At what point is plug wire arcing a problem ?

Deschodt · 04:48 PM

I've started hearing a tick tick tick noise on the right bank of my engine, it's 100% like the igniting spark of a gas stove, but much faster/shorter. Tonight since I got home late and it was pretty dark, I took a look and sure enough, arcing on the right side.

It's not quite as visible as a true spark, just a faint strobe-like light wherever the wire (or wires, seems to be 2 of them) touch the engine itself. I can grab those wires and not get any shock, but it's hard to isolate where the spark comes from exactly. Doesn't arc anymore if I move the wires away from resting on the engine and grounding...

Ok, so my plug wires are still soft and pliable, they "feel" new and are not all that old (3y tops, maybe 2 as I recall). The engine runs smooth as usual. Is some arcing par for the course ? Is any arcing a big no-no ?

If #2, what brand do you suggest I use instead ? I know porsche experimented with all sort of braided and other wires on the SCs - is there a consensus for better shielding, assuming I need it ? I've read some thread where brand new wires are still arcing for some people... Don't want to throw money at a non-problem if it's just static...

Edit: from reading more, it's more like a blue/white Aura than a highly visible spark, so I'm tempted to do nothing. Revisiting the topic in case someone found a better plug wire since !

911quest · 05:20 PM

Put it this way if they are arching and you all of sudden spring a fuel leak. I like the clewitt wire sets

aigel · aigel's Garage

I have always changed plug wires if I encountered such a condition - on any car.

George

Kevin Stewart · 12-02-2009, 05:25 PM

i would say any arc is NOT GOOD, Kevin

Deschodt · 12-02-2009, 05:30 PM

I hear you all... But I've been reading similar threads where people observed the same thing, threw good money at new wires (magnecor, factory, etc) and.... saw the same sparking with the new wires. I'm all for fixing this, but I don't have $$$ to fight windmills... If I do this, I want to do it once.

I'd like a seriously enthusiastic endorsement of a good brand before I do anything ;-) Preferably from someone who went from arcing to no-arcing ;-)

steely · 05:35 PM

If not a danger, it is at least a loss of power to the plug.
It takes 10 thousand volts to jump an inch in air, so just because the arcs are small, really doesn't diminish the problem 'cause they all sort of add up - it shows that there are cracks in the insulation - letting power out, and letting oxidation in. It results in a small but measurable load on the coil and loss of firepower. You can run with them, but over time you'll start skipping plugs as all the power goes to somewhere on your engine block. You should change them.
I got the blue ones from Magnecor.

Oops, I was writing when you posted. I went from arcing to no arcing and gained 40 hp. ;-)

for a poor mans' temp fix, with the engine off try wiping them down and taping with adhesive free self sealing silicon tape - it's temperature resistant. This is as a last resort only. Electricians tape will melt.

Deschodt · 12-02-2009, 05:37 PM

Quote:

Originally Posted by steely

I got the blue ones from Magnecor.

Oops, I was writing when you posted. I went from arcing to no arcing and gained 40 hp. ;-)

for a poor mans' temp fix, with the engine off try wiping them down and taping with adhesive free self sealing silicon tape - it's temperature resistant. This is as a last resort only. Electricians tape will melt.

40 hp ? I bet that was the magnecor sticker ;-)

Ok, so Magnecor:1 Clewett : 1 ;-) Me, still undecided on brand. But thanks, that helps, I'm gonna do it, just need to figure out which !

47silver · 47silver's Garage

they look great with the ss ground. they say porsche

Joe V · 12-02-2009, 05:45 PM

Hey Greg!

How are you?
Just wanted to share my experience. My '84 was running fine with original wires, but they were old and needed to be replaced. So I got a set of Clewett's from out host. Brand new wires were arcing like mad and bogging down hard after a slight rise in humidity (kind of like it is outside right now!). Turns out I had left one of the insulators off and they were grounding. Installed the insulator (like I should have in the first place) and the problem was gone. I can even drive it in the rain now!! Wow!

Take care!

Deschodt · 05:54 PM

Okie dokie... from our host - shoot me now !

