PDA

View Full Version : Outboard Engine RPM



Alan Peck
10-23-2005, 12:41 PM
Does anyone know if it is possible to use a digital Multimeter with the ability to measure frequency to measure engine rpm? I have access to a Fluke 83 III.

Or do you need some type of $100 adaptor? If that's the case I might as well buy a permanent tachometer and install it on the console.

If it matters, my outboard is an Evinrude with a Type II CD Flywheel Magneto Ignition.

Thanks

paladin
10-23-2005, 01:36 PM
Go to a store that's really heavy into model airplanes....or get a magazine devoted to large scale models...a device called "Vibra-Tach"..I think... a device that will measure sympathetic vibrations for engine rpm....

P.I. Stazzer-Newt
10-23-2005, 02:24 PM
Tiny Tach (http://www.tinytach.com/tinytach/gasoline.php)

I have used a home-brewed version of the Vibratch - calibrating it was a bit of a bitch.
Vibratach (http://www.manddsmallengine.com/tecumseh/tools.html)

Paul Scheuer
10-23-2005, 05:06 PM
Vibratach is the multiple tuning fork device, right ? All mechanical - nothing can go wrong.

My old truck did a similar thing. After the speedometer went out, I drove the last 100,000 miles by listening for which parts rattled.

Alan: I've never done it but it would be a quick experiment. Just hook up to anything electrical on the motor. You might get multiples of the actual frequency, but if it's stable and tracks motor speed increases/decreases, it should be a reliable indicator. You'll need to make a conversion from Hz to rpm anyway, so you can figure the multiple.