Jubilee spark to center post not to plugs

[jrappl-HT]

Working on a neighbor's Jubilee. Was running but stalled from too high a gear going up hill and won't start. No spark to the plugs. Did a quick ignition tune up as it hadn't been done in a while - new cap, points, plugs, plug wires and copper flat conductor in distributor (old one cracked). Had a new rotor but it just fell apart before even installed so used the old - it looks fine with no visible cracks, tests good for continuity across spring post and tip, coil tested ok on primary and secondary and I get a spark out of it. Tried a new one anyway - still no spark.

I have spark at the points and can watch them fire, distributor shaft is tight and spinning, rotor turns. The coil is triggering and I have spark at the center post of the distributor but not to the plug terminals/plugs. I verified that at TDC the rotor is pointing at the #1 terminal so the gear seems ok.

It was still 6v and I'm going to convert as soon as I verify it will run so I disconnected the generator (hasn't worked in years), the old dead 6v battery and the voltage regulator and put a 12v coil on it. Acts exactly the same. Spark from points, coil triggers and spark at the center post but it's not making it to the outside terminals of the distributor. I'm at a loss, it must be grounding out somewhere in the distributor but I don't see it...

Bottom line, tried two caps, 3 coils, 2 sets of plug wires, direct wire to the coil from battery positive to test.
Any idea?

 

[Jim L WA]

Curious isn't it? The only thing I see is that you're still using the old rotor because the new one was junk. Is it making contact with the top of the cap? Check it for continuity.

 

[wore out]

Working on a neighbor's Jubilee. Was running but stalled from too high a gear going up hill and won't start. No spark to the plugs. Did a quick ignition tune up as it hadn't been done in a while - new cap, points, plugs, plug wires and copper flat conductor in distributor (old one cracked). Had a new rotor but it just fell apart before even installed so used the old - it looks fine with no visible cracks, tests good for continuity across spring post and tip, coil tested ok on primary and secondary and I get a spark out of it. Tried a new one anyway - still no spark.

I have spark at the points and can watch them fire, distributor shaft is tight and spinning, rotor turns. The coil is triggering and I have spark at the center post of the distributor but not to the plug terminals/plugs. I verified that at TDC the rotor is pointing at the #1 terminal so the gear seems ok.

It was still 6v and I'm going to convert as soon as I verify it will run so I disconnected the generator (hasn't worked in years), the old dead 6v battery and the voltage regulator and put a 12v coil on it. Acts exactly the same. Spark from points, coil triggers and spark at the center post but it's not making it to the outside terminals of the distributor. I'm at a loss, it must be grounding out somewhere in the distributor but I don't see it...

Bottom line, tried two caps, 3 coils, 2 sets of plug wires, direct wire to the coil from battery positive to test.
Any idea?

Conventional wisdom would be that the rotor is internally cracked or "carbon tracked" causing high voltage spark to find it's way to ground at the top of the distributor shaft.

Another possibility is that if the distributor caps being tried are not "correct" for this distributor and sparks occur when the rotor is is NOT in line with one of the high-tension spark plug wire terminals.

 

[jrappl-HT]

I have a new hopefully better quality rotor coming tomorrow but the old one tests good from spring post to tip and I don't get a connection running the tester anywhere else on the rotor body, inside or out. I did bend the spring up slightly to make sure it was contacting the center post of the cap and I can feel a little spring when I set the cap down on it.

It actually looks fairly new, Something is not right and that is the only thing between the center and side posts so it would seem likely to be the problem but I don't see it. Crazy that it was running fine before the stall.

 

[Sean in PA]

Try cranking the starter when it's dark. If the spark is making it's way out through a crack in the cap or anywhere else, you should be able to see it. If you can't see anything then it is sparking to ground inside the distributor as wore out suggested.

 

[old]

Working on a neighbor's Jubilee. Was running but stalled from too high a gear going up hill and won't start. No spark to the plugs. Did a quick ignition tune up as it hadn't been done in a while - new cap, points, plugs, plug wires and copper flat conductor in distributor (old one cracked). Had a new rotor but it just fell apart before even installed so used the old - it looks fine with no visible cracks, tests good for continuity across spring post and tip, coil tested ok on primary and secondary and I get a spark out of it. Tried a new one anyway - still no spark.

