Anemic spark - Bad coil?

[Jim Lee]

First, Happy Thanksgiving to one and all. After you celebrate Thanksgiving with family and friends please ponder this.

I think I am finding out why it takes forever to start my TR3 even while spraying starting fluid into the carbs while turning it over hoping the battery and starter hang in there. Plenty of fuel. I am becoming it is an ignition spark problem as I finally removed the number 1 wire and put
a spare plug in there and layed it on the valve cover. There is a spark but it is a very anemic looking spark to me. I am no expert on healthy sparks but this looks like it is barely making the gap. No pop...no sizzle to say the least. So I have done some swapping with the ignition system. New condenser, tried three different coils all of which have worked at on time or another and as far as I know should be working now. Changed points. Set gap and reset it. Dwell is 49 degrees which sounds close to me. I have taken apart the distrib to clean up the advance weights and springs. Put it back together being as careful as I can be with the wire connections. Ground wire in distrib given extra attention. Here is my first question, finally, if you look at the jpg file I have attached you see both the red wire coming from the coil and the black wire from the condenser connected together at the top of the points post. I am wondering if they should be seperated in that one should be at the top of the post (but underneath the plastic
deal) and the other below, on top of the other plastic thing. Why else would they go to so much trouble by putting
those plastic things at the top and the bottom?

The other thing that puzzles me is that I cannot measure ANY
resistance between the postive and negative posts of ANY of my three coils. It measures 0 on all. I thought it was supposed to measure either 1.5 or 3 ohms. I vaguely recall
fooling around with my motorcycles coils and measuring something as resistance. Could I have 3 bad coils? If I do
could I have something messed up on the car that fryed all three that I ought to hunt around for? It is hard to believe that all three are bad but it is clear that all three measure absolutely 0 resistance. I don't know whether this is here or there but if I measure from one post, either
positive or negative, to the center where the big wire goes to the top of the distrib, I do get resistance. 9.9, 7.1 and 8.7 ohms for each one.

I would love to just by a coil and have a big healthy, snappy spark but I am really wondering if I have a coil killing machine right now and would be just throwing away another $20. Last kind of interesting fact is that I can start up and run my black beauty but only after three and sometimes four rounds of starting fluid squirts into the carbs, with or without the air filters. Each failed round runs exactly as long as the starting fluid does. Then finally it will run by itself and I can ride around. It runs pretty well too except under load. Huge bog and sometimes backfiring. The bog on acceleratioin I can pretty much count on. Last bit of information. My charging system
is not charging. I plan to take care of that by doing an alternator conversion tomorrow. For now I am charging the battery every night. It charges up to 14.5 volts....so far.

Thanks very much and have a Happy Turkey Day.

Jim Lee

 

[Jim Lee]

I am having a hard time getting my jpg file attached.
Let me try this again

 

[Andrew Mace]

Several questions come to mind:

1. Does this problem occur every time you start the car cold or warm? just cold? or is it only after the car has sat for several days?

2. Once running and warmed up, how does the car perform?

3. What kind of spark plug wires do you have, and on what type of cap? I've heard from several sources that wires other than solid wire core type don't "mesh" well with the regular side-entry (pinch screw inside) caps. They might work ok initially but not so well after a number of months.

 

[Geo Hahn]

You should be able to measure resistance across the coils, more than 3 ohms... but of course they need to be disconnected whilst you take that reading.

Ditto on Andy's comment on wires... from your photo looks like you have a modern set with noise supression & the black conductor. I only use copper core. Get a 'universal' set for a V-8 and you'll have enough to make 4 or 5 TR sets. Not so good for radio reception but who cares?

Those wires you asked about should be fine as you described them, no need to separate. I guess that red wire is in place of the black wire that would have been there originally. It loks a bit strained in your photo.

 

[Jim Lee]

"1. Does this problem occur every time you start the car cold or warm? just cold? or is it only after the car has sat for several days?"

Every time I start the car cold.

"2. Once running and warmed up, how does the car perform?"

It idles beautifully. Very steady very little fluctuation.
The first thing you notice driving though is a serious bog under load. For example to make a normal 90 degree turn from one road to another you would have to keep the revs high to not bog on the other side of the turn.

"3. What kind of spark plug wires do you have, and on what type of cap? I've heard from several sources that wires other than solid wire core type don't "mesh" well with the regular side-entry (pinch screw inside) caps. They might work ok initially but not so well after a number of months."

