[67drake]

OK-disclaimer. I hate electrical and am a dimwit when dealing with it, but forging my way through. I figured I’d post here even though this is on a friend’s ‘61 Olds Cutlass with stock points ignition, I figured the theory is the same.
Car has spark, fires, but not starting. Fresh points, plugs, condenser. Keeps fouling plugs out.
Thinking maybe I have a spark, but maybe too weak, I dug further into the ignition.
1.5 ohms on primary side of coil, that looks to be in spec.
7100 on secondary side, that appears to be a bit on the low side according to specs for a ‘61 Cutlass 215 V8
I’m showing 5.1-5.2 volts at positive side of coil with key in the run position. I read that it should be 7-9, and that 5 could cause a weak spark.
I don’t have his shop manual in front of me, and he’s out of town, so I’m relying on the internet for these specs. BTW.
I don’t want to throw parts and money at it, so just wondering if these readings are far off enough to cause a spark but no start condition?
Also, can I temporarily hook 12 volts to the positive side to see if it runs, or will the points burn up that fast?
Thanks

[george kujanski]

Go ahead and connect bat voltage to the coil
It can run for a bit
That's what actually happens during a normal start cycle.

[Bill Hanlon]

I agree with George that full voltage won't hurt as a test.

I agree with you that the 5 or so volts on the + side of the coil with the key on, the engine not running and the points closed is way low. Should be closer to 8.5 volts.

Is the coil stock?

If the back side of the ignition switch is reachable with one lead of your ohmmeter, you have 10' or so of scrap wire and you have a helper....
Turn the key off.
Remove wire from coil+ and connect one lead of ohmmeter to the removed wire.
Connect one end of the 10' of wire to the other ohmmeter lead.
Touch the other end of the 10' wire to the #1 terminal of the ignition switch (has the 2 yellow wires) and read the ohms value on the meter.
What does it read?

By the way, here is the wiring diagram I'm using. Got it from https://www.oldcarmanualproject.com/...re5765-280.jpg

[67drake]

Thanks guys!
I’ll have to see how easy it is to get at the ignition switch tomorrow.
I would guess it’s the original coil, it looks ancient. The car is pretty much bone stock 215 V8.
Any opinion on the 7100 ohms on the secondary side?

[Bill Hanlon]

If the switch has a plug wiring connector just pop it off to do the test.

You say 7100 ohms on the secondary is below spec for a 61 Cutlass. What does the spec say? I can't find it.

[67drake]

Originally Posted by Bill Hanlon

If the switch has a plug wiring connector just pop it off to do the test.

You say 7100 ohms on the secondary is below spec for a 61 Cutlass. What does the spec say? I can't find it.

Just going by AI because I don’t have his shop manual, it says 8-12,000 ohms

[Bill Hanlon]

All this is assuming a battery voltage of 12.7 volts DC.

If the AI response is right about the primary resistance of the coil (at an average of 1.42 ohms) and the "1.35 ohm ballast resistance wire", then the voltage at the coil+ with the key on, engine not running and points closed would be 6.50 volts.

In order for coil+ to read 5.2 volts that you are seeing with a coil primary resistance of 1.5 ohms the resistance wire would need to be 1.02 ohms instead of AI's 1.35 ohms.

[Schurkey]

Originally Posted by 67drake

‘61 Olds Cutlass with stock points ignition

Originally Posted by 67drake

Car has spark, fires, but not starting. Fresh points, plugs, condenser. Keeps fouling plugs out.
Thinking maybe I have a spark, but maybe too weak, I dug further into the ignition.
1.5 ohms on primary side of coil, that looks to be in spec.
7100 on secondary side, that appears to be a bit on the low side according to specs for a ‘61 Cutlass 215 V8

What is the resistance from primary windings to ground? Should be "Infinite" resistance--OPEN CIRCUIT, NO CONTINUITY.

AFTER your coil has passed all three resistance checks, it may still be defective. The only way for a typical D-I-Y to know if the coil is good is to get the coil appropriately warm, mist it with water from a squirt-bottle, and see if it will still reliably throw a spark across a spark-tester calibrated for ballast-resistor style ignition. There are multiple designs and even more vendors, but this is my favorite kind:
Pay ZERO attention to the "small engines" claims.
http://www.amazon.com/dp/B001OK6MIO/...=2VLYZKC3HBBDO

DO NOT BUY any "spark tester" where the spark makes a light-bulb glow. You want one where you can SEE the spark jump an actual, calibrated gap.

Originally Posted by 67drake

I’m showing 5.1-5.2 volts at positive side of coil with key in the run position. I read that it should be 7-9, and that 5 could cause a weak spark.

Points OPEN, or points CLOSED? Kinda guessing the points are closed, and your readings are approximately normal.

What is the battery voltage with no load? Should be about 12.6--12.8 depending on battery construction and temperature. 12.5 is 1/4 discharged. 12.0 is near-dead.

[Kenth]

From the 1961 Olds F85 Service Manual: