Plug wire CORE types
 

Recently I decided it was time to change my plug wires. I have no idea how long they have been on the car, and they are stiff from age and heat.

I purchased the Clewett wires from Pelican. The blurb here states that they are spiral core, but at the connectors all I see is a typical carbon fiber filament crimped in the connector.

By contrast, my old wires had real WIRE cores that were crimped in the connectors.


Which is considered a better choice?
I think RFI is no concern to me. The car is mostly used for track, and the radio is useless anyway.





Another thing I noticed is that the connections do not feed as positively locked in the distributor cap as the old wires did.

I probably need to give some more info:
78 SC, no computers controls, no DME, no Farnsworth demodulator. Just stock Bosch CDI.

Spiral core and carbon fiber filament is resistance wire. Same effect, reduced RFI.

Maybe others can chime in about RFI and the Bosch CD box. If no issues, I would use metal core plug wires.

I use SS core wires with a couple of Crane ign. boxes. I have no ignition issues.

Sherwood
'69

I searched before posting this thread and had found numerous threads about the different types of wires.

I have still been reading on the net and on Pelican, and it seems that the metal core is the best choice in race applications. But then I find a thread that says not to use with MSD. (Since MSD is basically just an aftermarket CDI, and Crane is pretty much a copy of the MSD, I don't understand why people say there would be a problem.)

Anyway, I'm putting my old wires back on after work today to see if I notice a difference. It will certainly be a slap to have spent $130 on wires that perform worse than the old ones on the car - but we'll see later today.

If that is the problem, then I will buy some new metal core wires and eBay my Clewetts.

I'm no pro, but there may be some info here that's useful.






http://forums.pelicanparts.com/porsche-911-technical-forum/238386-plug-heat-range-educate-me.html

http://forums.pelicanparts.com/porsche-911-technical-forum/285355-aftermarket-ignition-wires-installed-pia-next-time-back-oem.html

http://forums.pelicanparts.com/porsche-911-technical-forum/239262-ignition-wire-holders-they-really-needed.html

The connection may not be very obviouse to you, but the reason 911's have had so many fuel injection related problems is because of the problematic OEM copper core ignition wires.

My car is CIS, not EFI. No RFI issues.

Well, as I said I would do, I put the metal core wires back on. The car started easier and idles smoother. I'll email Clewett today.

I think I must be blind. Was there some issue besides the fact that they didn't feel quite as secure at the distributor? I keep looking for a problem but I can't find it. I'm asking because I'm thinking about changing my wires on my SC as well and would like to know if they are causing difficutlies.

Thanks.

Joe

You're not blind... I seem to have suffered some sort of brain trauma that kept me from fully explaining the issues.

When I switched wires, I found that the car was harder to start and has a rougher idle. This led me to start reading up on the different types of cores and posting this thread to try and find out if there was a functional difference between the types - ultimately to decide if I did a bad thing by switching to mag-core wires.

I want to be clear that I am not (yet) saying that something was wrong with the wires. I am only saying that there was a noticeable difference. I have been in contact with Richard Clewett about the issue.

Next week I will put the Clewetts back on the car and see if I can try a few things to improve the situation. If not, Richard has told me to send them in for a full shop test. And if there is something wrong with them, he will replace them.

I wish I knew more about the Bosch CDI system... I think a hotter spark is the solution. But I'm just guessing.

I use 8.5 Magnacores.

The plug boot isn't as idiot proof as the Beru's.

The distributor ends were tight so I installed the new set on an old cap for a couple of days and heated them w/a hair dryer to "break them in" a few times.


On a personal note, I don't like Beru's.

In a good operating system voltage delivered is dependent on voltage demanded by spark plugs. Plugs demand more voltage at WOT than at idle.

True, and increasing your gap will increase the voltage demand and result in a hotter spark. You just have to be sure that your coil can deliver. Placing too high of a demand will shorten the life of the components that were not designed to meet the increased demand.

That's why I wish I knew a little more about the design limits of the OEM system.

Next year I will be upgrading.... but that's next year.

piston power come from combustion power. combustion comes from ignition. The spark is god. You shape the spark. Increasing the gap can be more complicated than one.




Beru is a great wire when operating like new.



many different flavors to choose from. :D

The job of the ignition wires is to conduct an electric current to the sparkplug.

Best material would be gold, but that's a bit pricey

So next best at a reasonable price is copper core, either straight or spiral wound. The straight needs high resistance in the connectors to suppress RFI, spiral wound doesn't because it uses the orientation of the spiral to suppress RFI.

Lots prefer stainless steel, again straight or spiral wound because it resists corrosion better than Cu.

Other very good candidates are some of the more exotic alloys like monel metal, again spiral or staight. Again the draw here is resistance to corrosion

Bill... you're one of those guys on the board who seems to have a lot of experience. Do you have any idea why the Clewett wires would have given me hard start and rough idle? Should I have upgraded something else prior to switching wires?

Poor connection(s)?

Maybe. I'll give that extra scrutiny when I put them back on next week.