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Coil 101 for dummies-again

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T

Tinster

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So I replaced the rocker arm shaft, adjusted the valves and the car
started with difficulty. Ran for 15 to 20 minutes on full choke.
Shut down to cool over night.

Adjusted valves for second time, not much difference.
Car started with great difficulty and would hold idle at
1000 RPM with full choke on. Reset timing to 10* advance.
Engine ran very rough- I replaced almost broken rotor.

Next day car would not start at all-very weak spark at No1.

Charged battery overnight.

Next morning car would not start.
I could not pick up a spark from any plug wire or coil lead.

I installed all new plug wires and coil wires- car would not start
Then I installed all new .025 gap plugs-car would not start.
Then I installed new dizzy cap- car would not start.
Then I installed yet another new rotor- car would not start
Then I installed a new dizzy condenser can- car would not start.
Cleaned the points-car would not start.

I noticed I had not properly tightened down the dizzy.
From memory I tried various positions of the dizzy- car would not start.

Static timed the dizzy and let battery charge overnight.

This morning no spark from coil to dizzy. I replaced coil- car does not start.

The engine spins strongly and sounds like it wants to fire up but doesn't.
Spark from new coil to dizzy appears very weak and twitchy..

Once again please. How do I ohm test the coil to see if the coil is my problem.
Plenty of fuel-so I'm at a loss what to try next.

Thanks once again. All this from replacing the rocker arm shaft. YeeGads!!
 
Dale- Get a meter (vom) and check to see that the coil is actually getting +12v when the key is in the run position. No voltage to the coil and you will be going no-where.
 
Elliot: I have a meter.

This is what I got when I ohm tested my coil.
Could these test results explain why no fire
coming out of the coil or anywhere in the ignition
system?

Thanks,

Dale (Tinster)

ohms2.jpg
 
Dale, the exact resistances will vary with the exact coil you have. It's also difficult to measure resistances around 1 ohm or less with a common ohmmeter, which may explain why your primary resistance seems a bit on the low side. (I would expect more like 1.2 - 1.6 ohms for a coil that takes an external ballast; 2.6 - 3.3 for a coil that doesn't require a ballast.)

Check your local auto parts store to see if they offer a "universal replacement" coil for older cars. I found an Accel coil at Pep Boys for about $25 (but that has been a few years ago). If the 'universal' coil needs an external ballast and your car doesn't have one integrated in the wiring harness, then also pick up a ballast resistor (about $10).

One other ohmmeter test you can try, on the highest resistance range, check for resistance between any terminal and the can. Anything less than infinite resistance means the coil should be cleaned, then replaced.

Nice diagrams, BTW.
 
Thanks Randal: I went to Western Auto and the only coil they had for
a 1969 TR6 was the Accel Yellow Model 8140. I got 1.6 ohms exactly when I tested the terminal with a digital meter. That reading fits your external ballast required statement.

I looked up the Accel No. 8140 and it clearly stated not compatible
with 1969 TR6. Does that mean it will not work period. Or that I need to purchase an external ballast? What is an external ballast and where do you buy them?

Thanks,

dale(Tinster)
 
Tinster said:
Accel Yellow Model 8140.
Click to expand...
Yup, looks like the same one I got.

<div class="ubbcode-block"><div class="ubbcode-header">Quote:]Or that I need to purchase an external ballast? What is an external ballast and where do you buy them?[/QUOTE]You just need to add a ballast resistor to make it work. With any luck, the same Western Auto store will have them. Here's a link to one that would be suitable:
https://www.amazon.com/gp/product/B00062YZUS

Wire it in series with either one of the coil terminals ... I found it easier to put it between the coil & dizzy but it's more common to put them between the hot terminal and the harness.
 
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