Gary, had a similar problem with a fellow AHSTC members car. Backfired LOUD!
Drove three hours each way to help him out. Went through everything and it
only made it somewhat better. He previously had Pertonix ignition installed
and when we swapped out the dist with and conventional points one, the problem
went away.
Message: 9
Date: Sun, 13 Mar 2011 10:18:38 -0400
From: warthodson@aol.com
Subject: [Healeys] backfiring
To: healeys@autox.team.net
Message-ID: <8CDAFA0AE46DB73-1938-34C25@Webmail-d116.sysops.aol.com>
Content-Type: text/plain; charset="us-ascii"
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
The Millers
"British Car Nuts"
1957 Austin Healey 100-6 BN4 35299
1959 Austin Healey 100-6 BN4 77219
1964 MGB 40841
1960 Austin Healey Bugeye Sprite AN5 34351
"Always drive them, but remember each drive in an antique car is a test
drive."
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