rbowman wrote:
On 3/17/2015 6:20 AM, bob_villa wrote:
On Tuesday, March 17, 2015 at 7:11:55 AM UTC-5, TimR wrote:
When I was growing up car backfires were common. As a kid I had
friends who could make it happen at will. Now that the carburetor is
long gone, most younger folk have never
heard one. Fuel injection eliminated this, I think; could be
wrong. I never understood exactly what happens. Usually a car would
backfire when under heavy load, and the gas suddenly let up. So my
guess is the carburetor had a full charge with nowhere to go. But
what ignited it? Or, possibly the lack of air made an overly rich
mixture escape the
exhaust valves, and the explosion was in the manifold?

http://en.wikipedia.org/wiki/Back-fire


That article was pretty pedantic. What they refer to as backfire is
more popularly called 'carb farts' in the Harley world. Between a
primitive induction system, a wasted spark ignition, and EPA mandated
leanness, pre-FI bikes would tend to blow back through the
carburetor. That could be interesting if you were running without an
air filter.
What the OP and most people refer to as a backfire is what the article
calls an afterfire. There were a couple of hills going into town. I'd
cut the ignition on my '51 Chevy and pull the choke as I rolled down
in gear to make sure people knew I was coming.

We had a Mazda RX3 , if you let off the throttle coming down a hill , it
would come out with a VERY loud backfire . Something to do with one of the
two sets of points being off just a hair IIRC .
Anyway , we were coming down a not-too-steep hill into Brigham City Utah ,
and the traffic light at the bottom of the hill was out ... and there was a
Highway Patrol trooper directing traffic ... and I let off on the throttle
just right ... and that damn car blew just as we passed the trooper . When I
looked in my mirror , he was on the ground with his gun drawn and looking
for who shot at him . I still chuckle when I think about that . That
particular trooper was a real asshole or I wouldn't have done it .

--
Snag