The wires are just generic from the local auto store. How do you distinguish solid wire core type wires? The wires are not old, especially in terms of mileage. I do have a distrib pinch screw cap where you stick the wire in and pierce it with that tiny screw. Also that reminds me that I have run the car in the dark and looked carefully for cross firing ignition wires and/or anykind of electric leak around the distributor.

Thanks very much,
Jim Lee

 

[Jim Lee]

"from your photo looks like you have a modern set with noise supression & the black conductor. I only use copper core."

So I could ask for 'copper core' and 'solid core' wires at the auto parts store?

Isn't having three coils that do not measure any resistance except from one post to the center seem strange? The VOM is working. I do not get that at all.

Thanks,
Jim Lee

 

[piman]

Hello Jim,

I suspect that your meter is innacurate (or on too high a range?) as zero ohms at the coil will take a lot of current and do the points no good at all. Another check you can do is to measure the voltage at the distributor side of the coil to earth with the points closed and open. The former should be in the range of 0.2 to 0.4 volts and the latter should give battery voltage.
I personally do not believe your problem is with the HT cables. (I do use copper core HT cables myself but that is for reliability)
Normally the only thing that destroys coils is using something like a ballasted coil on an unballasted system which I believe the TR3 is. I would double check your condenser connection and if correct try another new one.
The condenser is essential in getting a strong spark, and is connect in parallel across the points, which looks to be how you have it.
One other check you can do is to take the HT lead from the coil and check that to earth to see if you have a good spark. This checks for faulty rotor arm, distributor cap etc. If the spark is good at the coil then ther must be some HT leakage further on.

Alec

 

[smcmanus]

Try switching the post wires on the coil. Is the coil housing properly grounded?
Good Luck
/ubbthreads/images/graemlins/cheers.gif
Steve

 

[69tr]

Have you checked the timing. I have found in the past that a bad coil will usually fail when it is hot more so than when it is cold.

I would be careful with the starting fluid. I causes the ignition in the cylinder to be so hot that it could damage the engine. This was drilled into me by several engine mechanics. They recomend using carb cleaner if you must use something. I don't know if that is any better.

Pete

 

[YankeeTR]

Make sure you have a properly charged battery in GOOD condition. I've seen cars that had hard start problems and owners who literally threw $$$ at them without results only to have a battery without enough reserve capacity to provide enough electricity to start the engine.

Check for a frayed or broken wire in the distributor. My '49 Ford F-1 pick-up with Buick Nailhead power gave me fits for a year..it would just stop running...then I found a frayed low tension lead wire inside the distributor.
The bad wire had fried three condensors in a year before I found the problem.

 

[Geo Hahn]

[ QUOTE ]
...So I could ask for 'copper core' and 'solid core' wires at the auto parts store?...

[/ QUOTE ]

Ask for metallic, not conductive silicone core.

If you go to CarQuest I think the p/n is 3802.

Even if this isn't your 'current' problem I think it will save you grief down the road.

 

[tomshobby]

Have you checked the voltage across the coil. When starter is turning and while running? The coil can not put out more than it takes in.

 

[JeffS]

You should retest your spark. Cut the electrode off of your spare spark plug. If your coil and wires are in good condition, the spark will jump the gap. If not, replace the plug wires with copper or mag core wires such as Bosch or the mag wires that Moss sells. You can test the resistance inthe wires from the cap terminal to the plug boot- a mag wire will give around 0 Ohms, while a resitance type will be anywhere from 1K to 10K Ohms.

Your dwell should be 60 degrees - 49 is too low!

 

[Simon TR4a]

As a test for weak spark you could try reducing the plug gaps to about 15 thou. and see if the car will start more easily, as the spark will jump ther small gap readily. (This is just for diagnosis, I would not drive around too much like this.)

The other test you could try is take out a plug and ground it to the block, then get someone to turn the key while you observe the colour of the spark, which gives you a clue to how strong it is.
The old rhyme goes" If its white, its right
If its blue it will do
If its red, your dead!"
Simon.

