Carb tuning question

[jjenloe]

I have what I believe to be a 77-79 Federal Aisan carby on my ‘82. Due to some dieseling after shut off, I am trying to adjust the carb. When I turn the mixture screw, it makes no noticable difference in idle. So that doesnt seem right.
I’ve checked for vacum leaks and timing. The only thing I see that might be an issue is that thE fuel level in the sight glass is slightly over the half mark.
Any viable/relevant suggestions?

 

[charliemeyer007]

Dieseling to me is caused by carbon build up in the combustion chamber. How old are your plugs and wires? How do drive it, lugging it around all the time, short trips - take it out and open it for a while to burn the gunk out.

When was the last time the carb was cleaned? Use some fuel system cleaner might be a good option. Running rich leads to carbon build up. Adjusting the mixture should have some affect on a clean working carb.

 

[jjenloe]

Dieseling to me is caused by carbon build up in the combustion chamber. How old are your plugs and wires? How do drive it, lugging it around all the time, short trips - take it out and open it for a while to burn the gunk out.

When was the last time the carb was cleaned? Use some fuel system cleaner might be a good option. Running rich leads to carbon build up. Adjusting the mixture should have some affect on a clean working carb.

I replaced plugs, wires, cap, rotor 3 years ago. I drive it about 5000 miles a year, so not that much. However, it is mostly highway speed, 55-60 mph. I also use ethenol free fuel with 93 octane.
It may or may not be realated, but I doubt that would affect the mixture screw not making any changes when fully turned or out. It could be a separate issue. I also rebuilt the carb 3 years ago. At that time, it worked fine and was able to be tuned.

 

[jjenloe]

Also this

 

[charliemeyer007]

Fuel evaporites when not used often, and leaves shellac in it place. I suspect the carb is gummed up again. Try some spray can carb cleaner into the mixture hole and any other port you can get to easily. On a dark night open the hood and start it up - look for dancing fire off the wires.

 

[jjenloe]

Fuel evaporites when not used often, and leaves shellac in it place. I suspect the carb is gummed up again. Try some spray can carb cleaner into the mixture hole and any other port you can get to easily. On a dark night open the hood and start it up - look for dancing fire off the wires.

Thats a great point. I got some Berrymans to put in the tank and to pour down the carb.