Has anyone used one of these?

https://www.modeltford.com/item/A-MAGM.aspx

I was thinking of getting one to use in the blanked off ammeter hole of a '25 dashboard in my non-electric T, and was wondering how well it would stand up to the vibration, etc... Thanks, Jack

I have 3 of them. The needle pegs out at 30v at about 25mph. It removes any doubt that my magneto is functioning properly. All are mounted with the bracket https://www.modeltford.com/item/A-MAGM.aspx
only screw holes have to be drilled in the bottom lip of the dash. No big holes necessary in the face of the dash are required, not in my situation anyway.

Here's one of two originals I have.

I have one on my '14 runabout. It performs exactly as Bill reports and I like it for the same reason he states. I suppose you could position one in place of the blanked ammeter. I bought the accy bracket and mounted mine into the wood on the upper body panel just beneath the Klaxon horn.

Dash mounted mine in the '27 as the dash board was holed and rusty to start, one more hole didn't mind!





Idle speed, really like this gage too!

I have one and continue to use it, but i am not imprressed. Once i get above 25mph it flutuates back and forth between 20 and 30. What help is that? It should be a steady voltage. This is a brand new rebuild that runs great on mag.

What about the Magneto Meter itself Dave? Has it been rebuilt? I wonder if maybe there's a pooched condenser inside or something.

Those are nice as dash art and tell you the magneto is doing "something", but they supply little meaningful information about the health of a Model T magneto.
If your trouble shooting a Model T magneto you will need something that is designed with an internal load that is calibrated to tell if the magneto is healthy (current carrying capability) through its entire voltage and frequency range.
Here is the best tool you can have for definitive magneto testing.
Saint Louis Magneto Tester

Saint Louis Magneto Tester

Or a HCCT with a similar coil and circuit in place to give the same load. Many but not all HCCT also supports measuring the output from the magneto.

A quick test of your mag is to short it to ground with a screwdriver. If you get a lot of sparks your mag is fine.

Another tool to effectively test and diagnose magneto performance issues is the ECCT with Magneto test and Software options.

A numeric value of Magneto Field Strength is provided, Under Load, as a clear and accurate standard for comparing Magneto health over time or car to car. Other useful information provided is engine RPM, True RMS Magneto Voltage Output at that RPM and Magneto post contact resistance that helps avoids needless disassembly to check if the magpost contact is good.



More information is available on page 30 of the manual: http://www.modeltecct.com/uploads/ECCT_Instructions.pdf and on the website: www.modeltecct.com

Thanks everyone for the information. When I saw this listing in the catalog I was curious if the meter movement was sufficiently dampened that it would be both long lasting and readable at road speeds...it never occurred to me that reading only open circuit magneto voltage would not give an adequate indication of magneto condition, until it was brought up here. Guess I don't need one...