Packard Forum Index » Post-War (1946-54)

I have a '47 Custom and its 356 has been running rough. At first it was fuel related, so I replaced the fuel pump and carburetor. It ran much better and I drove it three weeks without incident, but it did not idle as smooth as it should. I replaced spark plugs (10 mm) then distributor cap, rotor and ignition points. My mechanic installed the ignition points for me, and I drove it the ten minutes home. Seemed fine. The next time I fired it up a few days later, it never did smooth out. We drove it a few miles and it ran worse and worse, til it nearly was convulsing. Then it stopped running completely.

When we got it home, we found that the points weren't sparking between them. There was a ground from each side of the points but no spark between, so I installed another set from Merrit. That set seems to be failing too after only a few miles of driving, as the car runs extremely rough.

Either I'm on a run of really poor luck on ignition points or something else is taking place. This is a rebuilt motor in a restored car that when running well performs beautifully.

Thoughts??

Thanks for your guidance-

Steve

If you didn't replace the condensor, that could be it. Always replace it when you change points.

If the condenser is open, bad, wrong value or not have a good connection to both side of the points, that will cause premature failure. Even new condensers can have problems. If the coil primary is partially shorted, that will cause an excessive current draw and could overheat or burn the points.

Thank you - forgot to mention the condenser was replaced too. It was all part of a tune up kit from Max Merrit. Neither set of points show any sign of burned contact points; they're clean. I guess I could replace the condenser again and see if that impacts it.

When points are newly installed, everything works for a time. Coil appears to be normal. When it starts to run rough and we pull the coil wire from the distributor it's sparking only some of the time - not each time. Very perplexing.

I'm curious on your first post you said there was ground on both sides of the points but no spark between. There should only be real ground on one side. The other side should be voltage if the ign is on and points are open. When the points close, the voltage should drop to 0 or ground. If you checked with an ohm meter with ign off then you are probably reading thru the coil but it is not an actual ground. Is that what you are seeing?

Since the issue seems to go away with new points any chance there is something with the distributor - either wear or something letting the settings or point gap change. Does the problem happen with car still and engine just idling or does it always depend on being in motion. I am wondering if something could be vibrating and shorting or has a loose and intermittent contact.

Be aware also, If you have an old original style coil, those are notorious for some strange and intermittent failures. Usually the symptom reported is once they get hot they just quit. An hour later when things cool, all is well again. Conceivably yours could be acting up to the point of rough running but the coil hasn't reached the absolutely quit working stage. Doesn't seem likely it would depend on new points to work properly though something to consider.

One other lesser possibility is the ignition switch or the armored cable between the switch and coil. The coil has it's own terminal in the switch and that could be heating up causing voltage to diminish or drop out. The wire inside the armored cable has been known to short against the armor.

If you wanted to totally rule out coil and ign switch, Since original style coils are so expensive, a quick, dirty and relatively inexpensive way to rule out coil is get a universal 6v coil from Napa for less than $20. Use some tie wraps around something handy to rig some kind of support for the coil in the engine compt. The case does need to be against a metal ground though. Reroute both distributor wires to the new coil and for power use a jumper to hot wire the coil directly and see if the problem goes away. If it does, the coil is suspect. If still a problem, go a bit farther by removing the power wire from the original coil end and extend it to the engine compt to power the test coil. Easiest way would be to remove the old coil and extend the wire thru that hole.

If you still have a problem then at least you have ruled out two places known for issues.

If it has OD-disable the part that shorts the coil out.

When I was having problems, I imagined that the changes I made improved performance for a time, then the problems came back...mainly because they were not solved.

One problem was the bolts securing the distributor to the engine. It was so simple. The vacuum advance would rotate the distributor instead of pushing the arm that advances the points because the distributor wasn't secure. I remember, it's not that visible. If someone working on the distributor forgets to tighten both of them up, the distributor will rotate to a point when it won't even run.

I also had the OD relay problem, when I wasn't getting any ignition, even tho coil was fine. The relay contacts were stuck from getting shorted when I pulled the OD solenoid. I should have disconnected the battery or the OD cable switch wires first. The OD cuts the ignition completely. As soon as the contacts were free, everything worked fine. The easy way to eliminate that as a problem is to temp disconnect the wire from the OD relay to the low voltage terminal of the distributor.

But I'd check those bolts or cap screws whatever they are called.

Attach file:

---

  (23.00 KB)


  (31.85 KB)

Joe, in the bottom photo, loose bolts or not, it doesn't appear that the distributor body is even fully nested into the clamping ring. I don't know whether or not it can lead to burned points as such, but clearly a poorly grounded distributor can give just horrible performance. On the prewar senior engines Packard at one time even went so far as to recommend a grounding lead.

Thanks, Dave,
I'll check that it's fully seated and that the screw holding the clamp is tight.

I guess this is proof that it pays to help other Packard-peeps. But this is the condition in which it went 2000 miles last summer to Pebble Beach and back. I guess those old seniors could be forgiving, too.

I'm in the process of pulling the clutch and rear springs, and will be dealing with some older issues re doors and windows, for the next big adventure in Aug.

One thing I did on my 47 Custom Clipper to make timing adjustments easier was to install a longer 1/4" bolt so the bolt head would be past the distributor housing. This makes changing the timing much easier. I used a piece of tubing between the bolt head and bracket to take up the extra length. The hex head on the bolt is easier to tighten and loosen than the slot-headed screw originally used. Something to consider next time you have the distributor out.

(o{}o)