resistor or non-resistor plugs?

Asked this question yesterday but it was buried in a long post so you may have just skipped over it...

What are the advantages and disadvantages (if any) of using resistor spark plugs? This is a purely conventional breaker-point ignition system (single point Prestolite distributor on a '62 Stude V-8, if you really must know) stock coil stock everything except for modern silicone

7mm suppression wires and a vintage Sun tach. Would like to keep my radio quiet, but not at the expense of performance.

Does it change things any if I'm planning to convert to a Pertronix unit, CD box, or Chrysler electronic ignition box in the future?

I'm trying to figure out what the "right" plug is for this engine. Learning in the process how much there is to know about spark plugs (that I don't know.)

thanks

nate

Reply to
Nathan Nagel
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Actually, no.

Some applications call for resistor plugs, others call for non-resistor plugs. There is no benefit to second-guessing the manufacturer's specification in this regard, unless the rest of the secondary side of the ignition has been fairly radically altered as well. There is no single little statement like the one you made that is accurate across all (or even most) applications.

DS

Reply to
Daniel J. Stern

Less RFI and EMI, slower spark plug gap growth.

"Modern suppression wires": Not good enough information. The car would've originally come with suppression wires. What'd you use? Carbon-string wires? Spiral-core wires?

I'm quoting Autolite because it's the best catalogue and I have good results with their plugs.

216 is the "book plug" for a '62 289. It has a standard tip. Optional in this exact heat range slot is 4316, which also has a standard tip but has a tapered centre electrode -- this helps avoid tip fouling and give surer starts, and half a notch hotter is 437, which has a projected tip that does a much, much better job of keeping itself clean than the standard tip.

None of these has a resistor -- resistor plugs are not available from Autolite (nor, I suspect, from anyone else) in the configuration your engine takes. Me, I'd start with a set of 437s.

DS

Reply to
Daniel J. Stern

Suppression wires have the resistance built in, thus no need for resistor plugs.

Reply to
Bill Kapaun

Geez, I'd have to ask the guy that made them for me. (yes, there's a guy in the Stude club whose business is custom wires. He mostly sells to engine builders but also does them for Stude and Packard engines.) I believe they are carbon and not spiral core but I don't have a set here at the house to look at.

Oddly enough their web site recommends a 437 for all V8s except for 57-8 Golden Hawk and truck (which makes sense, they used a plug a step colder) but I took that with a grain of salt because I know the standard V8 and the R-series engines should use different reach plugs according to my (Studebaker) books. What I'd REALLY like is a Bosch equivalent because that's what my local cheapass auto parts place sells and I've had good luck with Bosch... I know they have to make a plug for me, I just don't know what it's called :) (that is actually how I got on this little project, someone recommended a Bosch part number to me and I suspect that it is something that someone had kicking around in their garage, it fit, and their car didn't run like complete ass afterwards.) Anyway stock plug is a Champion H14Y but I haven't been able to find those. Not sure if those are still current or not.

The question about resistor still stands though... I've also got a '56 Golden Hawk (packard engine) as well and the plugs that are currently recommended by the 56J web site *are* resistor... curious why? (original plugs were Champion N-8-67B whatever the hell that means. That's certainly not a current part number...)

I really need to find some old books. that's all there is to it...

thanks

nate

PS - once I get all these old books collected, I'm going to retire and open my OWN parts store. Probably lose my ass too but oh well.

Reply to
Nathan Nagel

Your brush is a bit too broad for the paint job, Andrew.

Reply to
Larry Smith

yes, but it's the right color. What the auto makers are trying to do is to get a burst of energy that goes through the are, and does not have some bounce back .

Andrew

Larry Smith wrote:

Reply to
Andrew Paule

Secondary current is microamps (for those brave enough to try to measure it), the primary drivers are capable of handling at least 6-8 amps in a typical system, (the EI stuff Nate's describing)

8-10 amps in a DIS system. Why would such a small secondary current cause damage?

Haven't seen a coil pack (solid state or otherwise) that has an output driver, is this something new?

(note: some coil on plug and coil near plug systems now have the primary output drivers integral, but COP and CNP systems do not -use- coil "packs.")

Hell, I've been using resistor plugs in a non-resistor application for over 13 years (I suspect Steve Lacker& Dan Stern amongst other in this froup has also) without a single controller failure that could be attributable to the use of resistor plugs in a non-resistor application.

Reply to
Neil Nelson

Greatest gap theory.

The plug gap and the dielectric value of that gap are what determines the output voltage of the ignition secondary. Odds are that a resistor plug and resistor wires would appear totally invisible WRT demands on the coil secondary (assuming a 12 volt primary and a coil capable of at least 24KV secondary output, IOWs, standard stuff).

Everything else being equal, it takes the same voltage to ionize the gap of a resistor plug as it does a non-resistor plug, and -that- is what's important.

There are exceptions for resistor plugs but they relate to half assed design/ marketing gimmicks -by- the sparkplug manufacturer, and odds are you aren't going to use such a product.

Reply to
Neil Nelson

The problem is not so much the current, but the voltage - in a reflection, the voltage goes negative - pulse goes below zero volts (a reflection is what causes undertow in waves, like in surfer land), and the car makes try to handle this with a diode strap or some other tricks, but the reality is that semiconductors cannot handle reverse voltages well (same with the capacitor(condensor) in the distibutor). Granted, it's small and may well be within the bonds, but the reason for resistor and non-resistor plugs is an impedance balance. Anything that you do to upset the impedance control in a system will shorten it's life. If you run plugs of differing resitive values for reason, it's not going to bother me - it's your car.

BTW - the coil is connected to a FET driver - modern electrical ignitions use a computer to fire the ignition pulse - that goes to one winding of the coil. Using a resistor plug in a non-resistor application will slow the spark a litttle, but not cause big reflections, using a non-resistor plug in a resistor application is the worst case. If you need some feedback on this outside the newsgroup, I'd start looking into some signal integrity websites, or semiconductor manufacturer's websites. many of these have this same issue discussed.

Andrew

Neil Nels>>

Reply to
Andrew Paule

Reply to
Mike Walsh

The real reason for resistor plugs (and wires) is RFI reduction, not impedance matching to a non-linear device (the combustion chamber being nothing more than a gas diode with a non-homogeneous gas).

Bohdan Bodnar

Neil Nels> >

Reply to
B. B0dnar

I know that, and you know that, but our resident rocket scientist is having trouble with it. Hell, I even gave him an example of the non-linearity which he totally dodged.

Reply to
Neil Nelson

I *was* contemplating discussing the ignition wire and sparkplug as a transmission line composed of an infinite number of infinitesimal Butterworth filters of the second kind, thus having the distributed resistance and capacitance (to the engine/vehicle body) acting as a funky low-pass filter, but decided not get carried away. It did bring back memories of electromagnetic field theory stuff I really enjoyed decades ago, though...

Regards,

Bohdan Bodnar

Neil Nels> >

Reply to
B. B0dnar

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