I have spark at the points and can watch them fire, distributor shaft is tight and spinning, rotor turns. The coil is triggering and I have spark at the center post of the distributor but not to the plug terminals/plugs. I verified that at TDC the rotor is pointing at the #1 terminal so the gear seems ok.

It was still 6v and I'm going to convert as soon as I verify it will run so I disconnected the generator (hasn't worked in years), the old dead 6v battery and the voltage regulator and put a 12v coil on it. Acts exactly the same. Spark from points, coil triggers and spark at the center post but it's not making it to the outside terminals of the distributor. I'm at a loss, it must be grounding out somewhere in the distributor but I don't see it...

Bottom line, tried two caps, 3 coils, 2 sets of plug wires, direct wire to the coil from battery positive to test.
Any idea?

Bad rotor will cause that to happen and seen that many times in my 40 plus years of messing with engines

 

[Jim.ME]

I have a new hopefully better quality rotor coming tomorrow but the old one tests good from spring post to tip and I don't get a connection running the tester anywhere else on the rotor body, inside or out. I did bend the spring up slightly to make sure it was contacting the center post of the cap and I can feel a little spring when I set the cap down on it.

It actually looks fairly new, Something is not right and that is the only thing between the center and side posts so it would seem likely to be the problem but I don't see it. Crazy that it was running fine before the stall.

Is the clip, that has a tab that the rotor slides down over, on the distributor shaft in place to hold the rotor tight and inline?

 

[jrappl-HT]

Yes, clip is in place. I also have a few years "messing with engines" Mine closer to 55 years though! I have a rotor coming and hoping that's it. Just weird that the old one looks almost new and tests good - what testing I can do on it with a multi-meter. Higher voltage might have a way of pushing through where the continuity tester doesn't.

 

[old]

Yes, clip is in place. I also have a few years "messing with engines" Mine closer to 55 years though! I have a rotor coming and hoping that's it. Just weird that the old one looks almost new and tests good - what testing I can do on it with a multi-meter. Higher voltage might have a way of pushing through where the continuity tester doesn't.

Hair line crack which you cannot see can cause it to short out. I used the 40 years as a guess to things but I started working on engines around 10 years old so that would make it more like 58 years

 

[DaveBN]

Are you sure the cap is on correctly? If the cap is not seated all the way onto the base or it's not in the proper orientation you'll have that problem. Is there a notch in the cap or the base to line up the cap? Try to measure distance from the rotor to the contact in the cap. Maybe the rotor isn't touching the contact.
Back to the original problem, it stalled under load, I would double check that timing hasn't jumped when it stalled.
All that said, I'm betting on a bad cap.
Dave

 

[jrappl-HT]

Yes, the dust cover and cap are locking into the correct position.

 

[Sean in PA]

Yes, the dust cover and cap are locking into the correct position.

Is the metal clip under the rotor still there?

 

[jrappl-HT]

Yes, the clip it there and fits well.

 

[WayneIA]

Back to the basics! Get the front cylinder (number one) on compression stroke to top dead center, Now, at which plug wire is the rotor pointing? It should be pointing to the wire attached to number on plug. What do you come up with?

 

[jrappl-HT]

As I said in the original post. I've done the basics and did check that the rotor was pointing to the correct post #1 when the #1 cylinder was at tdc.

 

[Eman85]

Old trick was to hold the coil wire at the rotor and see if spark jumps to it while cranking. If it does rotor is shorting spark to the distributor shaft.

 

[jrappl-HT]

Eman85, that is a good idea. I won;t get back to it until late this afternoon and hopefully the new rotor will be here.

 

[jrappl-HT]

New rotor came, popped it in and it started right up! Funny how the old one looked almost new, tested good and still was the issue.

 

[old]

New rotor came, popped it in and it started right up! Funny how the old one looked almost new, tested good and still was the issue.

All it takes is a hair line crack which a person cannot see but yet shorts things out

 

[wore out]

New rotor came, popped it in and it started right up! Funny how the old one looked almost new, tested good and still was the issue.

A failed spark plug wire (high resistance) or one not fully snapped in place at the end(s) subjects other ignition parts to higher than normal voltage and can cause a rotor to carbon track/short out. Or, perhaps it just was it's time to fail.