By on September 29, 2010

TTAC Commentator halftruth writes:

Hi Sajeev, I currently own a 1965 Chrysler Newport stock set up with single points and no mods to the engine. For the most part the car runs well but, I have run the gamut of replacing typical tune up items such as filter, plugs, belts and the like but have a very annoying problem: I have been thru 10, yes 10 sets of spark plug wires and they have all arced causing the car to idle funny and affect it’s overall driving performance.

Wires were purchased locally thru Napa, Autozone (BOS area) and online thru Jegs.  Same thing every time. The last set I bought were some 8mm Accels you assemble w/ a crimper borrowed from a friend. They too arc. At this point I am thinking it cannot be the wires. So I installed a ground cable (there was already one installed- a thin mesh type strap) from the body to the pass side head. It was my thought that maybe, just maybe there was static build up but I still see flashes at night. They are random and not originating from the same wire or position on the wire. I even threw some of the old plugs back in thinking I had a grounding plug but nope, the arcs continue; randomly and with no pattern.

Some folks have argued the coil can do this but it is new. Some claim the ballast resistor can do this too. Perhaps by not limiting voltage when in run mode? Some old school mechanics tell me that if there is arcing, the wires are bad but now I am skeptical.

I am going to throw this to the B&B and see if y’all can shed some light.

Sajeev Answers:

Are you sure someone didn’t sneak a Chrysler Lean Burn system (LINK: in there instead? Because this shouldn’t be very difficult at all.  And yet, here we are.

This is the first time in the history of this series that I couldn’t find a reasonable answer to mechanical quandary via gut-analysis-to-keyword-searches. So I called my Jeff Pate, owner of Classic Cars of Houston and restorer of older vintage metal. This kind of problem simply shouldn’t happen.  Jeff wasn’t sure why this is happening either, but all three of us touched on a logical conclusion.

A distributor doesn’t vary output, and the distributor’s points are an on/off switch for the current. The only thing not addressed is the ballast resistor, a very simple part in a somewhat simplistic electrical system (LINK: that could affect operation of the ignition coil and everything downstream, including spark plug wires.

Before you condemn the ballast resistor, check the plugs for their condition and the correct gap.  Check the cap for cracking. If those two look peachy, spend the $5-15 for a ballast resistor and pray to the deity (or not) of your choice: you’re gonna need it.

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28 Comments on “Piston Slap: Chrysler Newport – Not So Alive With Pleasure...”

  • avatar
    Educator(of teachers)Dan

    Good luck, Halftruth.  Give us an update and let us know how it turns out.  I aspire to classic auto ownership so I’m always facinated by these seemingly “unexplainable” problems.

    Would a possible fix be to eliminate the “points and condenser” system with a reliable aftermarket product?

  • avatar

    Are the spark plus used resistor or non-resistor type?

  • avatar

    I have no surefire (pun?) answer, but a couple of guesses.  I had a similar problem on a 68 Newport some years back.  I had replaced wires, but the car ran rough and the distributor cap kept getting a buildup of some kind of deposit inside.  I replaced the cap 2 or 3 times but the stuff kept coming.  A wise old mechanic told my my wires were bad, and I bought better wires and replaced them, along with a new cap.  My problem was solved. 

    Have you looked inside your distributor cap?  My guess is that the arcing is happening inside the cap, which is sending electricity down the wrong wires at the wrong time.  Have you replaced your cap since the last wire job?   wonder if a new cap and rotor would help.  While you are in, replace the condenser just in case.  You also did not say if this happened during certain weather conditions.  These cars never liked cold damp weather much, and I learned to always spray some WD40 into the inside of the distributor cap.  This displaced moisture that liked to get into the distributor on these, and the car would always run well in wet weather.

    As for the ballast resistor, I never had one fail in this way.  The common failure mode is that the engine will catch then die when you are trying to start it, and the car will not run at all.  But a ballast resistor is cheap, and if it is not the culprit, you will need to keep one in the glove box anyway as Paul Niedermeyer recently learned.

    By the way, I am jealous.  It has been about 15 years since I got to regularly experience the bliss that is a Chrysler big block mated to a Torqueflite. 
    Oh, and a bonus tip (a Piston Slap Nugget of Wisdom, perhaps)- did you know that the first stop for all 12 volts of electricity in this car is the ammeter in your dashboard?  This is why these old Mopar ammeters were so sensitive and would show virtually any current draw anywhere in the car.  These cars have a tendency for these fasteners that hold the wires to the copper contacts to loosten a bit as the car gets old (and yours is).  If you hear something that sounds like a geiger counter in your dash, take this ammeter out NOW and tighten everything down.  If it is quiet and you have the dash apart for any other reason, do the same.  If this is ignored, bad things involving 12 full volts can happen behind your dashboard. 

