Piston Slap: Chrysler Newport – Not So Alive With Pleasure

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: http://www.allpar.com/mopar/lean-burn.html) 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: http://www.valiant.org/electrical-diagrams.html) 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.

Send your queries to mehta@ttac.com