What causes back-firing?
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Supreme Member
Joined: Mar 2001
Posts: 2,262
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From: Renton, WA
Car: 1985 Camaro, 1986 Trans Am
Engine: 5.0L carbed and 5.0L TPI
Transmission: TH700R4
Axle/Gears: 3.23 and 3.27 posi
What causes back-firing?
My '68 Camaro back fires when very once in a while and its pissing me off. What causes backfires?
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'82 Camaro SC - totalled
'80 Camaro SC - sold
'83 Camaro Z28 - sold
'85 Camaro Z28 - sold
'94 Camaro SC - stolen
'68 Camaro - for sale
'91 Camaro RS - my new baby
------------------
'82 Camaro SC - totalled
'80 Camaro SC - sold
'83 Camaro Z28 - sold
'85 Camaro Z28 - sold
'94 Camaro SC - stolen
'68 Camaro - for sale
'91 Camaro RS - my new baby
Supreme Member
Joined: Jul 1999
Posts: 5,183
Likes: 42
From: Oakdale, Ca
Car: 89 IrocZ
Engine: L98-ish
Transmission: 700R4
Backfires out the exhaust (after fire) indicate unburnt fuel, reigniting in the hot muffler/pipes.
Causes are many, retarded, incorrect timing (valve or ignition) rich mixture (usually only afterfires on acceleration though)
back fire through the intake is caused by incorrect mixture too, usually lean, and or incorrect valve and ignition timing as well.
Keep in mind that incorrect timing doesn't necissarily mean you base timing is off, but that the cylinder could be firing from a crossed plug wire, cross arcing from wires, etc.
Header/exhaust leaks are good for after fires as well, drawing in air to ignite the hot exhaust gases in the pipes.
There's probably a several other things, but generally fuel and ignition are the first things to look at.
Causes are many, retarded, incorrect timing (valve or ignition) rich mixture (usually only afterfires on acceleration though)
back fire through the intake is caused by incorrect mixture too, usually lean, and or incorrect valve and ignition timing as well.
Keep in mind that incorrect timing doesn't necissarily mean you base timing is off, but that the cylinder could be firing from a crossed plug wire, cross arcing from wires, etc.
Header/exhaust leaks are good for after fires as well, drawing in air to ignite the hot exhaust gases in the pipes.
There's probably a several other things, but generally fuel and ignition are the first things to look at.
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