    • 0 avatar

      +1 for the wiring info on old Mopars.  Another mistake I have seen hot rodders make is to install a high amp alternator in one of these older rides without taking the ammeter out of the circuit.  You don’t want 100+ amps running through that old wiring and into the dashboard — that’s a recepe for a burnt out wiring harness and interior fire.  Keep it to around 50 amps (Powermaster Retro unit comes to mind….) and you’ll be fine!!

      Relative to the arcing, it’s quite unusual that with all the parts replaced it’s still happening.  To me it still points to the wires (I use Mother Mopar for this).  If the arcing is visible under the hood at night, that can only be caused by bad wires or too much voltage that the wires can’t handle.  Just for fun, I’d be tempted to try another coil since there might be an internal winding problem that is causing an over voltage.  After all, the coil is nothing but a step-up transformer, so maybe there is a strange shorting problem on the inside changing the amount of step-up being provided — even if it is new.  Strange, to say the least.

  • avatar

    Also, check the voltage on the ‘+’ side of the coil with the engine running … should be around 9-to-9.5V (and should be closer to 12V while cranking). If the voltage checks out, your ballast resistor if fine. If the voltage is too high, replace the resistor (although this would be a weird failure mode, it could happen).

  • avatar

    Arcing of wires in good condition indicates excessive voltage.  Contrary to the assertations of the purveyors of brightly colored aftermarket coils, what really determines voltage is the internal cylinder pressure and the plug gap.  Make sure you have new plugs with sharp electrodes and the gap is .035″.  You might even try narrowing the gap to .025″ if arcing persists.

  • avatar

    Unfortunately, there are no truly OE replacement parts made anymore. Im not impressed with the quality of modern replacement caps, rotors, point sets, etc. They are a very low priority for the current makers.
    Back to the original question. What kind of arcing failure exactly? Does the outer insulation fail, causing crossfire or leakage to the engine, or is it an internal open circuit within the wire itself?
    An old-school diagnostic trick is to open the hood in the dark with the engine running and watch for “corona” external glow or sparking on the outside of the wires, cap or coil.
    A ballast resistor is an all or nothing part, it works or not. period. The condenser is the only “variable” in the system, but mostly just influences point life if it is out of spec.
    I agree about reducing plug gap. For some reason US automakers always specified bigger gaps than the imports. I think it was to force a higher energy spark in order to fire weak mixtures more reliably in big-bore, high compression cylinders.

  • avatar

    I would measure the voltage coming off of distributor going to the plugs. As TR4 mentions, the arcing is caused by voltage that is too high (and you have some real high voltage if you have 8 mm accel’s arcing, probably more than 40,000 volts). For this to be the case it would have to be something like the ballast resistor but I think you would have other operational problems too if it were in fact that. Excessive voltage will cook the points too.

    Also, perhaps the condensor? It is supposed to absorb excess energy when the points close (ground) and maybe it’s no longer doing what it is supposed to do. Also, when the wires arc, do they all arc or just certain ones and is it usually the same ones? That would point to something cylinder specific like the cap or something that is coating certain wires and breaking down the insulation (probably a stretch).

    • 0 avatar

      “measure the voltage coming off of distributor going to the plugs”

      Don’t attempt this unless you have a voltage divider and a scope or something to capture peak (actually peak negative voltage).  You will definitely get tickled and blow any voltmeter otherwise.

    • 0 avatar


      Good point to include. I should have added “with the apprpriate equipment” and not a basic voltage testor. 

  • avatar
    John Horner

    There is a wire which comes to the coil from the starter which provides a direct to battery voltage bypass of the ballast resistor. Perhaps this wire is getting fed all of the time instead of only when the starter motor is turning like it should be. A quick measurement of the + side voltage on the coil primary will show if this is the case or not.
    Also, is the engine misfiring when these arcing events are observed? How are they being seen, by opening the hood in a dark garage?
    Who knows, maybe you are just the first person who can actually see an engine’s aura :).

