For my yearly ignition tune up on the Model T Ford, is it correct to say that I could save $575.00 plus shipping and handling on modern test tools, if I properly maintain my coils. Providing the coils buzz, points are dressed, and, for example, make certain the cushion spring (A in the photograph) is free to move (gap .005"), and the points gap is set at 1/32" clearance? This should eliminate the double sparking and weak spark.
Fun Projects Strobo-Spark is a lot less than $575.
Oh boy, here we go again! Yippee!
There needs to be at least an initial adjustment of the coils on a suitable machine, after verifying that the capacitors are good, and the points are either new or in good condition. The point gap is really just a starting point, and is not necessarily critical to the operation of the coil if it is a little too much or less than the Ford manual states.
If you are only going to have one Model T then you want five coils so you can have a spare under the seat. I've never actually needed that spare, but I have loaned it to other Model T'ers several times. For the cost of five coils being repaired it makes sense to just send them to one of the excellent coil repair guys. You won't likely ever need another coil adjustment for a decade of driving if you are an average T owner.
You also should keep a spare timer under the seat. Good timers are very inexpensive; you can buy one from Tony Wiltshire for less than $75 including shipping for example. My preference is original Ford roller timers, I have found them in perfect condition at swap meets for as little as $1. At that price you could have as many examples as you want.
The Model T ignition system is extremely reliable and needs only a couple minutes of maintenance a year. The coils just need to be left alone - no need to constantly re - check them once they are set properly.
The only way to save $$ without you purchasing the correct testing units * is to send away your coils every year or so and have them adjusted/ and or points changed/ by a quality rebuilder...one like The Coil Doctor, Brent Mize.
Those coil points buzz at over 200 times a second, and will wear over use. Plus internally the capacitor can degrade. And then, trauma like rough handling can mess up the point contacts. After 6,000 miles or so, the coils should be re-tested, or at least carry a spare.
Overheating, missing, poor performance, lack of pull up hills, can all be related to incorrectly adjusted or worn coil or coils.
So back in the day, the Ford owner just trotted up the nearest dealer, and got a new coil or had the coils set and adjusted on the HCCT.
(the next figure in the page shown by you of the coil adjusting specifics)
Now if the owner back then didn't live near his dealer, and wanted to try to adjust coils, then he could buy some things sold then to help....
Like this mechanical gizmo that would weight the points of each coil evenly, in attempt to adj. each coil to its mate.
Then of course the buzz box type coil 'testers'
These units could at least pass some juice to see if the coil sparked.
So today, its very nice to have available to the advanced Model T hobbyist all the nifty new tools, from rebuilt or reproduced *Ford type HCCT, or the portable *Strobo-Spark tester, and the latest laptop compatible and mini-sized *ECCT.
All of these above qualified testing instruments are a far cry from the days of setting the points to a measurement, twisting the nut, banging the end of the vibrator, to the best sounding 'buzz'!
Dan provides a more realistic account of Model T ignition system set up and maintenance.
I've been studying the Model T ignition system for over 4 years now with emphasis on coil point operation. I use instruments which allow me to carefully monitor changes in coil firing consistency less than 1/1000 second which may seem silly but considering the crank shaft has a rotational velocity of 6 x RPM measured in deg/sec, that equates to 6 x 2300 = 13800 degrees/second and coil firing variation of 1/1000 of that speed is 13800/1000=13.8 crank shaft degrees. That's a HUGE amount of ignition timing retard! 2300 RPM is the top end on my 1927 Touring which is seen when pulling out into traffic. Coil points with well less than 1/1000sec (that's 1 millisecond) of ignition timing variation will not likely meet that top speed, craping out well below with considerable vibration, when engine power is needed most.
Coil testers with mechanical rotating spark gaps can capture the double spark event which is a weak spark that may occur early (advanced) but lacks spark energy to ensure combustion followed by another weak spark that occurs late (retarded) and also lacks spark energy. Increasing cushion spring tension eliminates the double spark event, however, does not guarantee the cushion spring is properly adjusted. The cushion spring tension may still be too weak, allowing the vibrator spring contact to pull away from the cushion spring contact slowly before the cushion spring reaches the limit rivet. This has the effect of permitting an arc develop across the coil points. Coil current still flows while the points arc delaying (retarding) the spark (and ignition timing). Point arcing is NOT readily indicated by mechanical rotating spark gap testers since some point arcing always present, making it nearly impossible to know when the cushion spring tension is set correctly.
The in ability to test coil point performance down to the sub millisecond resolution leads to the misconception that coil points donít need further attention for years once properly set. Coil point adjustment is much more sensitive than most folks think without any way to observe the performance changes. I always re-test and re-adjust coil points a second time after the point metal and coil wood have had time to relax from the initial adjustment. The timing drift is very noticeable using modern coil test equipment.
Another detail that just cannot be readily observe at abnormally slow hand cranking speeds is coil point firing consistency. A coil may seem to fire consistently at 120RPM or even 1500 RPM but gets totally random firing as top engine speeds, severely limiting the top speed where engine power is needed the most. Modern coil test methods which permit coil testing at 2000 RPM minimum is critical to attaining good engine performance on a repeatable and consistent basis in my experience.