 

[Jim Lee]

Ok. I must be just about to learn some incredible lesson on ignition. Remember before I had a weak spark? Now I have no spark. NadaI and nothing. I got all excited that I had found my ignition problem when I noticed that the graphite stem that is inside the center of the distrib and makes contact with the rotor button was not extending as far down as the other two rotor caps that I have. As if the spring had collapsed or just wasn't working. In any case it was obviously not hanging down as far as the other two caps. So
I am thinking I have this thing licked. The high tension charge is not getting to the rotor button and therefore giving a very weak spark at the plugs. Case solved....I thought. Today I put the other cap on, a lucas cap, and now
I get no spark at all. Put a plug on the coil wire and absolutely nothing. Now here is my big question. I think that I remember measuring battery voltage at both the 'in'
negative side of the coil and the 'out' (to distrib) positive side WITH the ignition switch on. 12+ vol at both sides of the coil that I could trace all the way to the contact point. Now I measure the full battery voltage at the negative post of the coil (from the battery) but .03-.04
volts on the other positive side that goes to the distributor. I have three, count 'em, three coils that I have tried, stealing one from my running 1963 Ford Thunderbird and all act the same. None measure resistance
from post to post, all measure resistance from center to either posts. Normal resistance. All work, or more accurately do not work, in the same way on the TR. I would be glad to buy another coil tomorrow but I have very hard time believing that I have three bad coils though I suppose that stranger things have happened.

So, while I feel good that this is definitely a no spark/ignition problem I have no confidence at all in a new
coil fixing it...but at the same time I cannot think of or
imagine any other part presenting a problem. I have used
two different good sets of points and checked and rewired all inside the distributor. I have three good rotors that
I switch around and also three condensers one of which is brand new. I mentioned the three dist caps before. The battery is fully charged. The engine ground cable is well connected to the frame.

Any ideas or thoughts more than welcome.

Thanks very much,
Jim Lee

 

[piman]

Hello Jim,

I think you are getting in a muddle somehow. Firstly things like the spring tension on the cap are not too important, remember the rotor does not touch the poles inside the cap (or should not) and the HT jumps the gap. Don't think of it like normal low voltage, Similarly high or low resistance leads make no difference. Until the spark jumps the gap you will have full HT voltage at the end of the cable, no current, no volt drop.

Please go back and ensure that the voltage at the coil terminals are as I said in my first post. Points open = 12 V, points closed = 0.2 - 0.4. If both are correct then the points are OK. Now double check your gap or dwell; dwell, especially can be in degrees or percentage so be sure what the spec is and what you are looking at, i.e if the spec is degrees, and dwell meter reads percentage, that will throw it way off. Check the spark at the coil post with a HT lead to the body, if it is still weak and the check outlined are right then it is either the coil or the condensor.
By the way the correct coil polarity is negative terminal to the distributor for a negative earth car and vice versa. Wrong polarity, however, makes no difference to coil voltage, but affects the ability of the plugs to fire, i.e. they need a higher voltage for a good spark, confusing?
Alec

 

[mikespain]

Just a few thoughts-are you sure the coils are positive earth coils? with no spark, disconnect the feed to the coil and check you've got 12volts going in-reconnect and disconnect the wire going to the dizzy check youve got voltage coming out of the coil-reconnect and check voltage at the points with the points OPEN.Check that the insulation washers are in good condition where the condenser and coil wire are bolted to the points-any contactof these wires with the center post will stop it firing.also check the insulation as the coil wire comes through the dizzy body and that the internal conection isn't touching the body of the dizzy.if all checks out ok with the high tension lead connected to the coil and held 1mm away from an earth(or spark plug conected and grounded)with ignition on and with the points fully closed when you open the points with an INSULATED screw driver you should get a spark(make sure you dont bridge the points with the screwdriver or spin the engine over on the key.I agree that dwell of 49 is way too little -that alone will give you a weak spark-should be 56-60.Don't forget to reset your timing afterwards aswell.Your original problem sounds like fuel as it starts and runs so long as you squirt starter fluid in,if there is fuel there then all your doing really is giving it a richer mixture,are you chokes working ok?

 

[smcmanus]

12V at the coil? 63 Ferd T-bird coil? Yes, you have fried the coil. Use a VW 12V internal ballast coil or use a standard coil with a ballast resistor between the + terminal and the ignition switch. You should then be getting 6 or 8 V at the coil. OK, was this car originally 12V negative ground? As mentioned above, the "polarity" is important to spark strength. So if it is negative ground, + coil to power and - to distributor. You are very close to fixing the problem, don't give up now!

Have a nice day
Steve

 

[piman]

Hello steve,

a TR3 doesn't use a ballasted coil system. It should have 12 volts at the coil.

Alec

 

[Keoke]

Hi PiMan , what is this Positive Earth coil bit I be hearing about?---Keoke- /ubbthreads/images/graemlins/grin.gif