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[John R]

My exhaust pops and bangs on the overrun. Now i know what causes it; air being drawn into the pipe, I suspect mostly where it joins the head. I know how to cure it too; silicon sealant at least for a temporary fix. But what does it tell me about unburnt fuel going into the pipe? Is it running rich
'89 350, Goldie replica pipe, Mk 1 Concentric.

[PeteF]

Carburettors will always let a certain amount of unburnt fuel through.
That's one of the reasons why electronically controlled injectors are more efficient.

[Nettshubby]

I thought carbs ALWAYS let unburnt fuel through, it gets burnt after in the head!