Questions and maybe a rant about the new coil points

[Mark Gregush]

Ok so new wisdom is .010 to .012 cushion spring gap, but the new points are like .017. The old KW point, the upset behind the rivet is about 1/8"+ to center of the rivet, the new ones, it touches the rolled over edge of the limiting rivet and is about 1/6" to rivet center. Our club has a set of the setting pliers but don't think they will work on these. I made a cupped tool to put in the vice, but it not an easy job to hold the points, punch and hammer at the same time! LOL
Someone in the past suggested cutting a slot in a .010 feeler gauge to use as a stop that would be put between the cushion spring and bridge. I do have a nice piece of flat stock to work on and think that might be a good way to go.
Question; When setting the point gap, is the gap measured with the cushion spring against the bridge or hanging down? Do not recall ever reading or seeing anything about this. If hanging down, I am in big do-do as there are no thread left on some of the studs and some of the lock nuts are proud of the stud and to get the .030-,031 gap, will have to address the cushion rivets.
With the cushion as is, I end up with about a .013 gap when the points are open. I have all 8 coils set to approx 1.3 amperes with no double sparks on the HCCT. But....will if I have too, just hate to mess up new points.

[Mark Gregush]

First try with the shim stock and slot, no movement.

[Original Smith]

I have several sets of NOS Ford points, and the gap on them isn't anything as much as what is being made today.

[Mark Gregush]

Guess if you have all 4 coils with the same points and gaps you would be fine re each dwell or firing at close to the same time, but might have to re-time the engine if the coils are replacing the old ones with old style points.
If you installed one or 2 coils with the new gaps with coils that have the old gaps/points (.005 cushion spring travel), you would have different dwell/firing times now. The new points, the lower bridge would have to travel about (if I leave them as is) .017+/- before the points open, the old points only maybe .005+/-. Even if I got them to the new suggested max of .012, could still be a mix of firing times if mixed with old style.
Guess the way around that is to tell the person(s) that if they need to replace one coil, need to replace the other 3 so all 4 are the same.
Never really thought about it much till reading the posting on the Anderson timer and inter-cylinder firing and when installing these new point seeing the huge gap.
In this case, the guy that I am doing the spares for, I have done many coils over the years. Just because he has these new ones does not mean they will be installed as a group. In other cases, maybe someone only needs one coil/points replaced. They would now have one coil different then the others.
Maybe I am or maybe I am not, over thinking this. Don't know?

[MKossor]

Ok so new wisdom is .010 to .012 cushion spring gap, but the new points are like .017.

Where the heck did this "new wisdom" come from? The Ford specification is 0.005" which agrees very well with the measured test data I took using a set of points with adjustable cushion spring travel.

Note that there is no significant change in coil firing time or firing current of THE First Spark once the cushion spring travel reaches 0.006" That means the point contacts have opened after 0.006" travel even if there is more available travel before the cushion spring hits the limit rivet stop. In other words, the vibrator spring contact separates from the cushion spring contact (Contact OPEN) all by itself after 0.006" of cushion spring travel without the help or benefit of the limit rivet stop. This is a critical detail many do not understand the consequence. Coil points with excess cushion spring travel (More than the 0.005" Ford recommended) The point contacts separate without the help or benefit of the limit rivet stop often do so relatively slowly, negating the purpose of the capacitor (condenser) promoting the formation of an arc. Coil point arcing is undesirable for several reasons.

1. Point arcing causes premature wear of the electrical contacts.
2. The arc continues primary coil current flow but at decreasing value which weakens the eventual spark resulting in poor combustion.
3. The arc delays the spark which retards the ignition timing.
4. Point arcing is NOT apparent from Average HCCT coil current readings

The arcing is random in occurrence and duration which means the spark delay is also variable based on the coil point physical characteristics (point gap, cushion spring tension and vibrator spring tension) which produces ignition timing variation that diminishes engine power and introduces engine vibration. Now, it is entirely possible to adjust these 3 variables with the balance necessary for the coil to fire spark with equal and consistent firing time with excessive cushion spring travel IF you have a means of measuring coil firing time and consistency. It just may take a while to find the right balance and may drift off that balance much easier over time. I have personally adjusted coils with 0.020" cushion spring travel for equal and consistent firing time in 5 minutes where as others with similar cushion spring travel required over 1 hour!

Ford knew what he was doing by specifying cushion spring travel of 0.005". The primary coil current is already of sufficient amplitude to guarantee a good hot spark with sufficient energy to insure combustion after 0.005" travel of coil point contacts closed. Both point contacts are traveling with considerable momentum after 0.005" cushion spring travel. The cushion spring contact stops abruptly when the cushion spring hits the limit rivet permitting the vibrator spring contact to continue moving, away from the cushion spring contact VERY Quickly. The capacitor (condenser) permits primary coil current to continue flowing for a short period of time (millionths of a second) but that is long enough for the point contacts to move physically apart from one another with the cushion spring contact abruptly stopped by the limit rivet. Abrupt physical separation afforded by the limit rivet and brief continuation of primary coil current by the 0.47uF capacitor is key to preventing electrons from jumping the point gap and forming an arc. This also hastens the collapse of the magnetic field once the primary coil current ceases to flow through the capacitor. This results in a higher secondary voltage to be produced creating conditions necessary for the spark plug to generate spark.

Coil points with excessive cushion spring travel are common due to lax controls during manufacture. It is possible to reduce cushion spring travel by crimping the limit rivet in a controlled way. Mike Vaughn published a method of reducing cushion spring travel in the Jan-Feb 2018 issue of the Vintage Ford magazine. Be careful not to over crimp the limit rivet or the points will be rendered useless.

The cushion spring tension must still be adjusted for proper tension even with 0.005" of travel. Too little cushion spring tension OR too much cushion spring tension will result in the vibrator spring contact pulling away from the cushion spring contact pre-maturely then quickly closing again to produce the dreaded double spark; a dreaded condition because it produces a weak spark earlier then desired followed by a second weak spark occurring later than desired relative to piston position. Poor engine performance results from insufficient spark energy delivered at the wrong time.

Folks who adjust their coils for equal and consistent Firing TIME (better than 90%) know the remarkable difference it makes in engine performance. There is a huge difference between a Model T engine that "Runs" and one that Runs Well. Maintaining that level of coil performance requires periodic adjustment measured in months Not years. Be weary of comments otherwise from folks who never experienced the difference because they don't know what they don't know.

[Hal]

Mike,

Could you please clarify your phrase "(better than 90%)"?

I'm not sure what you are saying there. Are you saying that better than 90% of folks adjust their coils using your method? Or are you saying that better than 90% of the folks who use your method "know the remarkable difference"? Or...? Sorry, that part wasn't clear to me.

[JohnH]

Better than 90% refers to the firing consistency. For example, if the coil is fired 100 times in rapid succession and the dwell time remains constant for at least 90 of those firings.

This coil has 98% firing consistency when tested at an equivalent engine speed of 2000rpm.

[Hal]

Thanks John.