Frog wrote:Ken,
That is an interesting read, thank you for taking the time.
In your opinion, do you think that my issue could be caused by a poor ground? Or, are you saying that it is the spark plug that is grounded?
Frog, sorry, I missed this post as I was getting involved in refining my understanding of ignition systems.
I'm not sure I'm going to be of any help with your problem, but I'm going to say a few things.
Insufficient or intermittent grounds can drive a person crazy when chasing electrical problems. And one of the worst things that they can do is give a person symptoms that make just no sense at all. However in the case of your (apparent) ignition problem I guess I just don't see the opportunity for a ground to be so problematic. In the discussion with Garnet and Brad we've established that grounding of the coil cases is a non player. So the only grounding to be talked about has to do with with the points and condenser grounds. And there, there's not much to look for. There's the wire from the coils to the points and then the connection of the points body to the engine. For the condenser there's the strap that wraps around the condenser, grounding it to the engine. Not a lot that can go wrong grounding wise and relatively easy to verify as being OK.
Now then, other than the grounds, there are several connections having to do with the positive side of your ignition system, from the battery, through the ignition switch, kill switch, and to the series wired coils. There is a lot of opportunity for bad connections or troublesome wiring to cause problems.
However, in reading and rereading your symptoms I'm struck by the fact that one cylinder runs well and the other does not, even when substituting a "known good" coil. The stuff I've talked about above should have affected both cylinders equally.
You have swapped something from side to side on the cylinders and the problem persisted in the L/H cylinder. That is a big clue and a big opportunity if only the problem will have the decency to stay broken.
You have probably already done this and I've missed it. I would want you to have the problem you're experiencing and then swap the plug wires
only onto the opposite side. If the problem cleanly transfers to the other side then you know that you have an ignition problem and it will be occurring somewhere in your coil set or spark plug leads. In that case you just have to replace spark plug leads or coils and the problem should go away. You've already done a lot of that, but have you done it by swapping the spark plug leads only?
Now then, if the problem doesn't transfer to the other side you have a lot more things that can be your problem including carbs. In the advice that has been given to you there has been some talk about that kind of stuff already.
One thing to keep in the back of your mind as you work with this problem is that coils have a devilish habit of sometimes working and sometimes not. Typically they will work OK when they're cold but start to give you problems as they warm up. If you're in the middle of your troubleshooting routine this can screw with your head and confuse the results of what you're doing.
"Known good" coils make me nervous. How do you know that the coil is really good?
As to the heating of the coil being a problem, the way I understand it is that as the coil is used the natural heating of the wires causes the windings to "squirm" around inside the coil case. A winding may separate as it squirms around and then squirm back into place as the coil cools again. With the electricity now flowing properly the coil acts like a good coil. (I've chased my tail on two separate occasions, not recognizing that my coil went bad as it heated up.)
If you're running with the original or old coils this might be the time to think about replacing them, whether you're sure you have a coil problem or not. Usually coils are the last things to be replaced because they are the most expensive. For myself, I have a spare new set of coils in my stock because, having been bitten in the ass twice, I figure I'm going to need them sooner or later. Some folks here at Boxerworks have developed the policy of simply replacing old coils even though they seem to be working OK, because coils do age and go bad.
Another thing I need to mention in passing is that I take a very dim view of bench testing coils and pronouncing them OK. A bench test usually consists of ohming the primary and secondary windings and comparing the resistance you get with what the resistance is specified to be. Again, the reason is that coils can and do sometimes change characteristics with heat. In short, a bench can prove a coil bad, but it can't prove it good.
I'm writing a lot of words here and I haven't really given you any real analysis based on your symptoms. Frankly I don't have a lot of good ideas. But if you can come back and say that you have swapped the spark plug leads only, and the problem did or didn't swap sides, I think that might generate some good ideas from me, perhaps, and others here.
I hope my tone wasn't that of talking down to you. That certainly was not my intention.
Ken
