Backfire

[tonyjh63]

Ok, so I dropped my boat off at my mechanic's to have a remanufactured carb installed...
He just called and said that he it had a hard time cranking up, and when it did, it backfired and blew out the intake gaskets. How does a backfire occur, specially that big of one? Ugh!
Btw, it's a 4.3 Mercruiser.

 

[Rick Stephens]

Usually timing causes backfire, or an out of time cam, but I can see a flooded intake manifold having the potential. 4.3L intakes don't have much torque applied to the bolts.

More I hear about rebuilt carbs less I'm comfortable being around em.