alternative linkage connection for Walbro/Zama
 

I'm looking for some alternative connections for the throttle cable to lever that rotates the butterfly. I want to get rid of the slop in that linkage.
I added a shim from milk carton between the lever and the rotating part with the hole for control rod (it is like an E-Z connector with a cir-clip for securement) It helped but not enough. After some test stand time, 1) the retainer circ clip came off, 2) the set screw vibrated loose (did not have locktite on it)

I have looked (catalog only) at the balls links and the bolt-on swivel links as options.

2-56 bolts are too small for the existing hole. Would you make a bushing out of MarineTex (fill hole in lever and drilled to 2-56 body size?
What are the pros and cons of the options mention above? and please share any other idea / options.

alternative linkage connection for Walbro/Zama
 

Since this is my first attempt at a conversion, this may not be the best way, but I simply drilled a new (smaller) hole with a small burr for my dremel tool. Be carefull not to apply to much pressure while drilling, or you could damage something.

By the way, mine is a Zama carb.

Nosewheel steering arm!!
 

I like to use nosewheel steering arms....the have longer reach for better throttle resolution. You can get them to fit right over the throttle butterfly shaft after you trim the metal arm off....

Once you get it just right....grind a "flat" on the shaft so it doesn't vibrate loose and locktite it on....away you go...

This is the way BME does it, I think....

Get a equally long arm for your servo and you have very PRECISE throttle control..

High Flights@!
CrazyHerb

alternative linkage connection for Walbro/Zama
 

CrazyHerb
Give me an idea of the length your talking about . I understand the principle.


I visualize the flat, this steering arm must have a set screw to utilize the locktite?

What do you use for attachment of this arm to the control cable/rod?

The following really confuses me,, :confused: :confused:
I would think that where power/torque from the servo is not necessary, to get better resolution you should shorten the arm @ servo and use more 100% of the rotational range of the servo. Are you sure the length of the arm at the servo needs to be lengthened? :confused:

I have not checked the radio programming yet, I'm a builder at this point not a pilot, but it would seem that the expo thing might be a method of getting more more resolution of the carb butterfly. (desenitize the throttle?) if is is applicaple to the throttle chan..

I have digressed, to another subject again. My post was connectors to get rid of slop.

BYW , how did you get your handle? Just kidding, please take no offense! :D (Maybe I take things too literally! ;) )


strato911 I'm considering you new hole idea. It reduces the resolution somewhat, but more important is that I have all the holes drilled and control rods set for the old hole location of factory connector.

Pics worth a thousand words...
 

This should give you an idea...

http://www.shopatron.com/product/pro...d=DUB155/101.0

I didn't even think of my nickname in "that way" till two years into using it... it's mostly a reference to how I fly, and part of my last name.

A servo with equal arm length with the steering arm will give you 60 degrees of travel. Your right...a shorter arm on the servo would be more precise at the cost of total travel...

Hope that helps clarify a bit...

Good Luck!!

CrazyHerb

Pic on BME 44
 

Here's a pic of my old BME 44...get's the point across pretty well.

Enjoy!
CrazyHerb

alternative linkage connection for Walbro/Zama
 

CHerb,
Do you use the 'e-z' connector' type attachment as shown in the drawing or a ball or swivel link to make the actual connect to the throttle cable/rod?

You got me thinking some more on 'resolution' as well... Would you get more resolution with the following; At servo: shortest arm that would allow a large % of travel of servo shaft rotation ;
longest arm at butterfly which would reduce the cable /rod travel to the LEAST amount of butterfly shaft rotation ?

The existing butterfly shaft lever has about .65" of travel at the pin hole.

The engine will not shut down with the butterfly closed. The butterfly itself has a small hole in it. Is it necessary to solder that shut to totally cut air supply?

I have been known to get confused on concepts before, but I also accept changes to my thinking, once I find an explanation I can get thru my skull! :) My mind was a lot clearer before coming to Mx and discovering the national drink!

Ball Link best way to go...
 

The pic just happen to have a ez link...I would NOT use that on a gas motor....

I agree...ball link is the best. However I have used nylon clevises as well.

I think I'm going to solder my hole shut on the butterfly as well. Just for the sake of more control over airflow to the motor...and to be able to kill the motor with throttle.

One of the big things with the butterfly throttle is that it's not as LINEAR as the barrel carbs on glow engines...
Not as much change above half throttle.....it's like half throttle on the Tx is more like 3/4. A little mixing on my radio may help that...

High Flights!
CrazyHerb