MG Car Repair: mg midget, throttle shaft, vacuum leak

Question
hi,howard i have a 1500 mg midget 1980 which idles at 1500rpm if i tap the throttle it goes down to 900rpm.the rmp increase back to 1500rpm without touching the throttle?

Answer
Hi Daryll,
First disconnect the throttle cable and see if it still does it to isolate the problem between the cable and pedal from the carb itself. The Stromberg carb has a decell valve on the right side close to the throttle shaft that can be a cause of a fast idle. Also look at the choke assembly to see that it is not holding the throttle a little open. A worn throttle shaft can do it too as well as loose screws in the throttle butterfly to shaft. Even a vacuum leak can cause a fast and rough idle. When it is idling fast pinch off each vacuum hose one at a time to see if the idle drops.
Let me know,
Howard