rpm gauge - switch at the back

[Toffy]

Hi guys!

At the back of my rpm-gauge there's a black set-switch which influences the rpm-reading. I can set it from 2 to 6. (see the pic) Depending on the setting, my rpm-reading changes by +- 500rpm....

Does anyone know what the correct setting should be ?
My Engine turns max at 6000rpm (ignition cut off at 6700rpm)
My gauge stops at 7000rpm

I plan to do a measurement with the right stroboscope equipment and compare it to my gauge reading, but maybe you guys are familiar with this switch and can tell me what the setting should be ???

I find all this quite important because I lifted the engine of my boat a bit and I'm turning higher revs now... I always felt 'safe' in being under the max rev limit of my engine.
But I wanna be sure...

Thx! T.

[nigelk]

As I inderstand it, the numbers on the back refer to the number of cylinders in your engine.

If not I'm sure someone will confirm otherwise.

[Jon Fuller]

Yeah, there are usually numbers to represent how many cylinders, 2, 3, 4, 6. then another marked '12 pole alternator'. This 12 pole selection is the normal setting for OB's

What make is the Tachometer?

[Toffy]

Thanks Jon & Nigel!
This learns me my setting was wrong (see pic). As I have a Evinrude V4 it should be 4 instead of 6.

Don't know the make sorry. There are no ref numbers on it... only a symbol at the back that looks like an 'M'... it's visible on the picture. I notice that other ringowners have exactly the same black gauges with red needles. I guess these gauges came standard on rings...

For what it's worth : still gonna do a stroboscope measurement, just to test the accuracy of my gauge. I expect it to be exact.

Greets

[Jon Fuller]

The 'M' symbol suggests it's a genuine OMC (Johnson/Evinrude) product.

Not sure if they have the 12 pole alternator/tacho or not.

[Nasher]

My old Johnson 150VRO was 12 Pole.
That was a 6 cylinder however, so may not be the same, although I expect they just dropped the same alternator on top of all the V motors.

Nasher.

[Toffy]

Hi guys ! Last week I changed the setting from 6 -> 4.
At top speed I get now 7000 upto 7200rpm...

Impossible if you ask me. Enginesound is the same as ever... : great that is

Something must be wrong.
Although it looks cool to see the needle going out of scale, I wanna know my exact rpms...
Still plan to do an rpm gauge test...

Greets to ya all!
T.

[bigboy]

Haha, you have to set 6 instead of 4. 6= 12pole! And a V4 is 12pole. I have the manual of those rpm gauges. And looked it up for you!

[Toffy]

Hi!
Thx for the info!
Still didn't do a rpm gauge test, maybe after the winter :-)
Greets