Reply To: Alternative to a Amal 397 carb to fit howard 810cc engine.

[trusty-bloke]

I am not familiar with the 397 (so apologies), but from experience with other carbs a worn butterfly spindle can cause additional air leaking around the butterfly and upsetting the mixture such that the engine will rev and the tickover screw becomes redundant.
If you grasp the shaft and see what movement you have up/down/side/side ..etc..
That could a problem …

My experience is with 24T2 Zenith Carbs ..
Where the brass spindle wears more than the ally carb body …