Farmall Cub

I could never pull the trigger and spend the cash on a S&W or other quality hand held mechanically driven tachometer since I seldom work on anything that is impossible to get a RPM reading from, either mechanical or electric.

Too much money for too little use. I traditionally adjust high idle simply by ear.

I have a free satellite powered speedometer app on my smartphone (Android Ulysse Speedometer) and when paired with data from the manual, it works just the same as a tachometer.

Since my magneto equipped cub has the original size tires and my high idle is apparently set fairly close to 1800, it clicks along at a 7 mph in the big hole all day long.

I checked my other cub which I have set with an electric tach as close to 1800 as possible and it also runs a steady 7 MPH on the speedometer app.

I know not everyone has a smartphone but I'm sure one of your grandkids probably does and would be happy to download the app and let you borrow it to check and adjust your high idle setting if necessary.

Just one more trick of the trade to add to our arsenal thanks to modern technology.

When I first purchased my magneto cub it scurried along at 12 MPH because the governor rockshaft was all jacked up and I believe the previous owner may have turned it up attempting to juice a little more power out of it for the Woods 59 Mower.

Was the engine really turning 3600 (it was really screaming) or is there math involved in rpm calculation in relation to road speed?

I've use Garmin GPS to check the accuracy of vehicle speedometers. Think they should be able to check a Cub's ground speed.

Was the engine really turning 3600 (it was really screaming)

the guys that did governor work to their cubs and then put them on the dyno would do over the 3000 max reading on the dyno tach. Ralph reported that Flamey was touching the 4000 area(if my memory is correct)

Rick

If 1800 rpm produces a speedometer reading of 7 mph, it would seem only logical that a 12 mph reading would be over 3000 rpm but that seemed almost to easy to calculate! Thanks for the info Rick.

lazyuniondriver wrote:If 1800 rpm produces a speedometer reading of 7 mph, it would seem only logical that a 12 mph reading would be over 3000 rpm but that seemed almost to easy to calculate! Thanks for the info Rick.

Hmmm...the 1950 Cub I bought back in June was revved up to 4,000 rpm while sitting still. According to my Garmin, I had it up to 12 mph through the barnyard although Gary Dotson may have had it going faster than that at CI CubFest.

I might be a little dense but I am wondering why this is even useful. Tracking ground speed is fine if you want to figure out how fast you are going, but that is a limited application. For me I don't care about ground speed, it is immaterial. What I care about is the actual RPM's that my Cubs are developing in a specific setting - such as when I am splitting wood or even more critical when I am cutting wood on my saw table.

A Cub Tachometer like Brian's - Cub or Cub Loboy tachometer package

s.

although very nice looking and would fill the bill - is only for battery ignition tractors - aka distributor equipped Cubs. There is nothing for Magneto equipped Cub, aside from manual RPM gauges like a Stewart Warner 727W.

Now I would be very interested in being able to fabricate (as long as it isn't too difficult and doesn't need lathe work) a Tach setup that will work and be useful for me in the scenarios that I find my Cubs active in.

Rudi wrote:I might be a little dense but I am wondering why this is even useful. Tracking ground speed is fine if you want to figure out how fast you are going, but that is a limited application. For me I don't care about ground speed, it is immaterial. What I care about is the actual RPM's that my Cubs are developing in a specific setting - such as when I am splitting wood or even more critical when I am cutting wood on my saw table.

Rudi, what rpm's do you run your Cub for the table saw?

Rudi wrote:I might be a little dense but I am wondering why this is even useful.

I think being dense would be not asking the question. Knowing ground speed is the back door way around not having a tachometer to adjust high idle, sometimes known as max engine speed.

As long as your tires are the same size in diameter specified from the factory (I'm not going to nitpick tread wear) and you have the manual available with specifications indicating top speed in the various speed ranges or gears, you will have a pretty close estimate of what high idle is if road speed is known.

As you stated mag fired tractors are hard to set without a hand held mechanical tach. If a speed check indicates 10 mph, the idle needs to come down. Recheck road speed and adjust idle accordingly. (This would be the governor stop screw out front, not the carburator idle stop or mixture screw).

If a temporary speed adjustment between curb idle and wide open throttle is required with the engine speed control lever for a job specific task which engine speed could not be estimated by sound, visually, or by other means, a mechanical tach should probably be acquired.

Perhaps the mechanical rubber drive tip tach could be mounted on a magnetic dial indicator type base and swung against the driven application when necessary to clock its speed.

Rudi wrote:What I care about is the actual RPM's that my Cubs are developing in a specific setting - such as when I am splitting wood or even more critical when I am cutting wood on my saw table.

In both of the uses you mention, the Cub is stationary. You should be able to use an inductive tachometer to check RPM in these situations. It wouldn't be a permanent installation, but it should give you the information you need. Because the speed control lever sets RPM, you could even mark the notch for various speeds for future reference.

Michael:

I know, that is what I use the Stewart Warner 727 for .. as a hand held. It would just be nice to have one mounted that is visible -- probably equally from the seat and behind the Cub when I am working in the rear. It is more of a curiosity thing.

Denny:

Don't know yet. That will be something I have to determine. Going to be using my belt pulley - 8" diameter I think it is and the well casing that is on the saw table --- I think that is around 10" or so. The saw blade is 26" +/-. Have to figure out what the safe speed is then determine the correct rpms for the belt pulley to turn. Still in the thinking stage -- but getting closer to actually using Granny to power the saw table. 3 grand should be where the blade might have to be +/-, -- a little math then to determine the required rpm's and the tach to keep it there.

For my table saw I use a 1-1/2 hp 220v electric motor powering 10" ATB's, 7 TPI Rips, 40 tooth cross cuts

lazyuniondriver:

To determine ground speed I have 2 Garmin GPS units. One I use for prospecting and one I use in my old 2000 DGC. Both are battery/hand held units that track pretty efficiently.