  • avatar

    Did you replace the coil with a high performance Accel or other aftermarket part? If so, go back to a run of the mill coil. As mentioned, the voltage going to the plugs is too high. You also have to make sure that the routing of the wires is correct. They should not cross in an ideal situation. Your wire standoffs should be replace if they are old. I also strongly suggest that you get rid of the points and condenser system. It is an antique, and will cause you much grief down the line. It was developed in an era when better systems were not available. Now there are. Good luck!

  • avatar

    The key is the age of the car. In the early ’80s, I drove a 1963 Newport, and it had all kinds of electrical gremlins that made it run very rough. It was a short term ride for me so I kept driving it that way until I ran into a problem I couldn’t ignore: a fuse kept burning out, killing my headlights. I finally took it to an auto-electric specialist who checked every wire in that car. He finally found the problem after three days. A bare wire to the glove compartment light occasionally touched metal.
    Along the way, he tightened/cleaned every connection, and quite a few were corroded or loose, and told me the voltage regulator, coil and distributor cap should be replaced “soon”, and I had him replace all three for me right there. Afterward, the car ran like a champ! I held onto the car after buying a replacement, and parked it for weeks at a time until I remembered to start it.  When I sold it, the car had been sitting for a month, and when I just put the key in and turned it without my foot on the accelerator, it started right up. The prospective buyer bought it on the spot.
    The bottom line for a car this old, if you want to keep it, is to put a meter on every wire and tighten and/or clean ALL the connections. The hardest part is finding somebody who will do the troubleshooting the laborious old way, checking every wire with a meter.  Also, drive conservatively – as I found out quickly, the 361 4bbl can fly, but the drum brakes are nearly overmatched by the weight of that beast.

  • avatar

    Hey everyone, thanks for all the tips here.. I will most certainly keep them in my back pocket..
    I will tell you how I found the problem.. I grabbed an old spray bottle, filled it with some water and decided to start spraying around the coil. It was the only item I had not swapped out as I assumed the new piece to NOT be the problem. The negative side was arcing straight to the coil output. It was arcing quite a bit so I put the old coil back in and presto- smooth idle and no more light show.. I still see some occasional flashes here and there but nothing like before and the car runs perfect. I had swapped the coil out proactively when I was putting the engine back together as it was cheap enough and figured why not.. It was tough to see the arcing as the wire boots were in the way. So there it is.. I know it sounds like something I should have looked at sooner but I was always taught that arcing wires should be replaced. After so many sets I had no choice but to look elsewhere.. thanks again to all.
    And yes jpcavanaugh, the ol’ Mopar big block and Torqueflight are a heck of a combo.

  • avatar

    Pertronix makes a electric ignition that fits under your old distributor cap.  I used one on my ’73 Galaxie after I got tired of setting points.  No more points or condenser.

  • avatar

    Have you checked the points, condensor, and dwell angle?  I would first check the spark plug gap and set it properly (you have the shop manual, yes?).  Next, I would focus on the distributor internals for your trouble.  If you have a known good cap and rotor, make sure the internals are adjusted to spec.  Someone mentioned adjusting the gap of the spark plugs, I would favor checking the gap on your points first.  Are you keeping the engine stock for a reason?  Those Pertronix units work great and can be undone and is an excellent, noninvasive, improvement for not much money.

  • avatar

    First of all, there is a place for people with your excellent taste in cars —
    I would have to agree with others that you need to check the gap on the plugs and points, double-check that you’re using the correct plugs, and that they’re not fouled.  You need Champion RJ14Y or equivalent, gapped at 0.035″ if my memory is good.  “High output” coil or not, the ignition system will only build voltage until it finds a path to ground.  Naturally that is supposed to be at the spark plug tip.  I suspect that simply changing the coil is not the complete solution, and you’ll have problems down the road.  If you’ve been running the car with it arcing through the plug boots or wires, there’s a good chance that the insulation on the wires is compromised and they will fail, leading to the same problem again.
    There are also supposed to be metal heat shields around several of the spark plugs which are close to the exhaust manifolds.  These heat shields fasten under head bolts.  If the heads have been off your engine, the heat shields may not have been reinstalled with the heads, leading to premature failure of the plug boots.
    As for the ballast resistor, a shorted ballast will cause a stock coil to overheat and fail from overvoltage in the primary windings, but as I said above, voltage in the secondary will only build until it finds a path to ground.  If the rest of the ignition system is healthy, then overvoltage on the primary still should not cause the described symptoms.
    I also agree that a breakerless electronic ignition conversion to eliminate the hassle of points is the way to go.  However, if you’re running the original 45 year old distributor in the car, chances are the bushings are shot, so putting a Pertronix in it will be a waste of money.  There are several “ready to run” distributors available that are basically equivalent to a new distributor with a Pertronix-equivalent module installed.  That is my recommendation.