- OEM-Style Ignition Wire Set, Stainless Steel Braided, 911 (1974-83) $198
- Genuine Porsche Ignition Wire Set, Shielded Cables - Left, 911 (1974-83) $254
- Magnecor Wire Set including coil wire, KV85 (red) 911 1965-83 $160
-Clewett Engineering High Performance Ignition Wires - BLACK, 911 (1970-83) $127.30
- Fyrebraid Ignition Wire Set, 911 (1965-83) $182.40
-Heavy Duty Ignition Wires, with Stainless Outer Braiding, 911 (1974-83) $297

Far from me to criticize our host for offering too many choices, but there you go, too many choices ;-) Normally I'd go "factory" but those have a history too on CIS cars. The Magnecor are advertised as "the best" on the site... So I'm tempted to follow Wayne's marketing here...

Any last minute advice before I whip out the credit card ?

Edit: joe, insulator ? The boot on the plug you mean ?

DanielDudley · 12-02-2009, 06:08 PM

Magnecore is what Steve W recomends, IIRC, and you do in fact need new wires. Whenever you get an arc there is a good chance that you will be losing spark on that cylinder, especially when under load.

911s run pretty strong on five cylinders, from what I hear...

Deschodt · 12-02-2009, 06:18 PM

Ok, that clinches it. What Steve W says (and Wayne recommends) goes !

Ordered $270 of stuff, Merry Xmas 911 !! Magnecors + clewett wire separators, for good measure a new distributor cap and rotor, and who doesn't need a few oil filters... oh and in these times of ethanol laced gasoline, a new fuel filter ! Right.... Shooting for free shipping again (and failed ;-)

Thanks guys, will report back in a week !

Joe V · 12-02-2009, 07:11 PM

Greg,

The 2 part cable separators that clamp around a strand of either 2 or 3 wires and in turn bolt onto a metal support bracket. Couldn't find them from our host, but it's part number 911 609 591 00 in PET.

Joe V · 12-02-2009, 07:12 PM

Greg,

The 2 part cable separators that clamp around a strand of either 2 or 3 wires and in turn bolt onto a metal support bracket. Couldn't find them from our host, but it's part number 911 609 591 00 in PET.

rcaradimos · 12-05-2009, 07:40 AM

Is this what your looking for? Center of pic, I have 2 two wire and 3 three wire OEM separators for sale.

rcaradimos · 12-05-2009, 07:51 AM

Carrera Spark Plug Wires?

snbush67 · snbush67's Garage

Not sure what rotor you are using but if you are using anything aftermarket to send a spark you might consider using a rotor without the diode/resistor as they tend to fry, better to get a solid core rotor.

Best. Shane

brads911sc · brads911sc's Garage

Especially if that is a CIS car...

Quote:

Originally Posted by Kevin Stewart

i would say any arc is NOT GOOD, Kevin

brads911sc · brads911sc's Garage

Magnacore or OEM.

Quote:

Originally Posted by Deschodt

I've started hearing a tick tick tick noise on the right bank of my engine, it's 100% like the igniting spark of a gas stove, but much faster/shorter. Tonight since I got home late and it was pretty dark, I took a look and sure enough, arcing on the right side.

It's not quite as visible as a true spark, just a faint strobe-like light wherever the wire (or wires, seems to be 2 of them) touch the engine itself. I can grab those wires and not get any shock, but it's hard to isolate where the spark comes from exactly. Doesn't arc anymore if I move the wires away from resting on the engine and grounding...

Ok, so my plug wires are still soft and pliable, they "feel" new and are not all that old (3y tops, maybe 2 as I recall). The engine runs smooth as usual. Is some arcing par for the course ? Is any arcing a big no-no ?

If #2, what brand do you suggest I use instead ? I know porsche experimented with all sort of braided and other wires on the SCs - is there a consensus for better shielding, assuming I need it ? I've read some thread where brand new wires are still arcing for some people... Don't want to throw money at a non-problem if it's just static...

Edit: from reading more, it's more like a blue/white Aura than a highly visible spark, so I'm tempted to do nothing. Revisiting the topic in case someone found a better plug wire since !

Hugh R · 12-05-2009, 06:38 PM

Not positive, but my experience on cars in general is that if it's arcing, the plug isn't firing because the spark when somewhere else. You only get one discharge when it fires. The plug, or to ground somewhere else. Think about it, why would you have two distributors for twin plug motors, otherwise you'd just split the one wire to the two plugs.