[Mike Taylor 3601]

What Billy said,did you hear engine on dyno ?Has carb had fuel sitting in it since dyno?
Had BBC that was working on one time,idling sounded like carb or valve lash too tight,idled sound like was on 6cyl. all that was good,with idling tried to get feeler gauge in between rocker/valve would'nt go,shut off lash would check right, long story short tore down found lobes just strarting to go.

If have temp gun may shoot ex and find if one cyl. colder than others,no vac @ idle I would guess you are getting comp. back in intake,ethier valves being held open some reason ,bad lobes? bent valves?

Mike Taylor 3601