Logo
FULL SITE MENU

Tachometer Calibration

A

AL23

New member
I have a 1997 Mariner 40ph serial 0G483527 and purchased a new tach. I believe the motor is a 6 pole, is this correct or is it a 4 pole? I count what looks like 6 coils but that is only half the difference around the stator. I am trying to calibrate the Tach to the correct setting. To verify its reading correct I am measuring the frequency in kHz while idling and in forward gear reads 0.3kHZ. Based on this my calculations would suggest the motor is idling at 6000 which can’t be correct. 0.3kHz x 1000=300Hz / 3 if my pole count at 6 is correct =100x6 = 6000 rpm. What am I missing can the voltage regulator be giving the incorrect signal?
 
Why you thinking 12 pole even that would put the idling at 3000. I can’t idle down the motor much less and it will stall. The motor shakes a lot also it much less. I also tried the 12 pole setting on the tach which is setting 5 and the tach only reads between 200 to 400 rpm not close to 3000. I am still questioning the .3kHz reading.
 
How do I know the tach is giving me the correct reading without knowing what the motor is putting out in order to calibrate the tach correctly. I don’t want to assume the tach is correct with out knowing what I should be looking for and then adjust the tach to match the motor. I was using the frequency reading off the tach signal which is giving me .3kHz which is 300Hz x 60 = 18,000Hz/ 6 being 12 poles and only 6 pulse per cycle = 3000rpms. What am I missing. My .3kHz read has to be incorrect right?
 
Try this....

How do you calibrate a tachometer?

Hello all, I purchased a used Telex tach off ebay. I connected it to a 1964 Mercury 650 (signal line on tach to the yellow line off the stator), set the unit to 12 pole (it was on 8 pole previously). Started the engine, and at idle, the tach read about 3K! I hooked my multimeter to the two...
forums.iboats.com forums.iboats.com
 
Back
Top