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SU carbs slow to back off.

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tomshobby

tomshobby

Yoda
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My 1974 Midget is looking good and running great after the extensive restoration. The only problem is that the throttle hangs up when I release the throttle when shifting or wanting to slow down.

The SU carbs are new and when checking the piston drop by hand the seem to be fine. Even if I accelerate by not opening the throttle much they seem fine. But when opening the throttle more between shifts or driving at even 30 mph or more the carbs are slow to back off. An example is that letting of the throttle when shifting from 3rd to 4th the engine rpm's race to the point where the throttle was opened and does not back off. If I tap the accelerator it will back off.

What do I need to look at?

Thanks, Tom
 
Sticky/binding cable is the first thing I would check. Keep in mind that sometimes they will seem fine with the bonnet up, but when closed could be causing some unusual pressure somewhere. Next check that linkage is not binding/rubbing somewhere. I don't think it's the carbs themselves.
 
Just to double check, do you have all three springs in place? One on each carb throttle linkage and the third on the cable linkage.
 
Hi Trevor,

I just got back from a test run to Peter C's shop. (World Wide Auto) It ran great and the carbs worked the way they should.
I am not sure it would be ready for a trip to Louisville but a few more miles and it might be.

Peter and Jane came out to look it over and the guys in the shop also came out to see it. They all liked it.

I do have the springs on and appreciate the reminder.
 
tomshobby said:
Gerard, it seemed to bind at the feral where the cable entered the foot well. A little lithium grease and a drop of Starrett measuring tool oil did the trick.
Thank you for the tip.
Tom
Click to expand...


:encouragement: nice when a fix turns out to be an easy one... thanks for the update... :cheers:
 
The springs do wear over time, and can snap...as I learned one time. That became quite the adventure.
 
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