Setting Timing

[patrickt]

FWIW, here's a closeup of my rotor tip. I think they start out touching and he has a new rotor and cap. But I don't know....

[Gaz64]

Originally Posted by patrickt

FWIW, here's a closeup of my rotor tip. I think they start out touching and he has a new rotor and cap. But I don't know....

Patrick,

That is normal "burning" of the rotor tip as the spark arc jumps the gap, not from metal to metal contact.

[Bernica]

Originally Posted by Gaz64

Patrick,

That is normal "burning" of the rotor tip as the spark arc jumps the gap, not from metal to metal contact.

That is correct. I used to rub the tip of the rotor down with some steel wool from time to time and use emory cloth to sand the faces of the contacts in the cap to ensure a good arc.

[Gaz64]

Originally Posted by Bernica

That is correct. I used to rub the tip of the rotor down with some steel wool from time to time and use emory cloth to sand the faces of the contacts in the cap to ensure a good arc.

We've all done that, I learned to do that as a young mechanic.

Believe it or not, a small corrosive buildup on the terminals is still a better conductor than air.

So scraping terminals is a no-no. More frequent inspection and replacement of cap and rotor is the go.

[DanEC]

You might check continuity of your rotor from center contact to rotor tip. I never heard of this until the other day but I read where someone found a rotor that was very high resistance between the two - should be near zero.

Hard to see how a coil could cause your problem - it feeds the cap but doesn't have any way of knowing which cylinder is next in line to fire.

I can't see how you can even get the motor to run on two cylinders (?) That sounds unlikely - more likely would be most cylinders are firing but getting a weak spark. Did you use your timing light to check each cylinder to see if it flashed, indicating power to the wire? Since you have had the plug wires off and on so many times I would check each one out for resistance and while checking them be sure to move the wire around at the plug boot. Some types of wires/connectors can be damaged pretty easily at the plug boots. Also push the plug boot back if you can and make sure the terminal is still securely crimped to the wire.

[1795]

Phil,

I would agree with Dan, and the others in that you should check the wires, cap and I would also suggest the spark plugs. Dan is probably correct in that some of the time the other cylinders must be firing, the engine would not run on just 2 opposing cylinders very well. It wold sound like my fathers old 2 cylinder John Deere tractor, chug, chug, chug, chug. What may be happening now is that since there have been multiple attempts to start then engine with little or no electrical output to the spark plugs, most of the spark plugs are probably fouled. Get a new set of plugs and try them as well. Also, there is a gap between the rotor and contacts for the spark to jump across. Maybe the cap is bad in that the contacts for the most part are recessed too far? Can you take a micrometer and measure the distance from opposing contacts and see if there is a difference? If the gap gets too far the spark will be weaker and possibly non-existent.


this is a baffling problem, there are very few scenarios that would result in only 2 cylinders firing, and even those situations are basically ruled out. If the cap were out of round, you might get a situation where only the 2 contacts that were opposite each other and closest to the rotor would be the only ones able to get spark, but your 2 contact points are right next to each other. The only way that the coil would be implicated is if it was sending weak charge to all cylinders, which is not your case (unless all of the plugs are getting fouled and these are just the last 2). A bad rotor would not be bad on only 6 of 8 contacts.

I just am not knowledgeable enough about computers to know if the programming in the MSD could be off and only allowing spark to go to 2 cylinders, but that does not seem likely.

[DanEC]

I forgot about the two cylinders Phil believes are firing are consecutive in the firing order. That means out of 720 degrees for firing all 8 cylinders, it's only firing on 180 degrees of that and the other 540 degrees are just coasting. I don't think that's possible unless the engine rpm is elevated way up there first.

[Large Arbor]

Gary,

Yes, I did the MSD spark test and had spark.

Patrick - Yes, the engine was running well last week prior to the pushrod episode.

Continuity at the rotor button to cap is fine - checked that last night.

Phil