Coil slosh?

[ArdWrknTrk]

What is the difference in these coils? When I converted the old 240 straight six to electronic ignition I left the old coil on it. I just now changed the coil in my ‘81 to a threaded lug unit that I asked for as a 1966 F100 spec and it runs as it did before. If it is bad for some reason I will change back.

The difference is in the ratio of primary:secondary windings.

This determines spark voltage. i.e. 20,000:100 = 13V in 26,000V spark (in a perfect world)

But, the more turns (wire length) the more primary resistance.

Points will toast from arcing if the resistance is too high.

A transistor switches faster (more dwell) and doesn't have that problem.

That's why you see "for electronic ignition only" listed on a coil with pins and not studs.

And also why a resistor is run with DSII.

Too much dwell will have the primary saturated, and then the windings become a toaster.

So, electricity -to a point- feeds the magnetic field. Beyond that point, is forced to become heat.

Heat breaks down the windings insulation, and the coil fails.

ETA: Pertronix and the like limit the dwell internally, so they can plug-and-play with older points systems.

There is no points wear or adjustment. The capacitor fires into the coil quickly eliminating overheating.

[ArdWrknTrk]

At the very least get a coil intended for electronic ignitions.

Getting one intended for points, and using it with the resistor wire in 'run' is not going to get you a strong spark.

[Gary Lewis]

Hmmm, I don’t have a spark tester Gary. I might have to pick one up. The wires are relatively new. I replaced a lot of things when I had the random stalling problem before. The pick up in the distributor is just as it was when David sent it to me. The fuel pump was also replaced around that time (trying to track down the problem) so it’s less than a year old. Not that ~that means anything with the quality of parts house replacements... but it is recent. The carb is just a JY take-off, and is on my suspect list... but the intermittent cutting in and out really seems electrical. When it died and didn’t want to restart I pulled the air cleaner and moved the throttle linkage. I had fuel jets so I moved on to checking the ignition related wires.

You can test the spark's color by pulling a plug wire and sticking an old plug in and laying it on the block. You are checking for a white or blue spark. Anything less is bad.

[Ford F834]

What is the difference in these coils? When I converted the old 240 straight six to electronic ignition I left the old coil on it. I just now changed the coil in my ‘81 to a threaded lug unit that I asked for as a 1966 F100 spec and it runs as it did before. If it is bad for some reason I will change back.

The difference is in the ratio of primary:secondary windings.

This determines spark voltage. i.e. 20,000:100 = 13V in 26,000V spark (in a perfect world)

But, the more turns (wire length) the more primary resistance.

Points will toast from arcing if the resistance is too high.

A transistor switches faster (more dwell) and doesn't have that problem.

That's why you see "for electronic ignition only" listed on a coil with pins and not studs.

And also why a resistor is run with DSII.

Too much dwell will have the primary saturated, and then the windings become a toaster.

So, electricity -to a point- feeds the magnetic field. Beyond that point, is forced to become heat.

Heat breaks down the windings insulation, and the coil fails.

ETA: Pertronix and the like limit the dwell internally, so they can plug-and-play with older points systems.

There is no points wear or adjustment. The capacitor fires into the coil quickly eliminating overheating.

Thank you for the explanation. I wish I had that knowledge before I cut the horse shoe off 😔. That’s not here or there, I will put it back and get the right coil. I know the coil isn’t my issue with three of them behaving the same. Gary I will see if I have an old plug and look at the spark tonight if I find time. I also want to check the timing and investigate if I developed any vacuum leaks.

[Gary Lewis]

Thank you for the explanation. I wish I had that knowledge before I cut the horse shoe off 😔. That’s not here or there, I will put it back and get the right coil. I know the coil isn’t my issue with three of them behaving the same. Gary I will see if I have an old plug and look at the spark tonight if I find time. I also want to check the timing and investigate if I developed any vacuum leaks.

In the dark is the perfect time to check spark. I've seen the whole engine bay look like a circus. And you might try squirting water on it to see what happens.

[85lebaront2]

You can test the spark's color by pulling a plug wire and sticking an old plug in and laying it on the block. You are checking for a white or blue spark. Anything less is bad.

The general test for a good high output system, it should easily jump a 1/4" gap with a nice hot spark.

Another point to keep in mind, the coil wire, it carries X times the load the individual plug wires do, where X = number of cylinders. It can fail internally, and the only indication is usually the spark jumping at the coil.

I used to sell a unit at my shop, the Delta Mark 10 CDI system, it was a capacitive discharge system that went on a breaker point system. These used a .040 plug gap and were very reliable. Biggest issue you had was the points building up a film of oil on them and not triggering the unit. There were updates, first a Mark 10B with a variable dwell feature to solve misfire issues on Chrysler engines, then a Mark 10C with some other improvements. The B and C models had a push button on/off switch on the main board so it could be run as a conventional points system. They had a breakerless conversion kit, but it only worked on Delco 8 cyl or V6 distributors as it needed the gap between the advance cam and pickup to be a constant distance.

[Gary Lewis]

The general test for a good high output system, it should easily jump a 1/4" gap with a nice hot spark.

Another point to keep in mind, the coil wire, it carries X times the load the individual plug wires do, where X = number of cylinders. It can fail internally, and the only indication is usually the spark jumping at the coil.

I used to sell a unit at my shop, the Delta Mark 10 CDI system, it was a capacitive discharge system that went on a breaker point system. These used a .040 plug gap and were very reliable. Biggest issue you had was the points building up a film of oil on them and not triggering the unit. There were updates, first a Mark 10B with a variable dwell feature to solve misfire issues on Chrysler engines, then a Mark 10C with some other improvements. The B and C models had a push button on/off switch on the main board so it could be run as a conventional points system. They had a breakerless conversion kit, but it only worked on Delco 8 cyl or V6 distributors as it needed the gap between the advance cam and pickup to be a constant distance.

I think I still have a Mark 10. And as you probably remember, Bill, I ran it on the '72 F250 390. You are certainly correct about the oil-on-the-points problem. Ran out of gas in the front tank and switched to the rear tank, but it didn't catch. Long story short, after disassembling the Q-Jet on the side of the road I realized that the points had fouled. Ran a piece of paper through them and off we went.

[ArdWrknTrk]

Thank you for the explanation. I wish I had that knowledge before I cut the horse shoe off 😔. That’s not here or there, I will put it back and get the right coil. I know the coil isn’t my issue with three of them behaving the same. Gary I will see if I have an old plug and look at the spark tonight if I find time. I also want to check the timing and investigate if I developed any vacuum leaks.

You can buy a ring terminal type coil meant for electronic ignitions if the horseshoe bothers you!

But a points type coil meant for a '66 is not going to work well with DSII.

[Ford F834]

You can buy a ring terminal type coil meant for electronic ignitions if the horseshoe bothers you!

But a points type coil meant for a '66 is not going to work well with DSII.

I will see if I can find one. I like that the horse shoe guards the terminals from accidental contact, but it seems like a loose janky connection for something that important.

[ArdWrknTrk]

I will see if I can find one. I like that the horse shoe guards the terminals from accidental contact, but it seems like a loose janky connection for something that important.

I think Accell sells one.

I will say that 100's of millions of DSII Ford's and AMC's have driven billions and billions of miles and the coil connector hasn't been a known weak point.