2 problems...
Thread Starter
Drifting
Joined: Jun 2007
Posts: 1,404
Likes: 1
From: Ansonia/NYC CT
2 problems...
...possibly related. Problem one is, under hard acceleration, it backfires when shifting up to the next gear, the moment I push the cluth pedal in. Seems to only do it at higher rpms.
So...I thought maybe my firing order might have gotten crossed somewhere when I changed the sparks plugs, so I popped the hood and chased wires, but they are in the correct firing order. HOWEVER, with the engine running, I was poking around, and saw that the spark plug for cylender 6 was arching. A tiny spark was hitting the header tube, and it was coming right from the boot!
So I checked the others, specially the ones that sit closer to the header tubes, but no arching. Furthermore, 6 was arching to a rythm...no arching for a few secs, then 6-7 consecutive archs, then no archs, etc etc.
The wires are MSD street fire wires. The boots for 3,4,5, & 6 sit very close to the block hugger headers. Even if stock, though, they would sit just as close to the old rams horns. Plus, 3,4 and 5 seem to have no issue with this. Are these two issues related, and what can I do to fix them?
So...I thought maybe my firing order might have gotten crossed somewhere when I changed the sparks plugs, so I popped the hood and chased wires, but they are in the correct firing order. HOWEVER, with the engine running, I was poking around, and saw that the spark plug for cylender 6 was arching. A tiny spark was hitting the header tube, and it was coming right from the boot!
So I checked the others, specially the ones that sit closer to the header tubes, but no arching. Furthermore, 6 was arching to a rythm...no arching for a few secs, then 6-7 consecutive archs, then no archs, etc etc.The wires are MSD street fire wires. The boots for 3,4,5, & 6 sit very close to the block hugger headers. Even if stock, though, they would sit just as close to the old rams horns. Plus, 3,4 and 5 seem to have no issue with this. Are these two issues related, and what can I do to fix them?
Melting Slicks
Joined: Jul 2010
Posts: 2,503
Likes: 33
From: McGrady NC
St. Jude Donor '15-'16
Bad wires. Usually when a wire starts arcing it creates a path of carbon that is difficult to repair. If a little bit of dielectric grease around the inside edge of the boot does not fix it then the wires and possibly the plugs need to be replaced. That could cause the backfire issue, but so could a lean fuel mix. Check for vacuum leaks, too. Hoses and the carb base gasket are good places to look. High mileage or abused engines create new sources of problems, but start simple.
Melting Slicks
Joined: Jul 2010
Posts: 2,503
Likes: 33
From: McGrady NC
St. Jude Donor '15-'16
Are they arcing from the base of the boot where the wire goes in or the open end around the plug? Arcing at the base means you take them back. Arcing around the plug end means the plug may have enough dirt\grease\whatever that the current has a path out to the header tube.
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Burning Brakes
Joined: Aug 2005
Posts: 1,164
Likes: 1
From: Europe, France
Maybe your spark plug boots are too close from the headers so they burn quickly.
You could try shorty spark plugs like the ones ACCEL make. It would give extra clearance ( about 7 or 8 mm more ) and could save the life of your new wire set.
Arcing would also be reduced to a minimum with the extra distance to cross..
You could try shorty spark plugs like the ones ACCEL make. It would give extra clearance ( about 7 or 8 mm more ) and could save the life of your new wire set.
Arcing would also be reduced to a minimum with the extra distance to cross..
Instructor
Joined: May 2010
Posts: 172
Likes: 3
From: Hesperia California
Arcing wires ? backfire
If you find out that it is not the wires or plugs, here is a thought are you running the original smog pump ? if so rev the engine up and let off does the car steal backfire or at cruse and back off gas does it backfire, if so decel valve on the smog pump is bad and or the vacuum line from the decel valve is hooked up to the wrong vacuum source. 2 cents, I use to have many customers come in with this problem after someone worked on there cars, its a very easy mistake to make not putting the vacuum hoses back in the proper places. But this will also cause backfiring and usually it is big time.This may also help others that have backfiring issues and its not the usual carb, wires, timing, ex-ct. firstvett69.
Burning Brakes
Joined: Aug 2005
Posts: 1,164
Likes: 1
From: Europe, France
IMHO, I think new spark plug boots AND shorty plugs is the way to go.
As long as it's still arcing, you won't solve your backfires issue.
You probably have some cylinders that sometimes misfires.
I'm using ACCEL 0576S ( S= Shorty ), but I'm not sure that your engine needs the same heat range, so first check equivalence with the ones you have...
As long as it's still arcing, you won't solve your backfires issue.
You probably have some cylinders that sometimes misfires.
I'm using ACCEL 0576S ( S= Shorty ), but I'm not sure that your engine needs the same heat range, so first check equivalence with the ones you have...
Last edited by 73StreetRace; Sep 2, 2010 at 05:47 AM.
Race Director
Joined: May 2003
Posts: 10,956
Likes: 409
From: California
Do you have headers? are thy ceramic coated if you do? I was burning MSD wire boot after boot after boot because of the heat, and that I would get arcing...changed to shorty plugs and ceramic headers... problem went away...
Burning Brakes
Joined: Aug 2005
Posts: 1,164
Likes: 1
From: Europe, France
Even if ceramic headers upgrade isn't really what I would call a cheap fix...
Race Director
Joined: May 2003
Posts: 10,956
Likes: 409
From: California
sometimes the Cheep way turns into the long and expensive way...
good luck... p:-)
Thread Starter
Drifting
Joined: Jun 2007
Posts: 1,404
Likes: 1
From: Ansonia/NYC CT
They are shorty headers, but they are not ceramic. Before going that rout, I'll just get header wrap for them. It's just odd that this is only happening on the number 6 cylinder, and no others, seeing as number 5 on the other side is exactly the same.
Thanks for the input, guys.
Thanks for the input, guys.