Red or Black Extenders for a QV?

There was a recent discussion about extenders, initially for a 328, with photos of the different versions:
328 Spark plug lead extensions???

In post #3 in that thread, I posted my information from researching extenders when I was installing the XDI system last winter - I'm pretty certain that a 308QV used the red 100mm extenders, part number 116613.

328 extenders are red, 107mm long. https://www.ferrariparts.co.uk/part/ferrari/126699
308 QV extenders were red, 100 mm long. https://www.ferrariparts.co.uk/part/ferrari/116613 or https://www.awitalian.com/product/spark-plug-extension-red-100-mm-long-fits-4-valve-euro-cars-only-116613.html/
308i extenders were black, 100mm long. https://www.awitalian.com/product/spark-plug-extension-black-100-mm-long-115647.html/.

 

I believe black or red supposedly designated the resistance of the extenders. I'm not sure that's always true now. For my 1985 QV I recently got red extenders from Superperformance to replace the black extenders which were in the car.. The resistance was consistent, but quite high (unfortunately I forget the specific number of ohms). The black extenders had very little resistance. Most of my other cars are from the 1960s with simple coil ignition so I was surprised at the high resistance and questioned David Feinberg at Sarasota Garage (they had rebuilt my Digipex units). He assured me that fairly high resistance was appropriate for the QV, since it had a positive effect on spark duration with the Digiplex. In any event, my QV seems to be running splendidly with the red Superperformance red high resistance extenders.

 

Black is 2 valve..red is 4 valve. Carries in to the flat 12s as well. Bb512.. black..tr red..

 

I'm planning on getting the wire set from Kingsborn
Their extenders come with the set

 

My 84 QV has the black ones and works great.

 

My understanding is that the difference between the red and black is that one has a resistor built-in and the other does not. The resistor is simply to reduce radio interference.

Virtually all spark plugs now have built-in resistors so it doesn't matter whether you use red or black. The spark is a bajillion volts (approximately), so the spark is not bothered by the resistance or by doubling the resistance.

I was not aware that there was a length difference between the two colors of extenders but if the length difference is only 7 mm, both lengths would probably fit fine.

Again, this is my understanding. I am no expert.

(For the record, I have black Kingsborne extenders in my '83 QV.)

 

Can't agree with that -- my original TR extenders, and every one I've bought (124792), has been black with zero resistance.
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As far as I can recall, we proved some time ago that color is no longer a 100% way to determine with resistance or zero resistance (as more suppliers have surfaced).

 

Personally have never seen black extenders on a TR..ever..

 

You can buy one from Maranello Concessionaires: https://www.ferrariparts.co.uk/part/ferrari/124792?id=52715

 

I think the answer to that is that you need some reasonable amount of impedance in the complete chain of wire + extender + spark plug to not overstress the output transistor of the Digiplex ECU that fires the coil primary -- i.e., if running stock wires with a stock non-resistor plug = use an extender with some resistance; if running the stock wires with a resistor spark plug = you could probably use a zero Ohm extender safely.

 

Since the NGK BPR6EIX is a resistor plug, I think you'd be OK with stock wires (which also have a non-zero resistance and a non-zero inductance) and a zero Ohm extender. Have you measured the resistance of your existing "black" extenders?

 

And the others?

(Usually the "burn thru" holes originate from the cut end of the wire that holds the spark plug end as that's where the charge density is highest -- yours, jumping of the smooth arc of the wire is a little unusual. Maybe just more related to that's where the old plastic material, where the spark jumped thru, had degraded the most -- and plastics have improved at lot in 40 years .)

 

Color is not important (nor determinant IMO). If you use a non-resistor spark plug = yes, use an extender with resistance.

 

You are putting too much emphasis on color IMO. It could be a zero resistance extender, but I'd prefer to see a resistance measurement (vs color). Also possible, that they have just messed things up as suppliers change, etc..

 

See post #8 in this prior thread:

https://www.ferrarichat.com/forum/threads/another-328-stumble-thread.212698

Color means nothing IMO.