Stuck Mix Adjustment Screw

Saloons
1

Wondering if anyone has any tips to help unstick my mix adjustment.

2x HD8s, rebuilt, front carb adjusts well, but rear seems to sometimes react to the adjustment, and sometimes not. Got my car back from the shop after a small tune up, and they adjusted the carbs too lean. Front carb took a 1/4 turn and now plugs are nice and brown/tan. Rear plugs still a bit white. I tried loosen and retightening the mix screw a few times but its hard to turn, much harder than the front carb which adjusts easily.

I’ve had this issue before, and a few times loosening and retightening eventually got the carb set right, so that’s what I’m trying, but wondering if theres something else I can do?

Thanks

2

Take the bell off and remove the piston/needle: If the adjustment now moves easily then your needle is rubbing on the jet tube - you need to re-center the jet.

More likely: The spring under the jet diaphragm is rusted away (Shouldn’t happen with a rebuilt carb if the diaphragms were replaced).