ROTOR WOES

[Phil 32DL6]

MY 32 DL6 has been running very smoothly this season. The other day I was off on a short jaunt when...suddenly, and without any warning, the engine just quit as I came to a red light. Fortunately, no one was coming, so I was able to coast around the corner and get to the side of the street to check things out.

I could hear the electric fuel pump chugging away, but the engine wouldn't restart. After some quick-analysis, I grabbed a swatch of crocus cloth, popped the hood, and, sure enough, the rotor was pitted and fouled. A bit of polishing and she started right up.

That got me thinking. Rotors seem to get pitted and fouled fairly frequently on that car. But, how often is too often? I'm guessing that cleaning is needed every 250-300 miles, or so. Then there's the pitting: pretty deep, and always on the leading corner. The 32 has a Delco distributor.

Seems I've read somewhere that timing being slightly off may have some influence. True? Is there anything else? Coil or condenser?

What's the word on the street?

[ply33]

Not sure what is going wrong with the rotor in your distributor, but my experience is that when I replace rotors in my 1933 with its original Delco-Remy distributor, typically at about 10,000 miles, they still look pretty good and usable. If you are only getting 250 to 300 miles, then something is very wrong.

Any issue with the contact in the cap or with the points? Is the rotor/cap combination the correct? Maybe they distance between the rotor conductor and the conductors in the cap are not spaced correctly...

[Ian_Greenlaw]

Not sure if this helps but a friend of mine was having a similar problem. After a lot of playing around with different variables he found the top distriburor shaft which the rotor sits on was slightly warped causing uneven wear to the rotor. Once he replaced it, there seem to be less problems. Not sure if yours could be this as his was a later model.

Ian

[Guest DodgeKCL]

I think the clue to your problem may be "always on the leading corner". This means the timing point is on the same spot. I believe the timing spot was originally somewhere in the middle of the brass arm? This gave a larger area to disperse the current arc and not burn a small area. I believe the fault lies in this small spot going higher and higher in resistance as it's carboned up and finally not enough current will flow over the gap to fire the spark plugs especially if they are the least bit dirty or their gap has started to widen because of age. The timing should be closer to the middle of the brass sweep and yours appears to be quite a bit advanced. This engine is somewhere around 10 degrees btdc ,you have it set ahead of that? Don't forget point gap can change timing. And lastly, normally rotors last years and thousand of miles with,as you say, a little crocus cloth.

[MikeC5]

Could a bad condenser cause this?

[Phil 32DL6]

Well...Today I had some time to check out the timing and decided to start from scratch.

My car owner's manual says to set the point gap first to .20. That checked out okay and the points were clean. Next step was to turn the motor until the DC mark on the flywheel lined up with the ignition mark (actually one of two pointer tabs) on the timing indicator plate (see photo #1). That's when I noticed that it appeared the wrong pointer was aligned with the mark on the flywheel.

I also noticed this time (after doing some additional cleaning of the whole distributor) that there is a small scale behind the hold-down arm underneath the distributor. Never saw that before because it was hiding under some crud. After using some steel wool on it, I could see that the indicator on the arm was pointing to 6 degrees BTC on the scale. In effect...slightly retarded!

This time I was careful to align the right marks and I used an ohmmeter to tell when the points were just opening. (It's important to remove any shaft slack by rotating the rotor clockwise while turning the distributor counter-clockwise to advance the timing. When things are set properly, slight clockwise pressure of the rotor against the spring-loaded advance weights will trigger the ohmmeter.) Exactly 10 degrees BTC on the scale was the result (photo #2). I threw on a new cap and rotor, cleaned and gaped the plugs.

She fired right up and drove beautifully around the block.

Of course, the REAL test will be time. After a few hundred miles, if the same rotor pitting begins again, I'll know I have to start scratching my noggin again.

Edited October 1, 2011 by Phil 32DL6 (see edit history)

[Guest DodgeKCL]

As a history note, I have discovered the points,cap and coil circuit are the same exact circuit as Marconi's spark transmitter the type used on the Titanic to transmit CKD and then for the first time,SOS. The points are the telegraph operator's key, the cap and coil are the 'tank circuit', a radio term, and the coil's lead back to the dist's tower is the antenna. I have often wondered if Kettering really just adapted Marconi's circuit to his internal combustion engine firing circuit. He adapted the small high current motors from his days with cash registers to his starter motor. Hmmmmmmmmmm.

[Phil 32DL6]

I have often wondered if Kettering really just adapted Marconi's circuit to his internal combustion engine firing circuit. He adapted the small high current motors from his days with cash registers to his starter motor. Hmmmmmmmmmm.

"If I have seen a little further it is by standing on the shoulders of Giants."--Isaac Newton, 1676.

[idrjoe_sandiego]

Dodge KCL you are no doubt right on the money with the advent of Kettering's system. One note as a slight correction: Marconi, while successfully commercializing the use of wireless transmission of electrical energy actually "adapted" (i.e., stole) most of his work from Nikola Tesla.

In 1943, a lawsuit regarding Marconi's numerous other radio patents was resolved in the United States. The court decision was based on the prior work conducted by others, including Nikola Tesla from which some of Marconi patents (such as U.S. Patent 763,772) stemmed.

The case was resolved in the U.S. Supreme Court by overturning most of Marconi's patents.