Fast Idle Problems

[Pentastar Pete]

1970 340. I have a Demon 650 carb. Engine and carb about 5 years old. 
Took the car out of winter storage and noticed that the idle sometimes would jump to 1500 rpm and stay there for a while then come down. All the linkages are fine.
Choke is set. Nothing hanging up. I also changed the carb gaskets. No vac. Leaks.
I also noticed that the left side headers are getting hotter then normal. All the plastic wire loom holders melted. I had then since day one and never had a problem.
The engine also sounds alittle different.
Could timing be an issue?  I'm at a loss... 

Thanks
Pete

[MEK-Dangerfield]

A timing problem would definitely cause the headers to be hotter than normal... I'm not sure about the rest. I know others have had trouble with Demon carbs.  Sorry I'm no help.   

[Pentastar Pete]

How about a stretched timing chain?? or could I have jumped time??  would that cause an idle to raise like that?

[72cudamaan]

Sounds to me like you have a idle circuit plugged, somehow causing the engine to run too lean.

[BIGSHCLUNK]

I really doubt its a timing chain issue..... 

[Pentastar Pete]

Andy,   How would I check that idle circuit??  Someone else said that for some reason, it sounded like the carb leaned it self out.

[72cudamaan]

I'm no carb expert by any means. But the fact that you are running super hot is definitely a condition of running lean. Maybe your float level is low. I guess I was looking towards  the idle circuit because only 1 side seems affected. Hopefully someone better with carbs can chime in and help. Also as a side note, could you have a sticky vac advance or sticky weights. I wonder if this might be causing an advanced timing condition that would raise nthe rpm's ?

[Pentastar Pete]

Andy,

Thanks very much for the time and input it puts me in the right direction..