myfairlady Posted February 20, 2016 Report Share Posted February 20, 2016 My 1972 521 is now backfiring out of the blue , what do you think is causing it? 1 Quote Link to comment
Charlie69 Posted February 20, 2016 Report Share Posted February 20, 2016 Has any mechanical work been done recently. Mileage, back firing on deceleration, through the carb? Need more information to help you. 2 Quote Link to comment
datzenmike Posted February 20, 2016 Report Share Posted February 20, 2016 Out the carb can be an intake valve that does not seal when closed. Cylinder fires and it gets out and back into the intake. This can be from no valve lash (too tight) to a bad face/seat seal (worn or pitted) a bent stem (not closing) damaged/broken. Excessively lean can also backfire out the carb. Out the exhaust is usually an interruption of the ignition long enough for the un-burnt gas and air to be pumped into the exhaust pipe. When the ignition resumes, the un-burnt gas explodes in the pipe. This can be extremely dramatic. I have split mufflers before from this. Usually a loose wire on the primary side of the ignition system is the cause. Points in need of replacement can also do this. 4 Quote Link to comment
Charlie69 Posted May 23, 2018 Report Share Posted May 23, 2018 Double post Lack of sleep. Sorry Mikey! LOL 1 Quote Link to comment
datzenmike Posted May 23, 2018 Report Share Posted May 23, 2018 Holy necro post 2 Quote Link to comment
pwrcat4000 Posted July 3, 2018 Report Share Posted July 3, 2018 Since it's been backfiring a couple years now I say "if it's not backfiring it's not running" don't even worry about it LOL 1 Quote Link to comment
DanielC Posted July 3, 2018 Report Share Posted July 3, 2018 This is a long shot now, but would be more likely 30 years ago. Does the truck still have the original L-16 with the air injection into the exhaust ports? 1 Quote Link to comment
mainer311 Posted July 3, 2018 Report Share Posted July 3, 2018 Backfire on decel is almost always an air leak. Burbling on hard decel is fairly normal. My roadster does it and it sounds awesome. 1 Quote Link to comment
datzenmike Posted July 4, 2018 Report Share Posted July 4, 2018 OP last here 29 months ago so......... 1 Quote Link to comment
pwrcat4000 Posted July 4, 2018 Report Share Posted July 4, 2018 What Mike is saying is, guys this is a dead post! The person is no longer even here probably. The original post was made 2 years ago. Just some fun at Charli69's expense. Happy 4th of July 521'ers 1 Quote Link to comment
Charlie69 Posted July 4, 2018 Report Share Posted July 4, 2018 It's OK guys I do not sleep much so have fun with it! The funny thing is I would have never noticed! LOL 1 Quote Link to comment
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