    • 0 avatar

      The dist tower was cheap new so I replaced the whole thing. My thing about driving this old girl was I wanted to drive it just as they were driven back in the day. Eventually, I will go to HEI and a four barrell but for me the experience is one of nostalgia. The radio doesn’t even work and both me and the wife could care less. We simply like “time traveling” on the weekends.. Thanks for the input, hopefully this will be the end of it.

    • 0 avatar

      The Pertronix and similar systems, including Chrysler’s version using an externally-mounted control box, do little more than replace the points.  Believe me, you won’t miss them.  :)  This is not “HEI”.
      HEI (High Energy Ignition), is not quite the same animal.  On your stockish Chrysler big block, HEI is totally unneccessary.  HEI was developed by GM in the early 70’s.  They were running their engines lean to reduce CO emissions, and the lean mixture required a hotter spark to fire.
      HEI does away with a ballast resistor, and the control module incorporates a constant current source to supply power to the coil.  By having more control over the coil power, the system can generate higher peak voltage without risking damage to the coil.  To take advantage of this, you must run a wider gap on the plugs.

    • 0 avatar

      I chose to do away with the points on my Fury by getting the “Direct Connection” distributor and firewall mounted electronic module.  My car was built during the transition year where the early ones got points, the later received the electronic ignition.  I wired it to emulate the factory install and it looked and worked great!!

  • avatar

    On my old MOPAR, I replaced the original distributor with the electronic distributor sold through MOPAR performance. It fita all big block and small block Chrysler engines back to the 50s. Big improvement in starting and idle, and performance inthe wet. Has an advance curve intended for performance instead of emissions, and the internal bearings are far superior to old Chrysler distributors. Not original, but it sure works nice.


    • 0 avatar

      Out of the box, the advance curve of the Mopar electronic distributor is awful for anything except a drag car.  The mechanical travel is too far and the springs are too weak.  Fortunately, the guts of the new Mopar distributors are made by Mallory, so it’s easy to buy a recurve kit to set it right.

  • avatar

    TR4 and nikita above nailed the two issues:

    1) The quality of replacement parts has been going down for the past 20 years.  I had multiple failures of name-brand “American” replacement parts (Gates, Standard Ignition, etc) on my 1971 Ford station wagon, back in the early 1990s.  And I had the exact same problem with the wires (Standard Ignition, purchased at NAPA) – after about a year, they would break down and at night you could see the current tracking on the outside of the wires (it would punch through the insulation, travel on the outside of the wire for a bit, and then jump back to the inside).  I would replace the wires with new ones and the same thing would happen.

    2) Forget all of the talk about other low-voltage wiring on the vehicle as that has nothing to do with your issue – the ignition system high voltage only goes as high as it needs to in order to fire the plug.  For that vehicle, you should be seeing 3-5kV at idle, and it should spike up to 10-15kV when you stab the throttle.  This firing voltage can be checked with an automotive oscilloscope or some portable induction-type voltage testers (I have one, is VERY handy).  I cut my teeth in high school auto shop working on exactly that type of car, and we always hooked up the oscilloscope during a tuneup to monitor firing voltages.

    So I second the advice to check plug gap, set it at .030″ and no greater.  The higher the plug gap, the higher the voltage level it takes to fire the plug, and the more the plug wires are stressed.

    Now, something that hasn’t been mentioned yet – if you have a lean air-fuel ratio, you will have high firing voltages across the board.  It may not be noticeable at idle, but may only exist at higher RPMs when the carb is operating on the high-speed circuit.  So monitor the firing voltages with the engine at 3-4K rpm with every electrical load on (to add load to the engine) and see what it is – if you’re over 20kV, something is amiss.

    Finally, because of the aforementioned failures I have seen with aftermarket parts, I have gone back to purchasing from the dealers (usually online to save $).  I know that this isn’t possible for that vehicle, but know that you aren’t alone in your frustration!

  • avatar

    That Newport reference was sooooo kool.

  • avatar
    Don C

    I’ll echo what BMWfan said, an aftermarket high output coil will cause this problem. Use stock parts.

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