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Backfire thru exhaust at idle
- Thread starter Griff
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Doubtful or you'd be smoking it during starting...
Griff
Well-Known Member
Lol, thanks for understanding. A man's got to know his limitations, right
You need to do as Dads Bee said or else we are wasting air.
Griff
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ok, i'm getting ready to post a few pics...give me a bit
Griff
Well-Known Member
For sure, he's batting 1000 in my book, won't be able to do that until tomorrow night.
That photo is not a 69 quarter and that ground is not good,
Griff
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Really, what year quarter is it?
All I can say is the side markers are no held in like a 69 would be, Not right to me.
Griff
Well-Known Member
There is no side marker lens, that is my tool box.
Looks like a 69 to me.
Well my beer goggles told me different last night. [lol]
I think you just landed the key - plugs! Had a really stout built 440 some years back that would pop at idle when the plugs got fouled. Ran fine with some rpms but popped like crazy at idle.
BeepBeepRR
Well-Known Member
LMAO.. this is funny. On Friday I took the headers off the roadrunner and replaced them with HP manifolds and TTI down pipes. After I installed them and installed new plugs as well. I noticed a popping every now and then when at idle. I was like WTF? Well, upon looking further into it I noticed that I had 2 and 4 swapped on the plug wires. DERP... Swapped them around and its running great now. Double check your firing order.
18436572
Driver side front to back
1357
Passenger side front to back...
2468
Counter clockwise rotation
18436572
Driver side front to back
1357
Passenger side front to back...
2468
Counter clockwise rotation
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Late to the party as usual....
Your headers may be the cause of
the backfire issue. 2" header tubes
are rarely used in hp ratings less
than 500 on a 440.
Too large a diameter and the inertia of the incoming gas will be insufficient to scavenge the cylinder of exhaust gas. (unspent fuel in
the header).
You may be pushing unspent exhaust
gasses towards a hot header (now
red hot) with them acting like
a spark plug. Your backfire/popping
may be occurring in the header tube.
I'm thinking you need to increase
your exhaust flow rate. This problem
is magnified if your headers aren't
tuned as flow rates can vary.
Had the same problem on a newly
rebuilt 440 and had a set of headers
built custom, tuned, and 1-7/8 ID.
No backfire after warm up.
I know....just what you need...
something else to check out.
Your headers may be the cause of
the backfire issue. 2" header tubes
are rarely used in hp ratings less
than 500 on a 440.
Too large a diameter and the inertia of the incoming gas will be insufficient to scavenge the cylinder of exhaust gas. (unspent fuel in
the header).
You may be pushing unspent exhaust
gasses towards a hot header (now
red hot) with them acting like
a spark plug. Your backfire/popping
may be occurring in the header tube.
I'm thinking you need to increase
your exhaust flow rate. This problem
is magnified if your headers aren't
tuned as flow rates can vary.
Had the same problem on a newly
rebuilt 440 and had a set of headers
built custom, tuned, and 1-7/8 ID.
No backfire after warm up.
I know....just what you need...
something else to check out.
Last edited:
Griff
Well-Known Member
Thanks for the advise 1stMP. Yes, the 2" headers are kind of a pain. They are so close to plugs, wires, power steering, and mini starter. I may change out to a little smaller in future. I'm running heat wraps on everything. But, combined with the 3" exhaust straight back with glass packs dumping at axle, it does sound good too me and probably not change this summer. Maybe over winter I might. As for the popping, it has not come back once I changed to a power master alternator with the built in regulator. It seems Dadsby was correct in that a single wire 1969 alternator would not work correctly with a post 70 voltage regulator. Have not had a problem since at idle.
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