Ignition Woes

[ReadT]

Hi all,

Well I finally got my TR3 powered 1960 Morgan back on the road and am in the process of re-registering it

:G, it was running great until today. Drove it into the garage yesterday, parked it, and now it has no spark at all. Traced all the wires back to the ignition switch and starter and they look fine and are all in the right locations (no leprechaun switched them overnight). Upon trying to crank it the starter spins but there is no spark, I did notice a tiny spark jumping from the carbs to the body, on the morgan they sit about 1/16" away from each other. Thinking I may hove some grounding issues I looked around and noticed the ground to the voltage regulator was really bad off (the terminal was broken) so I replaced it and added an additional 4 gauge ground strap on the transmission bellhousing (previously the only thing grounding the engine had been a tiny 18g wire running to the voltage regulator and chassis). After doing that the starter turns over much stronger, but alas there is still no spark!

I have not messed with the distributor except to check that all the wires are connected. The coil is only about 8 months old and has less than 100 miles on it (pertronix flamethrower). The car is still a positive grounder. Didn't know if there was anything else you would suggest checking. I can't find any type of short circuit, and it was doing just fine yesterday.

Thanks for the help!

 

[DougF]

Do you also have a Pertronix electronic ignition?
If so, switch it back to points and see what happens. With all of the juice you had jumping around your engine, it could haveshorted the ignition. Pertronix are very sensitive and don't take well to shorts. I had one short between positive and negative wires, through the insulation.

 

[ReadT]

I do not. The coil is supposidly an OEM replacement.

 

[DougF]

Check the condition of the jumper wire between the coil and the distributor. The wire can break. Also make certain your rotor is good. If the arm wobbles, replace it.

 

[Deleted member 8987]

Um.....just a random thought, here......but, if you have sparks jumping from the carbs to the body while cranking, make sure you have some fire extinguishers handy, crank it at least 15 feet from any structure, and hopelikehell you don't have a stuck float.

 

[ReadT]

^ Yeah, it scared the heck out of me. Doesn't do it now that it's grounded, and I don't leave the house in that car without a fire extinguisher.

Both the high and low tension? wires running between the distributor and dizzy are fine and making good contact. The rotor has a tiny amount of play in it but it always has. Contacts in the distributor look to be in good condition.

Also I do not have a multimeter handy, I'll try to steal one from a friend later today. I assume that when cranking I should see some change in voltage running between the ignition and coil.

 

[eschneider]

Good to see another Morgan guy on the board!

Since you mentioned positive ground, I assume you have the correct pertronix unit installed, and that you have the coil polarity correct. I also assume the coil resistance is correct for the pertronix unit you are using. I'm sure you ahve that covered - but it bears repeating just in case....

In my head, the first question is: coil or distributor?

You can test the coil by:
1) make sure you have 12 volts to the "switch" side of the coil
2) connect the coil wire to a spark tester (or have a well-insulated parter hold the coil wire close to ground)
3) connect a test lead to the "breaker" side of the coil, and touch the lead momentarily to ground. The coil should create a spark every time the lead is grounded (don't hold the lead to ground for more than a moment)

Unfortunately, I don't know of a good test for the pertronix bits.

It would not surprise me if the coil/and or the pertronix is fried. With a poor ground (high resistance), current through the system increases.


BTW, As long as you are making ground straps in the engine bay, make one for the radiator as well. I usually make a 4" strap to bridge the rubber mount on one of the mounting feet.

Hope you get the old girl going. Feel free to contact me if I can help with anything at all!!!!! I would also encourage you to hook up with the DC Morgan club - there are some tarheels that are pretty active and very helpful guys. The annual meet is coming up in Staunton VA, and well worth attending.

 

[ReadT]

The pertronix is the correct unit as per Morgan Motors of New England.

1) I do have 12 volts to the switch side of the coil coming through the small wire, and power going out of the small wire to the distributor

2) Held the large coil wire near a ground and no spark at all, seems like there should be some!

Thanks for the tip on grounding the rad, I was looking at the wimpy stock rad ground today and was pondering making a larger one.

Still seems odd that the coil would have died overnight without the car running.

 

[TR3driver]

Don't just borrow one, run over to Harbor Freight and buy one!
https://www.harborfreight.com/7-function-digital-multimeter-90899.html

Not sure which one would be closest to you, but Google shows one in Raleigh
3302 Capital Boulevard, Raleigh, NC‎ - (919) 876-2023‎
and one in Charlotte
7411 East Independence Boulevard, Charlotte, NC 28227 (704) 569-0145‎
plus several more in the general area.

