New tach reading on 1970 Merc 650 (thunderbolt)

C

cburgess129

Recruit
Joined
May 15, 2006
Messages
3
I added a mercury tach to my 1970 Merc 650 today. I had to move the pickup wire (brown) from the electronic control module to the stator-side of the rectifier. I set the tach to the 6P position (for 12-pulse merc motors)per the instruction manual. The tach reads 1100 to 1200 rpms at idle in forward gear. The specs for idle rpms for this motor are 550-600. Seems that the tach is reading exactly double. How do I tell if the motor is actually idling too fast or if the tach is reading incorrectly?<br /><br />Thanks! <br /><br />Chris Burgess
 
rickdb1boat

rickdb1boat

Supreme Mariner
Joined
Jan 23, 2002
Messages
11,195
Re: New tach reading on 1970 Merc 650 (thunderbolt)

The only way to verify it is with another Tach. that is known to be reading correctly....Does it sound like it's idling normally?
 
C

cburgess129

Recruit
Joined
May 15, 2006
Messages
3
Re: New tach reading on 1970 Merc 650 (thunderbolt)

I think I found the problem. I have it on the mufffs. I need to take it out to the lake and check the idle on the water in gear. If it reads incorrectly there I will be concerned.<br /><br />I will post an update for the record once I test it out.<br /><br />Chis
 
You must log in or register to reply here.
Top