I have used Seafoam to clear carbon-take a well warmed up engine, put a can of Seafoam down the carb or thru a vacuum line, adding the last little bit quick enough to stall engine. Let sit 15-20 mins, then restart & rev engine, I like to drive them. they will smoke like Hades for a while, but it will stop. his is nearly identical to the "top end cleaning" done by GM dealers. brian
