As a follow up to my earlier post on routing the timer wiring, I put every thing back together and started Lizzie up but she still ran very uneven! So frustrated as I was, I did the screwdriver test again on all four spark plugs and again, number 4 was not responding. Then it hit me to check the coil box for number 4 and looky what I found! I guess that explains why the car was running so poorly, but what exactly caused this? It's the mag post connection that is burnt. Any suggestions? Also, do you think the coil is still usable? Thanks ahead if time!
Bill I like that! looks like an arc welder was in there, John Reagon was talking about the material that some vendors make there coil boxes out of is not up to par, is this from him or others ?? Thanks Joe
It's one of his! What do you think caused it and how do I fix it? This sure explains why it was running so poorly!
I suggest you contact John directly. I'm sure he can help you out.
That's Fun Projects, right? I found the bill of sale - purchased in June of 2014.
Yes it is Bill. I suspect the only remedy is to replace that part of the box, but the mystery still remains as to what caused it in the first place. May never really know either. BTW...my top's done, just ordered a new boot, and just a bit oversized too! Tired of stretching that ants ass!!
Bill, is it possible that the wire got pinched between the lower plastic panel and the metal box, causing it to ground out?..Just a thought.
That post supplies power to all the coils. I don't understand why it would affect only #4.
I would suspect the car ran for a while with no connection to the #1 plug, the hi voltage sought a path and found it, leaving a nasty carbon trail along the way.
Would love to hear how the pros see it.
Make that #4 plug
Check your coil box wiring again. The Magneto contact should go directly to the Magneto side of the switch. The Battery contact goes directly to the Battery side of the switch. Then, the common wire from the switch goes to the bottom contact strip in the coil box. You do not want the two switch wires to ever touch. Both the Mag and Bat are hot. The ground comes from the timer.
Also check the "goodness" of the Mag post to mag-to-switch wire. If that is loose or intermittent, you might build up enough heat from sparking to melt the plastic. You want it to be soldered properly. Same for the eight coil and one Bat contacts to their posts.
I've been running the Fun Projects coil box kit for several years and never had a problem.
To burn up that much wood on the coil the spark plug wire would have to be completely open so the spark had to jump somewhere and chose to jump through the wood to the magneto. I am looking at the same pictures you are. The coil unit box sides are thin on both sides so I wonder what kind of coil this was. If the spark wire lead inside the wood box was routed incorrectly along the edge inside or broke off from the normal side spark connection coil box internal contact it would then act like there was no ground at the end of the spark plug wire electrically. In that event then the spark appears to have jumped through the wood coil unit to the nearest ground which would be the magneto connection. I am just guessing since I would like to see all components first hand to make a better diagnosis. Wood box coils can be destroyed quickly if they are powered up with no external gap on the coil but this one is really about the worst one I have ever seen. If I had to guess I would say the wiring inside the coil unit broke and the spark energy was finding the next best ground it could find since the plug wire was no longer connected. The arc was across the surface of the plastic and then appears to have melted down through it when the arcing was recurrent. Is this car using modern spark plug wire by any chance?
I had a bout the same problem with a wooden rebuild kit.
The problem started after a thunder storm were the box took some moister.
For me there was no problem with the coil because it is still in the car and is buzzing well
John, the coils are rebuilt by "The Coil Doctor" and are only two years old. Also, the spark plug wires are the cloth type and also are new. Is the box itself safe to reuse? I'm going to pull the entire box off today to have a better look at it.
Here are some closer photos of the coil itself.
I would get rid of those copper contacts and get a set of brass originals.
I suggest sending the Coil back to Brent, THE COIL DR. He is a very conscientious guy, could take it apart and give us more info. I have never seen anything like that and found John Regan's explanation interesting.
Appears to me that Bill re-used original Ford contacts and even the screws in the rebuilt with the plastic kit.
Looking at the #4 coil location, the forked terminal there is worn away on the right hand fork, maybe that was there earlier? If so, a deformed contact like that could have allowed the contact button of the coil box rest on a smaller area. Combined with a loose wire to the spark plug, or whatever, the coil buzzed that spot to death
Does the secondary winding or plug wire measure open with an OHM meter?
I am working with Bill to see what happened but unfortunately the "crime scene" has been pretty well disturbed by various things tried so I can only tell for sure that at some point a coil was firing directly across the surface of the plastic to the magneto connection which at that point was the nearest ground. That means that the spark plug connection looked to not be connected at that time. That may have been before or after the timer was rewired. This might have happened earlier and just now noticed. I will report back if I find a smoking gun but I have to tell you that I don't like the approach of changing things till a problem goes away since a more direct diagnosis might have been made had that approach not been used. Using a committee to solve an issue rarely works out unless the first member of the committee finds the issue right away.
Please when having electrical problems - approach the problem as something that is likely to go away instantly. Assume the issue is intermittent until proven otherwise. Only when a problem can be made to come and go under complete control is the issue then "found" and then the fix will usually be obvious. Personally I find the best tool at first is the eyes. Something has changed and often it can be found by inspection.
" ...the "crime scene" has been pretty well disturbed ... "
If the coil don't fit, you must acquit !
