MetalEd

I have a somewhat new pony carb (less than 6 months old) on my 170. I have been having a problem recently with the idle racing after the car gets really warm (after driving 20 minutes or so). The idle runs above 800-900 rpm. I also noticed a lot of carbon buildup on the exhaust manifold where the choke tube connects to it. So I thought my exhaust manifold had burned/rotted through and bought a new one. When I got the old one off, it is fine! The carbon/smoke is coming from the automatic choke and out onto the manifold!
What could this be? Could it just be my choke is set wrong and the "warm" idle is set too high (weather is getting warmer, so I originally installed the carb when it was much colder out.)
Is there something else I should be looking for?
Thanks for any advise!
Ed

2+2GT

You were right the first time. If you are getting carbon inside the choke tube, the manifold is trashed. The choke uses outside air, not exhaust. Carbon inside the choke tube means the manifold has failed. The replacement manifolds are pretty decent.

MetalEd

Should always go with your first instinct! Guess I just needed someone to confirm my suspicions. Thank you!
After taking the after-market choke tube off, I ran my hand along the exhaust manifold with the car running. I felt exhaust blowing right out were the choke tube connected. Even though I could not see the hole. Took the manifold off and found that a previous owner had drilled a 3/16" hole right through the manifold between the #1 and #2 exhaust ports to increase the heat to the choke tube. The choke tube, choke and even the vacuum duct in the heat riser (under the carb) is carbon fouled.
Got the new manifold on. tomorrow I will be cleaning out all the carbon from the choke. Looks like I got it before the heat did any damage to my vaporizer.
On a different note, just heard about pony carb's shutting down after the owner's death. It's a great loss to the Mustang community, these carbs are amazing as well as the instructional DVD that came with it (helped me find my problem this time!) They will be missed!
Again, thanks for your help
Ed!