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Steve Sampson

Well Known Member
I started hooking up the throttle today. First I had to make this bracket to stand the cable off from the bulkhead as you can see here.
http://gikonfuse.blogspot.com/2008/02/throttle-cable.html#links

But I have a problem. With the other end of the cable in the middle of the 3 holes on the Marvel throttle lever I am not 100% sure that I am getting the full range of travel. It just kisses the low speed stop,but I am not 100% confident the butterfly is fully aligned with the air flow when wide open. I will probably take the airbox off and look.

My question though. What is normal? Do VANS normally propose you use the middle hole or the inner one resulting in the shortest lever arm? Anyone know?
 
I have previously thought about this problem.

What about bolting a small plate on the throttle arm; spanning between the second and third holes? Then drill a new hole in the plate. The bolted on plate is essentially a tab in which to locate the most ideal cable attach spot. This would put the cable attachment between the two holes. The clock position of the throttle arm can be adjusted slightly to account for the addition of the plate. This is what I am going to try/do.

Does this make sense? Thoughts? Faults?
 
I wish I were at home to confirm, but I am pretty sure my carb only has one hole. I also seem to recall that the full travel of the cables does not quite allow full stop-to-stop travel on the mixture or throttle. It is short by just a wee bit, but still...? It has nothing whatsoever to do with the quadrant travel or position, but rather the internal stops in the cable itself. I posted on here a while back about it but didn't get a definitive response, so I decided to put it off til later.
 
I spent alot of time setting up the throttle and mixture. it is possible to get stop to stop travel using the middle hole, but everything has to be perfect to make it work, even after spending what seemed like hours on it i still wasn't convinced that i was hitting the stops so i filed a small amount off the washers that space the quadrant just so i could see an air gap at each end of the travel.
 
Steve,

There are a few different lever arms for the carb, so be careful hooking it up. One person's middle hole may not be in the same place as another. (No dirty comments guys and gals.)

You want to adjust it so the levers on the carb (Mixture and throttle) hit their stops before the lever on your quadrant does. On my throttle quadrant, I have about an 1/8" gap on the throttle quadrant when the throttle and mixture are full forward and then again when they are full aft.
 
Throttle lever arm/cable.

Brian Vickers said:
I have previously thought about this problem.

What about bolting a small plate on the throttle arm; spanning between the second and third holes?

Does this make sense? Thoughts? Faults?
Click to expand...

Brian - I messed about with it some more today and now think I have the 100% range of the quadrant matched to the 100% range of the throttle. I like dcleco's idea of smaller washers (Thanks!). What I plan to do is make some very short bits of that ally tubing that just fits over a 3/16 bolt to replace the washers to act as a spacer. It is smaller dia. than a washer. I think then I will have a bit of a space at each end on the quadrant when the carb is at full range.

Your idea of a plate bolted on will undoubtedly work, however on something so important I would really rather do it the standard way, though I can not begin to see what would go wrong. Also, as the arm shortens you loose sensitivity. (Crucial when your hanging on the prop crawling into my short strip!) Brian, lastly thank you very much for your kind words about my butterfly!

SteveZ and N941WR, the link below is the carb lever arm I was talking about, but there may well be others. My Supercub, built in '68 is very similar.
http://gikonfwf.blogspot.com/2008/02/throttle-and-mixture-linkage.html#links
 
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