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Throttle Cable Adjustment At Max?

rockitdoc

Well Known Member
Sponsor
EXP119 folks:
I got the throttle cable connected ok, but I am wondering if the fore and aft adjustment is correct. I put the throttle at 50% at the throttle body and the pulled the cable out from the panel 50%, connected it at the helm joint. This will work, but the fore and aft adjustment screw is at it's max travel. I would feel better if it were more centered. Does this seem correct?

Cable Throttle threads at max.jpg
 
Cables

Same as the others. Push it all the way in. Back it out 1/8".
Connect the servo end all the way at the stop. Should be plenty of cable to pull to ICO. If not, adjust the arm on the servo then the cable and joint.
 
If you mean the heim jointed end bearing, It is as far aft as possible and still too long. The photo isnt very good and probably doesnt show this like I had hoped.

If this is the case, then that makes sense (the cable is too long) - you have effectively made the cable as "long" as possible with the nuts on the bracket all the way aft.

Time to start over: loosen the jam nuts on the outer cable as far as they will go.

Run the throttle knob all the way forward and then back off 1/8 inch.

Hold the throttle arm on the servo to "full" and note the location of the outer sleeve in the bracket (the one you have pictured).

While still maintaining "full" travel on the throttle arm, adjust jam nuts to maintain this position, and tighten to final torque.

Run the throttle from idle to full travel and verify it hits the WOT stop on the servo BEFORE the knob hits the panel (should have a 1/8 inch gap)

Pull the throttle back to idle and verify it hits the idle speed stop screw on the servo BEFORE the knob runs out of travel.
 
Same as the others. Push it all the way in. Back it out 1/8".
Connect the servo end all the way at the stop. Should be plenty of cable to pull to ICO. If not, adjust the arm on the servo then the cable and joint.

I understand, but cable is still too long.

Here is mixture control at 1/8" from panel.

Mixture Control Out 1:8%22.jpg

Here is the cable adjuster on the engine as far back as it can go without running out of threads:

Mixture Cable to Servo Adjuster.jpg

And here is the cable at the servo. Still too long by about 1/4" even though the heim bearing end is threaded as far back on the rod as it can be.

Mixture Cable at Servo.jpg


I think I have to cut some of the threaded end off (maybe 1/2"), then cut some additional threads on the rod so the heim bearing end can be threaded further aft.

I don't see any other way. Weird that Van's wouldn't have provided a cable the correct length.

My throttle cable is also too long. It barely fits, but at the very end of the threads on the adjuster on the engine and with the heim all the way back on the threaded end. I would prefer the cables be in the center of the adjusters and the heim bearing turned out from the end maybe four threads or so.
 
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One problem at a time. Lets fix your throttle first. Clearly, you have made the cable "too long" by running the jam nuts all the way aft. That can be fixed in 30 seconds.
 
Throttle Done!

One problem at a time. Lets fix your throttle first. Clearly, you have made the cable "too long" by running the jam nuts all the way aft. That can be fixed in 30 seconds.

I readjusted the throttle as discussed. Pushed it fully forward, then pulled out 1/8". Pushed the lever on the servo fully forward and re-attached the heim bearing. This required that I move the adjuster jam nuts and nearly centers the adjuster in the bracket. This is now correct. When I move the throttle full forward the servo arm hits the stop. When I pull the throttle fully aft, the servo arm is fully aft, also. Full travel in both directions. Done. 30 secs.

But, this still leaves the mixture cable. I think it needs some threads added and the length of the threaded rod reduced about 1/2". This will get the adjuster with the jam nuts about centered.

Throttle at 1:8%22 Out.jpg

Throttle Adjuster .jpg

Throttle at Heim Full Forward.jpg
 
While it may be nice to have everything centered, as long as you have full thread engagement on the nuts, there is no security concern. Radically at the limits of adjustment is a cause to investigate, however. Is the mixture arm splined (clocked) correctly? One spline off can drive a noticable difference in the position of the heim pivot eye.

If other people are running this same exact setup without issues, then perhaps you have an outlier part - maybe the attach bracket or even the cable. If you ARE a "one off" configuration consider slotting or re drilling the holes on the bracket or adding an extension to the mixture arm. I did this on the RV-8 when I switched to vernier controls for mixture and found that I had far more travel (stroke) on the new cable than the short arm could use. The longer arm "consumed" most of the stroke and as a result, I had a finer, more precice control of my mixture. In your case, an extension on the arm would put the bolt hole right where you need it.
 
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Is the mixture arm splined (clocked) correctly? One spline off can drive a noticable difference in the position of the heim pivot eye.

That is what I was going to suggest. You can get your die and extend the threads, HOWEVER, you need to insure that that jam nut will not then limit retraction travel. WHile being centered may make you feel good, it is not necessary with full thread engagement. They make it long to provide flexibility; What is the point of that if it must be centered.
 
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Is the mixture arm splined (clocked) correctly? One spline off can drive a noticable difference in the position of the heim pivot eye.

Do you mean the arm on the servo? It is where Airflow Performance put it. But, if that were moved, I can see that the heim bearing could be made to fit. I will try that.
 
Mixture cable

<snip>

But, this still leaves the mixture cable. I think it needs some threads added and the length of the threaded rod reduced about 1/2". This will get the adjuster with the jam nuts about centered.

It looks like you have plenty of adjustment available on the cable nuts. Adjust the cable. The joint will move as well.
 
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