While troubleshooting a starting problem on a 27 Tudor we discovered a strange scenario that has us puzzled. With plugs removed, when #3 coil buzzes we get a slight spark on #2 & #4 also.
Here is the situation:
Coil box has been rebuilt using Fun Projects Kit
Coils rebuilt by RP
Coil box clean & dry no debris in the coil box
Wiring harness disconnected- ground to each coil individually provided by a jumper wire from ground to the coils grounding connection on the box- thus eliminating the harness
We swapped coils from #1 & #3- no change.
Is this a normal situation where the spark is jumping by static or some other cause?
If it is not normal what steps should be taken to eliminate the bleedover?
Clean your timer and check for a short in the wiring harness from coil box to timer. What timer do you have?
That is interesting, with the harness removed you are getting a bleed. Try cleaning the inside and outside of the box with denatured or rubbing alcohol. You may be getting just enough current on the outside, or inside of the box to get the adjacent coils to activate due to contamination/dirt.
Mark- as stated, the wiring harness and timer are disconnected. WE are grounding the coil box manually.
Can you provide some photos of yer plug wires and coilbox interior and exterior Bill?
Ok I read it as you disconnected the harness after you were getting the cross fire. Guess that points to coil box or timer.
Shouldn't be buzzing those coils without a current path through the plug wires. Good way to burn out the secondary winding of the coil.
Your "cross" connection may be coming from the coil box lid via the coil unit "hold down" spring clamps that can easily get bent and interfere with normal coil point operation and perhaps allow some arcing to occur. This is something that is unique to the 26/27 coil box. Just a guess. As others have stated, please post a picture of your rebuilt coil box and lid and perhaps we can see something you might not be noticing.
AS long as there is a path to ground via the spark plug and for the short time the test is being done should be ho harm done to coils. I think he means the the plugs are lying on the engine with the spark plug wires connected.
The SLIGHTEST amount of conductive contamination in the timer will cause a coil to whisper.
Been there.......done that.
As I read it. Bill R has pretty well eliminated the timer and any possible wiring harness issues. The Fun Projects coil box kit pretty much eliminates any usual coil box carbon tracks or other common high resistance shorts (I suppose someone could manage some sort of short there, but I really don't see any likely way it could happen).
Like John Regan, I also have seen a high voltage carry through the steel cover. Are you testing with the cover off?
Also, especially with the short connections of the '26/'27 coil box, make certain that the spark plug wire end is not angled or bent too close to the narrow steel bar that helps hold the side ends of the box in place.
Something else that I have seen, is cross firing through the spark plug wires themselves. About ten years ago, a whole lot of the colored cloth spark plug wires sold for antique automobile use was not adequately insulated. Ever looked under the hood of a big Pierce Arrow six cylinder with dual ignition wiring looms about four feet long? The car was not running quite right, and when it was looked at in a dark shop? It was a light show from the front of the motor to the back of the motor. The wiring was all new, and cross fired.
Something that can contribute to that when working on a car, is pulling the plugs out and laying them on the engine head to view the firing. The ground connection of the base of the plug lying on dirt, corrosion, rust, or paint is problematical at best. If number three is sitting on a better spot of paint (resisting ground), and two and four are leaning nicely on a good spot? Minor cross fire leakage will probably show up.
The best way to avoid this problem, is to remove all four plugs from the head, but leave them on the plug wires. Use some good copper wire to twist tie around the base of each plug individually and electrically tie them all together for a common ground. A manifold clamp bolt/nut can make a good ground, and again, ground all four plugs to one point.
If you want, try each coil individually with all the spark plug wires bunched together. A serious cross fire could still show up, but minor cross leakage should not. Then separate all the spark plug wires with a full half inch or more of air gap the full length of every wire (still keep the grounds together). Again, check each plug at the spark gap.
One of my favorite diagnostic tricks is to look under the hood in the dark at night with the engine running. Have a flashlight in your hand so that you can turn it on to see where you are putting your face and hands, but watch the wiring with the engine running and lights out. Be careful of everything including voltage and the fan and belts. If there is any cross leakage of the high voltage, you should be able to see it easily. Sometimes, you can even spot low voltage shorts. Pay particular attention to the spark plug porcelain, especially near the base. Defective porcelain can often arc through flaws in the porcelain and will usually glow a little in the dark. This type of miss-firing usually will not lead to cross firing on another cylinder, but often leads to a rough running engine.
Good luck! And let us know what you do find.
