backfire after engine is off?
#1
domokun!
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backfire after engine is off?
well, i drove today for a short distance in the 7 and when i shut the engine off today i heard a backfire almost a second later.
any suggestions of what might case this?
and can anyone help me tune my holley carb w/o the muffler rich/lean device?
thanks.
any suggestions of what might case this?
and can anyone help me tune my holley carb w/o the muffler rich/lean device?
thanks.
#6
Lives on the Forum
Mine will usually let off a fart after shutting it down. Always been that way since the RB exhaust went on. Pretty sure there are no leaks in my system. Sounds more like a poof than a bang though...
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#8
FB+FC=F-ME
Pretty typical on a carbed engine,especially with an aftermarket exhaust.
When you turn off the key,the sparkplugs stop firing,but since the carb is mechanical,it still lets out fuel,until the engine stops turning.That fuel cant ignite,since the sparkplugs arent firing,so it collects in the exhaust and will spontaneously ignite if the temps are high enough.With EFI engines,turning off the key stops the injectors and the sparkplugs,so you dont get that after-burning effect.
My old carbed engines did it with the stock carb and with the Yaw carb.Somethimes a bang,sometimes a poof.It depends on the fuel/oxygen ratios present each time it happens.......ever fired a potato cannon? Depending on how much/little fuel you spray into the breech,you can get a "poot",or an ear shattering "BANG".....even though its the same device.
I only noticed it with the RB exhaust system,but I wouldnt doubt that it still happens on stock cars too.Your just less likely to hear it through cats and the well baffled stock muffler.
When you turn off the key,the sparkplugs stop firing,but since the carb is mechanical,it still lets out fuel,until the engine stops turning.That fuel cant ignite,since the sparkplugs arent firing,so it collects in the exhaust and will spontaneously ignite if the temps are high enough.With EFI engines,turning off the key stops the injectors and the sparkplugs,so you dont get that after-burning effect.
My old carbed engines did it with the stock carb and with the Yaw carb.Somethimes a bang,sometimes a poof.It depends on the fuel/oxygen ratios present each time it happens.......ever fired a potato cannon? Depending on how much/little fuel you spray into the breech,you can get a "poot",or an ear shattering "BANG".....even though its the same device.
I only noticed it with the RB exhaust system,but I wouldnt doubt that it still happens on stock cars too.Your just less likely to hear it through cats and the well baffled stock muffler.
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