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Likely cause of throttle sticking open

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I got the new TR6 the road yesterday. Whoa - can you say TORQUE? Holy cow!

Anyway - her throttle is sticking open. Not the the actual linkage from the pedal but the spring loaded Lever. She moves freely when the engine isn't running but when the engine is running she tends to get stuck open at around 4000 RPM.

Only the left one sticks.

Any ideas?

[https://www.mossmotors.com/Shop/ViewProducts.aspx?PlateIndexID=32750#54]

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I don't quite understand I guess, because usually the throttles are tied together by the linkage between the butterflies. You do need to have the springs on the throttle shafts set up sufficiently tight to beat the suction effect that will tend to want to open the throttle when the engine is running - I am suggesting that maybe it isn't sticking/hanging up so much as being sucked open? Pete
 
Sorry if I wasn't clear.

The linkage between the carbs is working. What happens is when the gas pedal is depressed the throttle gets stuck open at around 4000 RPM. I don't think it is the mechanical linkage from the gas pedal to the carb.

It almost seems like the spring on the left carb is too tight and as a result the throttle shaft isn't returning to idle. Would vacuum from the carb keep it stuck open?
 
You can do a couple of things real quick to see what really is happening with the carbs. First off, do you have a good throttle return spring on your cross shaft that attaches to your throttle pedal? There is a spring right where the cross shaft lever attaches to the throttle arm. I ended up using a much stronger spring that I scrounged from NAPA. Next, try undoing the two carbs from each other by loosening the little spring clips that fit over the carb throttle shafts. You can probably work one carb with the gas pedal and one with you hand (need a helper here), then reverse to make the other one work off the pedal. Even without the trottle mechanism, you can gun the engine with your finger and watch the carb return springs do their thing. Gotta be a little cooardinated here. Each carb should idle down without help. That way you can isolate one area at a time.
Be careful doing this, not a good idea to run the engine off one carb for long.
Just some thoughts.


Bill
 
Another possiblity is that your linkage is binding a little.
Make sure the control rod(the vertical link between the carbs) is not cocked off at an angle. It should be fairly vertical. Also, make sure your joints are lubricated.
 
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