Backfiring
Thread Starter
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MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
Backfiring
Hi all,
On my '73 400, after I start the motor and punch the gas with the engine cold, it first starts revving like it should but then it bogs down and backfires. It only does this when it's cold. After a few minutes it is back to normal.
My timing is around 10 degrees BTDC. Could the timing be the problem, or is my choke too lean or too rich? The choke is at 3-rich, perhaps the choke pull-down is too wide?
Thanks
On my '73 400, after I start the motor and punch the gas with the engine cold, it first starts revving like it should but then it bogs down and backfires. It only does this when it's cold. After a few minutes it is back to normal.
My timing is around 10 degrees BTDC. Could the timing be the problem, or is my choke too lean or too rich? The choke is at 3-rich, perhaps the choke pull-down is too wide?
Thanks
Senior User
Joined: Jan 2003
Posts: 176
Likes: 0
From: Addison,Texas
You could peg the choke plate full open and start it cold and see what happens.
You've got a cold miss and then some air is getting in from somewhere and you've got the backfire. Without any other info to go on, the straight-forward thing to do would be to do a cold compression test, followed by a hot one to make sure you haven't got a bad cylinder.
ash
['Sounds annoying.']
You've got a cold miss and then some air is getting in from somewhere and you've got the backfire. Without any other info to go on, the straight-forward thing to do would be to do a cold compression test, followed by a hot one to make sure you haven't got a bad cylinder.
ash
['Sounds annoying.']
Postmaster
Joined: Aug 2001
Posts: 4,270
Likes: 5
From: Delaware
Sounds rich to me. The plugs are loading up and gas is passing into the exhaust manifold. Then as Ash said you have air and fuel and heat, then it backfires.
I would lean the choke setting and try it.
I would lean the choke setting and try it.
