<VV> back firing

[HallGrenn at aol.com]

In a message dated 12/5/2008 8:22:48 AM Eastern Standard Time,  
kovacsmj at sbcglobal.net writes:

What you  have is called an after fire. It is caused by excessive gasoline 
(vapors)  that are not burnt in the cylinders and is then ignited by the fire  
coming out of the exhaust when you back off the throttle. It usually goes bang  
inside the muffler.

Why is (I guess) too rich a mixture or one of  the carbs is putting too much 
fuel in when it should be closed? What does  Grant say?

Anybody else have an idea?
MIKE KOVACS  



SMOG (A.I.R. pump cars) had the same problem for a different reason.   If the 
diverter valve didn't work properly the fresh air pumped by the A.I.R.  pump 
would cause a bad case of backfire when you backed off the throttle.
 
Bob Hall
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