O.k., thought I'd give everyone an update on what the problem is, although I hate to do it because the perp was my stupidity! But first, I'd like to say thanks to John Regan and Brent Mize for their incredible help and knowledge of all things electrical. I've learned A LOT from John and will be the better for it. After much head scratching and theorizing, I finally remembered something really dumb that I did a while back. For anyone familiar with TW timers and the timing indicator he sells, the instructions say to remove the spark plugs for ease of cranking and screw indicator into #1 spark plug hole. Well, I took this literally and removed all four plugs completely, including the spark plug wires. I then proceeded to hook the red positive wire from the indicator to the battery post on the firewall and then I removed the #1 black coil timer wire from the connection at the coil box and connected the black clip from the timing indicator directly to the post on #1 at the coil box (big dummy!). I then switched the key to battery and turned the crank several times, trying to figure why the timing light was everywhere but 15 degrees past TDC on #1! I must have done this two or three times, always expecting a different result (what's the definition of insanity?) but instead I was all the while burning up my coils. When I finally re-read the instructions, I realized that I needed to hook the black clip to the wire from the timer, then I was finally able to get it exactly at 15 degrees past TDC. It sure pays to READ THE INSTRUCTIONS!
Just to confirm that the arcing across the wide gap from #4 coil to the magneto wire connection occurred because with the coil box under power and no plug wires connected the spark voltage went to the nearest source of ground which was the magneto wire connection. The spark jumped across the top of the plastic surface and also across the outside of the wood surface in the small gap that was between the wood of the coil unit and the plastic of the coil box kit material. The coils were not at fault but the carbon track on the outside surface made that wood surface a conductor and Brent Mize replaced 2 of the coils for Bill and Bill also now has a new coil box kit to install correctly since it had a few small issues that were not followed during the original installation of the kit which was done by others. Bottom line is that any time you power up a wood box coil unit you need to be aware that a spark will be generated and it will indeed arc SOMEWHERE! and that can cause future issues and can kill a coil if the arc location is hidden within the wood box coil unit itself. The carbon track was laid down at a time well prior to actual running of the car later which was of course misfiring at that location by then. I am happy that Bill reported back as to what happened so that this problem will not be repeated. Case closed.
All that damage from, less than half a dozen turns of the crank?
The issue is that with power turned on and a coil fed with continuous battery power it will buzz and the arc is like a cutting torch between the spark terminal and the magneto connection since there was no place else for the arc to go to. The coils were rebuilt and not the least bit weak. It really doesn't take too long to burn the wood which then provides an even stronger path.
Thank you John Regan for the excellent electrical explanations. You are one of the best at that. And thank you all others for good questions and more answers, as well as Bill Elliott for hanging his troubles out there for all to learn from.
One detail I think could use some additional explanation concerning the physics and chemistry involved.
Wood (in this event, the wooden case of the coil) is a decent insulator to electricity. That is why the wood was originally used for the coils, and for the board in the box that holds the four coils. But wood is NOT an excellent insulator. The chemical carbon itself is a good electrical conductor. And guess what wood is about half made out of? Carbon.
Wood, in pure, dry, form, the carbon is separated enough by other components in the wood that the wood does not want to conduct electricity. But if the voltage gets high enough, even dry wood WILL allow electricity to pass. Even a fraction of a second with a coil forced to run into no high voltage to ground will push the voltage high enough that the electricity will find some path to discharge through, even a two inch air gap. If that path is alongside wood, interesting things happen.
The spark will burn the wood, burning the wood will separate carbon from other chemicals comprising the wood, and free it to be the electrical conductor it is in its pure form. This is what we have called "carbon tracking". Often, such tracking is due to water contaminating the wood, and may be totally hidden within the wood.
One of the interesting aspects of this process, is that one minor burn releases some carbon. That makes the wood a little less resistant to electricity. That in turn allows a little more pathway which in turn reduces the resistance which in turn allows a little more electricity to pass which again releases more carbon, and. Once begun, the process often keeps building until a total failure occurs.
But this is an extreme case of carbon tracking. The spike in voltage tracked on the surface where we can see it. It is unusually large and very visible. And one burn resulted in an additional burn in the Fun Projects plastic coil-box wood replacement. This was due totally to the proximity of the plastic to the burning wood and arcing sparks (which was much hotter than the burning points of both the wood and the plastics). There was no failure on the part of the Fun Projects coil-box kit, or the coil itself.
This event and discussion illustrates very well what often happens inside coil box wood, that we usually do not get to see so well.
Drive carefully, and enjoy, W2
Very well explained Wayne. Explaining things in the simplest way possible helps all to grasp something that is foreign and thus to gain a working knowledge and 95% of fixing anything is knowing how something is supposed to work. I was lucky that very early in my career I worked at Bell Telephone Labs and had an office partner named Muerl Smith (R.I.P.) who was the most gifted teacher on the planet. He always found a simple way to make the most difficult scientific idea easier to understand. He was famous at Bell Labs for this gift yet was never employed as a teacher. I learned first hand that "Knowledge of subject does not a teacher make". Our joint office was always full of other engineers and technicians getting an explanation from Muerl on all aspects of the project our department was working one which was software development for the ESS telephone switching office. Lucky for me that he clearly missed his calling.
Thank you John R. I do try. I always look forward to your explanations of things.