MTFCA Forum

Picked this up at garage sale today for $1, so no big investment if it isn't what I think it is. Sure looks to be a buzz box tester. Google search for STS coil tester brings up an old listing for Mac's sellit it as a Model T coil tester, but Mac's is gone and the link does not upgrade to Eklers so I'm presuming this product is no longer being built or sold.
Anyone seen one of these? Anyone have one? And, more importantly...anyone have the instructions for one?

It appears to hook up to a xic volt battery, but don't know what the two fuse clip looking things are for. Spark plug?

I'll hang up and listen.

It is a Buzz Box Coil Tester.
Not an appropriate test device for Model T Ford ignition coils.
Ron Patterson

That box will tell you if a coil is bad when you see no sparks in the small hole.

The box cannot tell you if the coil has random misfires.

The box will also test spark plugs if you have a good coil to be tested at that time.

Those two little clips simulate the spark plug leads.

Those boxes come in two sizes, the larger coil size prior to 1912 can be tested in an earlier box.

Stafford is the name of the company that made and sold those boxes.

I have two of each size boxes.

Do the battery leads clip onto a 6v car battery? Or a smaller 6v dry cell lantern battery?
Is the buzz box tester just a pass/fail? It sparks or it doesn't? Or is there a way to use this to find a matched set of coils?
I'm thinking $1 was about the right price.

The leads connect to a 6V car battery. An alkaline 6V lantern battery can also be used for short term use. I wouldn't recommend a cheaper carbon zinc battery in view of the current draw, although it will work to a degree if the battery is particularly fresh. Once the contact gaps are set, the coil vibrator tension is adjusted so the meter shows 1.3A.

It can be used for a pass/fail test in that the coil buzzes and sparks, and can be used to set a coil so the car is drivable, but will not provide the adjustment necessary for optimim smooth running, particularly for magneto operation.
It's the kind of thing to keep under the seat for emergencies, but not as an instrument to provide best possible performance.
And it's definitely not suitable for finding matched coils since it cannot show firing characteristics of the coil.

So if I adjust 4 coils so they all read 1/3 on the gauge and they fire a plug, it's better than nothing, correct? Like you mentioned, something to use in an emergency or for an initial start after a restoration, but that further testing would be need for optimum performance. When I slowly crank my engine over after sitting for several years and working on a restoration in progress, I can hear all four boxes buzz, but all at a very different pitch. I was under the impression that they should all sound close to each other in buzz pitch. Perhaps not an accurate observation. So putting the coils on this contraption and connecting to the 6v car battery will tell me something I don't know now, I presume.
And that I should see the same color spark on four spark plugs if they are set correctly and using the same buzz box as a test bench.

I might as well play with it to get my $1 worth out of it.

Yes, better than nothing.
It wont detect double sparking.
It wont lead you to the correct adjustment for that even "clack"
It will give you even amp draws & by watching the meter jump/wiggle detect some inconsistencies.

It will cause you to fire on all cylinders, however, sometimes when you have higher compression such as starting from a stop of pulling a hill, the weaker spark will not fire the gas or will fire later than the others so the engine will be a little rough. When they are matched, and running on magneto, the best results occur. Even the setting of the gap in the spark plug will make a difference.
Norm

The Model T was not designed to be a high performance vehicle. And the coils are designed to be judged as go or no go.

The discussion as to the best way to adjust coils will go on for ever.

I don't have a STS coil Tester, but I do have my own design tester and current adjuster instrument on that operated on DC and one that operates on AC. Both give be coils that allow me to operate my T and travel at 30 mph.

"The discussion as to the best way to adjust coils will go on for ever."
As long as there are those with a "religious" attitude & stubbornness there will be neighsayers.
I will not try to convert your attitude. Some folks have no need for more than 30mph. Fine for them.
I have discovered thru my own testing that tuning with an ECCT unit optimized my engines performance without going to a distributor.
Why do so many run distributors?
A properly tuned set of coils will give you maximum engine efficiency. Optimum speed, hill climbing ease & least motor strain & wear.

Dont you suppose that each T that left the factory had a set of new, perfect coils, Just by the nature they were all the same set & parts?
(Unless the got bounced or hit before installation.)
Lets not forget that the earlier(pre 14) coils gave much grief leading to the popular "master vibrator" way to get the engine to fire accurately.

If you ever get the chance to try a set of ECCT set coils you will notice a big difference unless you have so perfected your buzz box tuning method such that all your coils fire as accurately as ECCT tuned coils. Wouldnt it be worth a try for your own knowledge base?

My T averaged 53+ MPH in the Montana 500 using a Ford system and a New Day timer. Setting the coils "by ear" after a coil point failure gave me very poor performance. VERY poor... and it began eating timers.
Setting the points with motor running made the car drive-able again, but it did not run right and was still hard on the timer.
I set the same coils with an ECCT and cleaned up the damaged timer, and it has run well ever since. (Several thousand miles)
This car is very close to stock, as per Montana 500 rules, and it will easily do 45 MPH all day long. I usually run it about 42 MPH on the open road. It will go faster, but I'm not racing, so I keep the speed down to 45 or less.

I'm sure that a great many Model Ts ran with out-of-adjustment coils back in the day. It's safe to say that many still do. Setting the coils by ear probably will not give good results. The early coils with the single contact points might be more amenable to adjusting by ear than the later ones. Many Ts, then and now, routinely run with improper coil, carburetor, and spark timing adjustments. They run, but they do not run as well as they could if properly tuned and with correct use of the driver controls.

"The discussion as to the best way to adjust coils will go on for ever."

"Setting the coils by ear probably will not give good results. The early coils with the single contact points might be more amenable to adjusting by ear than the later ones."

If one uses the standards of the day - a properly adjusted coil will draw 1.2 -1.4 amp. The the coil, all thing being in alignment (proper cushion spring adjustment) , will give the performance needed for daily use.

If I want a car with adequate performance then, park the T and drive a Tesla. The soul purpose, in my feeble mind, is to experience the discovery of a early T owner.

See Automobile Engineering 1921. On all thing automobile electrical - and coil adjustment.

I repeat.
Borrow a set of ECCT adjusted coils & try them once.
You will feel the difference.

I prefer a "smooth, even purr". I can drive a well-tuned T without buying a Tesla.

FWIW, I do not own an HCCT or any other antique testing equipment.

That STS is designed for the early coils and has the bottom coil connection slightly to the right.

So, the newer coils have to be set slightly off straight or the test set appears not to work.

You can see the col sparks coming of the termina and in the small window to the right of the red spark plug connector for testing those.