We have been trying to find the source of backfiring & eliminate it on a
friend's BN7 (twin carb). Every time he shifts it back fires one time, very
loud. It sounds like a rifle shot. I am not talking about the normal rumbling
during deceleration. The car has recently been fully restored. The engine,
distributor & carbs were professionally rebuilt. We have double checked the
timing & carb adjustments. We cannot find any exhaust system leaks. If there
are any they are very small. The tail pipes exit in front of the left rear
wheel. The muffler has some damage, it was partially crushed when trying to
unload the car from a trailer when it got hung up on the trailer bed to ramp
angle. However, I could not see, feel or hear any exhaust leak in the muffler
or pipes. I have read previous posts on this subject & they always seem to say
that the cause is running lean or rich or exhaust leaks. I don't think we have
any of these issues. Can you suggest any tests we could do to isolate the
cause of the backfiring? Has anyone experienced this type of backfiring &
eliminated it? How?
Gary Hodson
|