A carb that sits below the exhaust manifold and heat transfer area just might be susceptible to leakage past some loose exhaust valve guides. That normally goes down the exhaust system with no evidence.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!