Need Your Experience and Advice

[rn2fine]

On my 350 equipped 72 I am having two problems (listed below). I am looking for advice from those with experience on how to deal with the problems.

1) Starting approximately 1 week ago the engine began to diesel (continue running after I turned it off) big time. It is a 350 with 20,000 miles, Edelbrock heads, Edelbrock carb, and HEI. Runs great, engine temp is great (180), its not overheating, running premium gas, and timing is per specs. I also have an O2 sensor and gauge and mixture is good. Running Bosch +4 platinum plugs and have since engine was new. I called a friend and he said it may be a stuck float in the carb that is leaking fuel into the manifold after shut down. Any thoughts?

2) WHen I turn my air conditioning on I, and after it is on for about 5 minutes, I begin to smell something burning in the cab, coming from the dash area. There is a large red wire that comes out from the back of the ignition swith and I felt it when I smelled something burning. It was really hot. Too hot to touch for more than a second. When the AC is not running the wire is cool. AC blower fan is running great with no signs of problems. A friend of mine states that I should replace ignition switch. Any thoughts?

Thanks