[Grady Clay]

Scott,

I will speculate the mixture is already very rich even with the vacuum leak so replacing air with carb cleaner hydrocarbons simply makes it richer yet. Usually a small vacuum leak causes a lean condition (popping & such) and the carb cleaner brings the mixture closer to proper and the idle speeds up.

Why is it so rich? Did you adjust the mixture? Why was it apart? Was it adjusted prior to the disassembly to compensate for some condition?

If the idle changes at all – there is a vacuum leak.

I would systematically look at every connection and check every fastener. WD-40 is slightly less explosive to test with and may tend to seal a small leak for a few minutes. At the extreme, pull it all back apart.

I hope you are doing this outside on this beautiful Colorado day and have a helper standing by with a BIG fire extinguisher. We don’t want to see you, your nice SC or your great garage up in flames!

Best,
Grady