Car is running great, but recently it has developed a backfire on the left side (none from the right). Letting off big time leads to a big pop, while normal slow downs lead to mutiple smaller pops. It didn't use to do this. What do I check for, fouled plug, bad plug wire, or what. I'm clueless...
Have hydraulic lifters so I don't think a valve is sticking open.
Cobra Make, Engine: NAF 289 FIA, 347 stroker with Weber 48's, building a '48 Anglia gasser, driving a '55 Chevy resto-rod
Posts: 3,119
Not Ranked
I've experienced the same thing, replaced my exhaust header gaskets(they are not leaking) and the header to exhaust pipe gaskets. Things were fine for awhile, then the backfire started again, turned out that it was from the header/pipe fitting, again, same side, blew out the gasket, replaced it once again.
It is slowly starting to leak again, sort of pops, especially when backing down. I'm sure it'll start the "k-pow" again in a short time.
I wish I had an answer but I've tried darn near every header gasket and combination, maybe my old pipes/connectors are just getting worn out.
__________________
"Breathe in... Breathe out... then move on with life. Lifes too short to sweat the small stuff"
I had the same thing happen - and it was caused by the tyre!
What happened was the tyre went soft, I understeered out of a sweeper at the race track, and hit the sidepipe on the ripple strip! Of course - it did make the manifold leak, but the tyre sounded like a better story.
Dave, Sounds like you might have a too lean condition.
I can not remember if you have a carb or FI, but what you can do is sweeten the mixture at the idle screws and see if the problem goes away.
It is common if you use the engine as a braking assistant and the engine revs are high enough to need more fule to sustain them. Yet your foot is completely off the pedal.
Simple way to check may be to give a little pedal as you slow down and see if the popping stops.
Just a thought. Are you still drinking with the cows?
__________________
I'm a writer, feed the artist and buy a book.
I recently experienced this "LEAN"condition of popping or backfiring out of the left side pipe on deceleration and was given three places to look.
Intake manifold to cylinder head gasket
Header to cylinder head gasket
Sidepipe to header flange gasket
Well im my case the intake manifold gasket had disintergrated and moved out of shape to cause a vacuum leak at #5 cylinder. Replaced the intake gaskets and that was it.
Cobra Make, Engine: E-M / Power Performance / 521 stroker / Holley HP EFI
Posts: 1,931
Not Ranked
Hello Cowtown Cobra,
All of my various exhaust orifices have leaked at one time or another causing backfires
If it's the collector, the best seal is this soft copper one (or equivalent from other vendors). If it's good enough for AA fuel dragsters, I reasoned, it's good enough for me
There are other brands of locking header bolts available.
And don't forget that there's still Permatex Red high temp sealant to try.
Does all this work? I don't know
It depends on vibration, temp, thickness of flanges, load on the joints (well all those pipes and stuff do sort of hang off the header flanges, don't they?) and intangibles.
It's a good idea to check the bolts pretty frequently too.
If you find a better way, please let the rest of us know
Regards,
Tom
__________________
Wells's law of engine size: If it matters what gear you're in, the engine's too small!
Dave, Sounds like you might have a too lean condition.
I can not remember if you have a carb or FI, but what you can do is sweeten the mixture at the idle screws and see if the problem goes away.
It is common if you use the engine as a braking assistant and the engine revs are high enough to need more fule to sustain them. Yet your foot is completely off the pedal.
Simple way to check may be to give a little pedal as you slow down and see if the popping stops.
Just a thought. Are you still drinking with the cows?
Yah, I had to put the horses on the wagon, so the cows are all I've got left
I was out there the other day and saw all the photos in their albumn. It really turned out nice. Saw several bodies straight out of the mold. Lookin real good, great lines.
Now if I could only convince she-who-must-be-obeyed....
I had the same thing early this year. After the car set for the winter I broke it out and noticed a backfire on the right side only. I had a loose plug wire. I wish they were all that easy....Check the simple stuff first.
__________________
SPF 1618
460, 552hp
+ Pro Shot Fogger system
(250hp shot)
802hp total
titanium\black stripes
Cobra Make, Engine: Contemporary CCX 34010, FE 428
Posts: 6
Not Ranked
Thanks all -- cured!
Aha! I just changed my CCX's valve covers and got the one sided backfire. I was positive I had screwed up the valves somehow. But it was just a plug wire I accidentally pulled... thanks Spoony for the quick fix!!!!
I wasnt so lucky and was getting a popping on accelration. Turned to be a bad spark plug. The ceramic was cracked. So dont always assume spark plug wires, spark plugs get damaged also.
Quote:
Originally Posted by Indy
Aha! I just changed my CCX's valve covers and got the one sided backfire. I was positive I had screwed up the valves somehow. But it was just a plug wire I accidentally pulled... thanks Spoony for the quick fix!!!!
Backfire on one side
Linear Mode