While you are there, I'd suggest picking up a test light, too.
https://www.harborfreight.com/circuit-tester-30779.html

Depending on the meter, you may or may not see a change while cranking the engine. The voltage jumps around pretty wildly. It's better IMO to turn the engine until the points are closed, check that there is 12v across the coil terminals; then turn until the points are open and check that the voltage goes to 0.

If that looks OK, I would probably try changing the condenser next. After that, try checking for spark directly at the coil high tension terminal instead of a plug lead. Rotors can sometimes fail while still looking perfect.

 

[ReadT]

There's no spark directly at the coil high tension terminal.

 

[eschneider]

Held the large coil wire near a ground and no spark at all, seems like there should be some!

the coil won't spark if the pertronix (or points) isn't grounding the primary windings. If you ground it manually, you can see if that puppy's gonna spark at all.

 

[ReadT]

How would I go about making sure the points are groudning the primary windings?

Thanks for the help so far!

With a multimeter:
between the (-) and (+) low tension wires on the coil there is 12ohms resistance (primary winding) between the high tension and low tension the ohmeter doesn't read anything (secondary winding). From what I read on google the secondary winding is directly responsible for delivering spark to the dizzy, so could this be faulty?

using this for reference
https://autorepair.about.com/od/troubleshooting/ss/coil-test-ohm_2.htm

 

[eschneider]

How would I go about making sure the points are groudning the primary windings?

With a pertronix unit, you can't check to see if the bits are doing their job of grounding the coil. Pertronix units are nifty critters, but this is one of their downfalls.

You can, however, check to see if the coil works by:
- disconnect the pertronix on the breaker side of the coil
- use a length of scrap wire, connect one end to the breaker side of the coil, and touch the other end to ground (12V at the switch side of the coil)
- the coil should spark each time you momentarily touch the wire to ground

between the (-) and (+) low tension wires on the coil there is 12ohms resistance (primary winding) between the high tension and low tension the ohmeter doesn't read anything (secondary winding).

12 ohms is high for the primary windings. A stock coil should be 3.5-5 ohms. These are "internally ballasted". A performance coil with an external ballast would be closer to 1.5 ohms.

resistance through the secondary windings on a stock coil is roughly 5000-7500 ohms.

From what I read on google the secondary winding is directly responsible for delivering spark to the dizzy, so could this be faulty?

could be either winding. The coil has primary windings and secondary windings. When the primary windings' "low-voltage, high current" circuit is interrupted, the magnetic field collapses and induces a "high voltage, low current" flow in the secondary windings (and through the coil wire).

Ergo, the job of the pertronix (or points) is simply to interrupt the flow of current in the primary windings. The pertronix unit does it more accurately at 3500 rpm than a set of bouncing mechanical points.

with the spare-bit-of-wire test, when you touch it to ground, you're technically charging the coil, and the spark should really happen when you remove it from ground and break the circuit.

 

[TR3driver]

With a multimeter:
between the (-) and (+) low tension wires on the coil there is 12ohms resistance (primary winding)

Did you check that it reads 0 (or at least under 1) with the leads shorted together? If so, I would say that is enough to condemn the coil.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:] between the high tension and low tension the ohmeter doesn't read anything (secondary winding). [/QUOTE]Was your meter on a range that would read 10,000 ohms? If so, that's another indication that the coil is bad.

 

[6TTR3A]

What I've seen a lot of lately is aftermarket rotors are failing.The big 3 had been selling them for quite some time (altho they have improved the quality lately)
Find an original one in your junk box or borrow one from a friends running car or get one from :
https://www.rarebits4classics.co.uk/Electrical/Rotor%20Arms.html
We troubleshot a friends TR6 at the side of the road: Tried everything.
Finally swapped out the rotor from a running helper car.
Problem now was we had two cars, one working rotor, 5 miles from Searchlight, Nevada. (Google Earth that one !!)
Frank

 

[Andrew Mace]

Bill of "Rarebits4classics" is a friend of mine, but I'm sure he wouldn't mind me mentioning that there are sources for good quality rotors in the US for those of us here. One such source is World Wide Auto Parts / NOS imports for inexpensive and (so far) high-quality and durable rotors. I've been running one for over a year now with no problems, as has a buddy with an MGA to whom I lent my spare. Now all my old Lucas used rotors are back in the glovebox waiting to save the next poor soul I see on the side of the road with one of the "bad" ones! :angel: