I've been watching the E-Timer post with a great deal of interest, as I believe I know of another way to get better performance with the stock ignition system.
I introduced this notion a few years back and I was chastised by the experts for introducing such a notion.....perhaps rightly so.
Anyway, since then I have had the opportunity to test this idea at Talimena Drive in the Quashita mountains in southeastern Oklahoma. Yeh I know there's not supposed to be mountains in Oklahoma but several pilots have found out the hard way. Talimena Drive is a 60 mile drive thru the Quashita National Forest along the ridge of the mountains, 13% grades in Oklahoma and Arkansas, a fun drive in a Model T. I run 12 volts in my Center Door, very satisfactory. However...when I switched over to the double stack mag, the performance was immediately improved, "pulled all the hills in high gear. I was so impressed and tho it wasn't on the scheduled tour, I turned around drove the drive again. Why the improvement in performance? Voltage? What?
That's the fun of the Ford magneto, it puts out AC current, at running speed, right at 28 v AC. That is a big difference to those trembler coils than stingy 12 v DC.
The magneto will really fire those coils to give a hot spark at the plug, making more power for the 22 hp engine in your Ford.
Am a magneto runner, always, 6v or 12v dc storage battery is ok to start a Ford, but for me, running on magneto is the only way to go Ford T.
Magneto Meter in my '27 registering AC volts at fast idle. At speed, hits the 28-20v mark.
That's about what I get at speed, 18. Idle is only about 12. Wonder if you can get those magnets a little closer without pulling the engine to increase output? Also wonder if that affects my mileage??
The Model T ignition system relies on the ever increasing voltage and frequency of the magneto output to make the coil operate faster (decreasing the coil rise time from timer contact to 3+ Amps to fire the spark plug) as engine speed increases.
As you know high speed Model T performance on 6 volts DC is poor, 12 volts is better, but nothing beats the magneto for the best operation.
You would have noticed the same observations if you had installed a single stack field ring in the magneto. All properly operating Model T magnetos produce power far in excess of what the coils actually require to work correctly.
Several years ago I addressed the essentials of this issue in an article that appeared in the Vintage Ford Magazine.
More on Model T Spark Timing
I hope this helps.
Ron the Coilman
Ron: Thanks for sharing the spark timing article. I wish that were part of the Electrical System handbook.
Since the coil fires on 3 amps on both a 6 V and 12 V battery, I assume it also fires at 3 amps on Mag? If this same coil were operated in the HCCT would you see 1.3 Amps RMS for the current reading? The theoretical RMS value of a sawtooth wave form of 3 Amp amplitude seems to bear this out, or not?
Ron - Something you said in your post above prompts a question:
Ignoring for a moment the fact that Model T magneto is best for performance, you said, "high speed Model T performance on 6 volts DC is poor, 12 volts is better...."
My question is, if any constant voltage DC source (read battery) was available, what in your opinion would be the best "compromise" constant voltage for good performance without adverse effect to the coils?
I have a Hot Wally mag and as long as you give it a little extra advance for starting it is perfect! I also use a mc 12 volt for showing off and i have noticed better starts after prolonged sitting with the battry charger on it! Like my spelling im not shure what any of this means?? Bud.
Well, I didn't get said what I wanted to say, so let's try again. I have driven any number of Model T's with a single stack mags including the Center Door. But I felt like the double stack was giving me better performance than any single stack. Is that possible? I was using Ron Patterson Coils in both cases.
There is no doubt that 6 VDC is good, 12 VDC is better and a "hot" MAG is best for a "top" performance running "T". But, if you want to get to the additional "edge", the E-Timer, with its Automatic Timing Control, does it! I know; I've experienced the difference!
Since nobody answered your question as you asked it, let me give it a shot. Since you think you felt a difference then I have to return the question to you - did you feel a difference or not? The evaluation of any system without any real numbers or measurements other than "feelings" or "impressions" is just more speculation. Oprah proved this on a program of hers once. The power of suggestion is well known. Not trying to skirt the issue but here is what I make of this. The coil will fire at a particular magnetic field strength within its windings and so the strength of the spark would be basically the same with either magneto coil. The main difference and theoretically the only difference would be in timing with either better intra-cylinder timing accuracy (the ability of the magneto to cause a coil to fire at precise 180 degree intervals of the crank shaft) or more or less total timing advance. The timing change being caused by the placement of all coils with regard to the crankshaft magnet positions and the waveform generated as the magnets pass the coils. Assuming that the placement of coils was perfect then the gap of all coils to the magnets would affect timing by virtue of the wave shape of the magneto coils being different from double stack to single stack. There is little doubt the waveshape would be different but whether that is better or not depends on what it does to the timing and whether more advance or more retard at a particular RPM is better or worse with regard to "performance". I use the term performance generically but it really depends on what you want at the moment - more torque? - more RPM? The question in my mind mainly is this - replacing one system with another without really careful measurement of both systems before and after could lead to some erroneous conclusions and bad science. Would you have felt the same improvement if you had replaced your single stack with just a different single stack? You might indeed if in the process you naturally changed the gap too since it would be nearly impossible not to have done so. The output of the magneto is increased by the square of the gap distance reduction so if in the swap of single stack to single stack you also decreased the gap distance even a small amount, you might notice a difference in the performance too. To see whether a double stack is "better" than a single stack you have to do measurements on a number of them and have some means to accurately record the amount of "better". Most engineering begins with a design of a "test bed" method to measure something. The Wright brothers would never have flown had they not first designed a wind tunnel.
Thanks John. I knew it was not a good test situation.....but it sure did run good! I have now ruined the engine. Installed a counter balanced A crank, B cam,Z head, 4 tube splash oil system, Winfield intake and carb. I hope to drive it up Pikes Peak this summer. This will be close to the engine that was in the Pietenpol Sky Scout except the Scout had a VW full oil pressure systen and a Tillotson Carb.
We are in process of transfering ownership of the Sky Scout to the MTFCA. We are restoring the engine to running condition. The 28 crank that was in the plane had two large cracks in number 3 journal, so we installed another counter balanced 28 crank. It would not be too difficult to return the plane to flying condition. I'll let Jay make that decision. Chris Esgsaard flew the plane a lot during the eighties and Nineties. I don't yet have the log books although they have been promised several times?? This plane also has great historical significance since it is the very first Pietenpol Sky Scout; built in 1931.
I know little about a T magneto but found it interesting that checking some fifteen used coil rings trying to save my green the one double stack checked was by far the best of all.
John, well said.
Paul, better in what way?
Magnatism,---- Made up a board with an adjustable hack saw blade that sat on the coil face. Checked each coil with six volt then twelve volt. The double stack would hammer the blade down to the coil with more gap then any of the later coils would.
I am probably wrong in some respect but thats my obsevation!
Paul, the fact that it had better magnetism could be a function of more current in one coil than the other (due to wire size e.g.). But, if the current were the same, and the magnetism were more in one than the other, then I would say the one with more magnetism would definitely be a more efficient electro-magnet (higher q factor). This does not mean that it would have to be a better transducer, (which is what a field coil is) although that could be, and probably is the case. As a practical matter, I still think the bottom line is "good enough is good enough".
My thinking is with logic! all the coils tested with my method were the same with a double stack!! Dont know if my logic is right or or wrong---------------- its just logic! Ron, John and others with far more knowledge then myself can take it for what it is!!
Merry Christmas!! Paul