Question about "Model T coil tester advice: HCCT, Strobo-Spark, ECCT, part 2"

[Been Here Before]

I am curious. If I should forgo my method of adjusting coils with the attached buzz box and not depending on the HCCT that I received years ago from an early Ford Dealership to set coils, what benefits would I feel or see?

With my methods of using the box and making certain the cushion springs are free, I can travel at 30-35 mph with no bulking or misfires. I can engage forward gears with no problems. The motor at idle is hitting on 4 cylinders. A smooth idle.

If I should decide to use an expert to adjust the coils or even invest in a modern coil eHCCT, what would I experience?

Better fuel economy? Faster acceleration from 0 to 30 MPH? Quicker starts? Even the magical free start?

Please explain to me how the new technology for coil adjustment and tuning is an improvement over the old.

I did attempt to find a dyno test between old and new coil adjustment and performance, so far no information. I may change my ways with real numbers.

And please, no colour line graphs comparing sparking habits.

[Luke]

George,

Depending upon how 'bad' your existing coils are set you may experience better fuel economy, smoother running, and increased acceleration from a coil set that is accurately timed. I don't believe it would make a great deal of difference to 'free starting' (although I managed more than 13 in a row with my 'FACT' set coils!).

The reason I qualify the above comment is because with the buzz box in particular there is a fair degree of latitude in the outcome of setting coils via that method. Clearly these coils will all provide EHT for the spark plug but, and this is the important thing to note, they may not necessarily do so at the same time when LT current is applied. You might get lucky setting them via the buzz box and find they're all pretty close, but the outcome will indeed be more likely due to luck than skill, or the 'accuracy' of the machine.

To be clear, at the instant you connect a battery (or mag), to any standard Model T coil it will provide the necessary voltage for a spark plug some time after that initial connection. If coils are not set via a timing method then that time will necessarily be variable, which in turn can mean a rotational spark timing variance of some degrees between the coils, and therefore a motor that cannot run at its best.

Buzz boxes etc do not set coils to time, rather they use a fairly crude average current setting which does not guarantee the same timing. The luck I mention is down to coil components, which were hardly 'precision' 100 years ago and, to a small extent, the operator. As they mostly use average reading moving coil meters to display results this introduces further variability.

To the best of my knowledge there are just two tools for setting coils to time. One is produced commercially by Mike Kossor, the other is a community project that you'll find on this site. I believe Mike has done some good empirical research into the outcome of setting coils to time, he may share this with you, otherwise the science and qualitative responses from people who've had their coils set to time with both tools seem unequivocal that the vehicles [should] start and run 'better'. Certainly you should get more consistent results between each setting of your coils than you would with other methods.

To conclude. If you're lucky and you have a set of coils that were produced on the same day by the same person and which have exactly the same turns of wire in the same layering and exactly the same capacitance, with points that have exactly the same properties etc etc and you set them via a buzz box there's a reasonably chance they'll not be too far apart with regard to their ramp timing. However after a 100 years there would be very few coil collections that are this way, if they ever were. Thus properly timing the coils is a good and simple first step in improving the consistent running of your vehicle, if that's an interest you have.

Luke.

[TXGOAT2]

As I understand it, Model T coils can misbehave in several ways, one being how long the coil takes to actually fire the spark plug after the timer makes contact. Distributor systems with a single coil will fire each cylinder very evenly assuming that the points, condenser, distributor shaft bushings, breaker plate/advance mechanism, and the distributor cam are all in good shape. The Model T system uses 4 separate coils, each with its own point set that is not cam-operated, and so each coil may fire sooner or later than the others when the timer makes contact. That can lead to a situation where where all 4 cylinders are slightly out of time relative to one another, which leads to some power loss and rougher running. For instance, let's say the timer was advanced such that the timing as at 10 deg. BTDC. With poorly-adjusted coils, and no other issues, Cylinder # 1 might actually fire at 7 deg BTDC, # 2 at 12 deg BTDC, # 3 at 10 deg BTDC and # 4 at 8 deg BTDC. This condition would likely be apparent to the driver as vibration or low power at some speeds or loads, or just overall sluggish performance. Using the electronic equipment, it is possible to adjust each of the 4 coils to fire at the same instant relative to the timer contact, giving the smoothest engine performance and maxiumum power. How much better the engine would run would depend on how far out of tune each of the coils was to begin with. An electronic timer can eliminate individual cylinder timing errors related to the mechanical timer.

[MKossor]

Model T engine performance depends upon many variables that must all be functioning properly for optimal performance to occur.

Weak link in the chain.JPG (26.11 KiB) Viewed 1645 times

Like all Spark Ignition (SI) engines, the Model T engine performance depends heavily upon proper spark ignition timing. The primary variables responsible for proper ignition timing are the timer and coils. The stock timer must be properly centered about the CAM shaft, in good condition and properly maintained in order for it to activate each coil at the proper time in relation to the respective piston position. The coil points on each of the four coils must be precisely adjusted for sufficient, equal and consistent dwell times to fire spark once the timer activates the coil to produce spark. Thus, coil point adjustment is probably the most challenging set of variables to achieve, especially back in the day when it was not possible to easily and precisely measure timed events with microsecond accuracy. However, they could accurately measure the average RMS current so the HCCT evolved which relied on the fact coils firing with equal dwell time to fire spark with periodic activation would draw the same average current. The average coil current draw was an indirect approximation for coil firing time. Here is an analogy.

You can most certainly rely on the trusty sun dial today as in olden times but there are more accurate methods readily available to measure timed events far more accurately. How well the indirect method works to adjust coils largely depends on how well the four coils are matched both electrically and physically as Luke points out. Also, there are some misadjustments like point arcing that delays spark timing but not easily detected or corrected by measuring coil current.

What will you experience if you adjust your coils for equal and consistent firing time more accurately? The answer is; it all depends upon all the other engine performance variables. Assuming they are all operating properly, especially the timer, the overwhelming consensus is you will likely experience a marked improvement in engine smoothness, acceleration and power. Improvement in fuel efficiency has also been reported.

[TXGOAT2]

I would expect to see improved economy and more consistent response to the driver's throttle, carburetor adjustment, and spark timing inputs... in short, a smoother, sweeter-running engine. Torsional vibration would likely be reduced in both bandwidth and intensity.