How fast is my engine going - RPM

Aside from the safety issues, it is handy to know your engine RPM when you run your engine under load to gauge how well it is coping. Some people rely on hearing the engine firing on every cycle (the engine is running slow enough for the governing mechanism to allow firing every firing cycle - where as with no load, the engine will only fire often enough to make the revolutions you have set) to determine if their engine is working hard. This is not enough. To avoid straining your engine you should ensure it is operating at the appropriate RPM under load.

In early 1997 I found a device manufactured by a company called Record which is essentially a counter with a spindle. Every revolution of the spindle increments the counter by one. To measure RPM you reset the counter to zero zero zero zero and press the rubber or steel tipped spindle (use the attachment appropriate to your shaft speed - under 1000 rpm use the steel tip, between 1000 and 9999 rpm use the rubber tip) against the shaft for one minute. At the end of the minute simply read off the counter in RPM. You do not have to measure for a whole minute, but most old engines do not run smoothly and some revolutions are faster than others - it is a good idea to stick with measuring over a minute to ensure a reliable result. The Record counter will operate both clockwise and counter-clockwise. My Record revolution counter cost $A40. I found it in a "junk" antique store, you know the kind, the ones with "antique" in their name, but it should be "junk" rather than "antique".

Some other counters are featured below:

	Record Probator Counter. Same as the Record Counter except that it includes a built in stop watch which times how long the counter has been in service since last reset.
	The S.I.C. Pocket Speedo (marked V1738 in the picture) measures rotary speeds up to 3000 RPM and lineal speeds up to 500 ft. per minute in either direction. This tool is used both in the measure of shaft revolutions, and the speed at which belting (v or flat) is traveling in feet per minute. The other tool is a true tachometer which gives you a reading in RPM (revolutions per minute) regardless of how long the device is held against the shaft. Of course the longer it is operated, the more accurate the reading.
	The Starrett Speed Indicators are made in three different types for measuring speeds. Each device has a steel shaft and two different rubber tips to handle both round and square shaft dimples. The uppermost device measures RPM up to 10,000. The middle device is the same as the top one except it is electrically insulated. The bottom device is used for measuring belt velocity in feet per minute.