Ignition Coil Specs

How much resistance should the windings of the ignition coil on my '86 PCM 351 have?

Maybe I missed it, but I didn't see any specs for primary and secondary winding resistance... That's what I need! I just want to check that my coil is functioning properly. It's the oem coil attached to the oem points setup. I'm not getting good fire in the distributor. I suspect my batteries are a little low, but while they charge I just wanted to double check everything.

My primary = 1.8 ohms and secondary = 6.61 ohms

I'm running an Echlin Icr23 ballast resistor, so it is 1.3ohms, but I'm just measuring the windings, so the resistor isn't in the circuit....

Chris,
I think the primary and secondary windings in a coil share the same negative terminal?

sorry boys they are two seperate windings inside of each other with a ferite(sp) core. the primary winding is energized and induction transfer's the charge to the secondary winding and to the plug. There is no physical connection betwwen the two. I'll have to do some checking as this may not be true for a cannister style coil, it's been a long time since those days, it is true for a HEI or coil for a Direct ignition system.

Chris, you have sparked my intrest on this one.
How do they acheive the same funtion with a different wiring connection? Induction is the MAGIC that happens, explain ?
Can you teach an old dog some new tricks?

I don't know about that Doc but here's my BS.

On a modern coil like what is used for a HEI dist. and on a DIS system you have a primary winding, and a secondary winding. The primary uses larger gauge wire and less turns for the coil compared to the secondary so I think we used 14-18 gauge on the primary side and like 41-43 gauge wire in the secondary side of the coil. these two coils are then place inside of one another primary being inside, secondary being outside and then a metal core is placed thru the center of the primary and then around the outside of the secondary, typically refered to as an E-lam as that is the shape of part of metal core which is a series of lam steel stacked up to a set thickness and welded together. The other section of the lamination for the metal core is the I-lam which is welded to the e-lam and creates a gap between the center section of the lamination. The welds are real easy to see on an HEI coil what isn't is the gap, but it's the same basic configuration hei or dis.

The primary winding is energzed by 12V's this builds a magnetic field in that coil, the coil colapes transfering the energy through the metal core to the secondary winding which in turn because of the finer gauge wire and additional turns of wire like 100:1 to 400:1 ratio's multiplys the current to an order of 40-50 Kv resulting in the spark at the plug. I believe on the HEI and a canister coil the windings share a common ground so that the plug fires but, on the DIS they do not and the ground is achieveg through the other plug attached to the coil pack, because one cylinder is under compression which, and don't ask me how, drops the resistance and fires that cylinder. clear as mud?

Thanks, Hollywood! I just discovered that my new fluke 88v throws a little "K" on the screen instead of moving the decimal... There is no telling how long it would have taken me to notice that if I wasn't looking for it.

I went out this morning to see if the battery charge solved my problem. I left the multimeter in the house, but by watching the spark I could tell it was still weak. There was no ignition taking place while turning the engine over either. I bypassed the ballast resistor (which should be happening in the solenoid anyway) and instantly got a strong spark. She fired up, I removed my jumper wire, and the engine continued to run smoothly. I switched it off and tried again. The coil is now throwing a strong spark every time... Why would it behave like this? Every connection is sparkling clean and tight! It's like the coil just needed some time to build up its strength.   

The ballast resistor is only about 6 months old. The coil requires an external resistor (it is the original coil). If I remember correctly, I replaced the condenser in 2005, but I'm checking the spark at the coil not at the plugs, so the condenser doesn't fit into the equation.

Please educate me.

For peace of mind, I just tested the condenser and it is functioning properly ;)

79nautique wrote: So when you win the 500 with your ignition let me know so we'll have something in common to talk about.

Andrews just looking for some help troubleshooting his problem. Lets not go backwards here Chris.

Andrew,
What Ohm readings are you getting off the coil. Did you ever locate the exact specs?

OK step by step

Verify you have atleast 9v at the coil with key on.

next get it started use the jumper again if needed.

Set the dwell

Set timing

Adjust carb as needed.


if the dwelll isn't right then your not going to get a good spark without extra juice to the coil. So if you can't get it started then use a feller gauge and get the dwell close then refine that setting once it's started so that it's at 20 degress set timing at 6-8 degrees.

d*cking with the resistance is a waiste of time the coils either good or it's not end of story the points are either good or not same with the condensor.

So if you have the correct voltage at teh coil, the dwell is set correctly and the timing is set correctly and it's not working properly then you have bad parts somewhere within the ignition system

BTW INDIANAPOLIS 500 MEMORIAL WEEK-END RING A BELL?

BTW the spark should jump atleast a half inch.

Andrew,
I don't know about the green eyes but Chris does sort of have blond hair! Right is Chris and left is Billy (boatdr).



pbrainard@wistool.com