Drive carefully, and enjoy, W2
John, I forgot to list that the coil box lid was removed in order to eliminate a short that could be created by the hold-down pieces.
And, as stated - the harness is disconnected which in turn disconnects the timer.
I would like to clarify something about this spark. I described the spark as "slight" which is exactly what it is. The spark does not "jump" like we are accustomed to, rather when I saw the faint spark I had to get 2 second opinions as to whether or not my eyes were playing tricks.
The spark is very faint and only appears if the distance between the plug wire & chrome head bolt is approx .005" or less.
That is why I referred to the possibility of "static".
This is a reach but stranger things have happened;
If you are getting bleed on 2 and 4 when 3 is JUMPED from the coil box to the terminal on the timer maybe you are getting something like the Tesla Coil effect.
Could be the atmospheric conditions are allowing the discharge across the plastic used to make the terminal holders for the coil box. As 2 and 4 terminals are on ether side of 3 could be that there is just enough power to reach those two. If the coil box is clean try wiping it out with a dryer sheet.
or Jacob's ladder spark gap;
Same thing, wipe with dryer sheet.
(Message edited by redmodelt on August 10, 2015)
The box is isolated from the system, re-built and uncovered. High voltage is like love. It'll find a way. Is it possible a porcelan insulator is taking a dive/shorting?
There's also the old "check it in the dark" trick.
1926-27 don't have the porcelain tubes. The coil box not isolated as it's bolted to the head. The wires from the coil box to spark plugs don't cross if the correct set are installed so there should be cross firing from bad wires touching.
While doing some maintenance with the spark plugs lying on the head he noted that WHEN No 3 fired so did 2 and 4.
The harness was removed, guessing the coil box end. When a jumper wire was used to fire No 3 he was still getting cross fire on 2 and 4. Jumping it in that manner there would be no way to fire 2 and 4 even if there was a short or contaminates in the timer.
This could be an isolated incident that may not even come into play when the car is running. Could it be that the longer continuous firing time when checking is creating a static charge on the plastic and the path to No 3/ground is not good enough to handle all the discharge so bleeds over to 2/4 which are on ether side.
"isolated from the system". The ground wires are disconnected.
I think the problem has been found. After finding the phantom sparking on my son's T, I decided to check a couple of mine at home. Both had the same phantom sparks that can only be seen in poor light and there is a common thread in all 3 cars. Years ago, we read about making plug wires from barbed-wire and since we have both been accused of being a bit redneck we made a set for our TT and they worked fine with no bad affects unless one of the wires gets accidentally touched. At that point the real redneck comes out of us.
So, I am accepting the fact that since there is no insulation on the wires, some of the charge travels through the air to the next barbed wire.
Since we both like redneck stuff, and since the leakage has had no ill-effects for almost 20 years.... the plug wires are staying.
Hey, we've seen dead carps mounted on fenders, tow ropes attached to the spare tire carrier, under-drawers plugging rusty holes, a chicken sitting in the back seat and/or hanging from under the car, G-STRING panties hung between a headlight and the motor crank to stop the rattle , so what the heck! The barbed wires stay!
I would be disappointed if the barbed wire were ever replaced. I have some of the highly sought after "rusty barbed wire" available to me on the fence row behind me. That's what I used on the TT I used to own. Might have to make a new (rusty) set for the 27.
See. I'm not the only redneck on the forum.
Gary- when you pull into a service station for gas folks no longer ask "how many miles per gallon do you get?". Now they give a puzzled look and ask "barbed-wire?".
Yup. I used to take the "possum wagon" to the local car shows. I wished I had a dollar for every time somebody said, "It can't run like that, that's just for show".
One summer the possum wagon lived at Ken Swans house as he wanted it for the Selmer car show. I took it over in June and didn't bother to bring it home for a few months. I'm sure Ken got asked about the barbed wire over and over.
I had a friend in Michigan (Carl Davis - deceased) who also ran barbed wire on his TT.
I might make up an extra set for the Christmas Party gift exchange. Should be highly sought after!
Methinks that a real redneck wouldn't have brass ends on the barbed spark plug wires.
That is a common misconception of southern Rednecks. A true Redneck will put forth a great deal of effort into coming up with something like that and take pride in his creation because it is almost as good as "store bought".
You have confused the true southern Redneck with the more common Hillbilly (found worldwide). Even then, a true Hillbilly would have just stole another car rather than fix what he has!
Ken, would alligator clips look better?