelerator pedal, that the hand throttle will always move too? Understand that this is a guy with a degree in History asking these questions!

Thanks for your time/patience/advice!

Semper Fidelis, Mike McC

[odyssey]

Hi Mike -

One solution: Install a rod end (restoration supply co - www.restorationstuff.com Or you local NAPA will have them in the Dorman line of hardware products)

into the bent link on top of the steering column. A rod end will get you pointed the right direction again. It will have a female threaded end, into which you can attach a rod.

In your photo, the carb link is pointing basically at the 5 O'clock position and you will need to change this to approximately the 8 O'clock positon. Then just a straight rod with a plain clevis (or another rod end) at the carb and you are good to go. Yes - the foot pedal will move when you open the hand throttle. This is normal. If the throttle then sticks, you have a geometry issue with the linkage. You can re-orient the arms on the throttle shaft to minimize any tendency to stick.

I hope that helps...

Tom

[Guest mccarthymf]

Tom,

As always - thanks for sharing your knowledge. I did have some input from Paul Fitz, as well, on this mash-up of a hand throttle.

I will re-orient the throttle valve lever as you both have suggested. Paul pointed out something that I didn't cover in my original post: When I reassembled the steering shaft and reattached the hand throttle cam and it's bits, I don't remember installing #2974, the friction spring. So I thought it needed a spring which you can see as the silver looking thing attached from bottom of carb to the bent throttle lower lever arm, #2972 in the 2nd pic.

That was a bad idea! Paul helped me understand that it's the action of lower lever on cam (with out the spring!) that allows the independent movement of foot pedal/hand throttle. I just didn't get that! I will reinstall one long spring, that he pointed out, provides tension for both returning the foot pedal to the "no gas" position (full aft) and keeps the hand throttle cam working too.

Marching orders for me:

1. Find a smallish diameter threaded rod and add some yoke fasteners on either end and connect the lower throttle lever to the carb throttle shaft lever that has been re-oriented to provide the mechanical "throw" to move properly.

2. Ensure that I "re-spring" by moving the "long spring" and finding a replacement "friction tension" spring and reinstall them.

3. Drive car!

4. Work on shortening run-on sentences.

Again, thanks for all that you do - which apparently doesn't include sleeping!

Semper Fidelis, Mike McC

[Guest mccarthymf]

Tom,

Thanks again for the great gouge: I moved the throttle shaft lever to 8 O'Clock, used the threaded rod and ball socket fasteners that I had on-hand, and used Paul Fitz's advice on removing the extra spring I had stuck on (the old friction spring was actually where it should have been).

The end result is that both the foot and hand throttle work just great though they are not pictures of authenticity, as shown here:

Again, thanks for all of your help, as you probably have figured out with me anyway, there will be more questions coming soon!

Semper Fidelis, Mike McC