Tach ???

[Les Young]

I have a 93 Sprint 255 with a 92 Johnson 70 hp. The tach was reading 7100 at wot. I adjusted the tach & now it says 5900 at wot. There seems to be no clicks on the pulse screw on the back of the tach(according to the diagram for the tach it has 5 different positions & it's the original that came out in the boat. My ??? is how do I know that I'm not getting false readings from the tach??? At idle it's showing 1100rpm & 5900 at wot so I'm just backing out of it & running at 5400 if the tacs right.The prop is a 17. I tried a 19 & it seemed to run the same.

 

[Joe Reeves]

Re: Tach ???

The dial on the back of that tachometer should be set on #6 .

 

[Les Young]

Re: Tach ???

Thanks Joe, but according to the diagram for this original tach it only has 5 positions. Should I turn the screw all the way to the right. I can't feel any clicks as I try to adjust it.

 

[another todd]

Re: Tach ???

Look closely at the back of the tach. There are numbers there, and an arrow on the adjuster. Set it to the correct number.

 

[Joe Reeves]

Re: Tach ???

I'm only familiar with the OMC tachometer that has a dial on the back of it whereas one of the positions is clearly lettered number six (6).

The tachometer operates off of the engine's charging system that emits six (6) pulses, hence the number six (6) setting. Your engine requires this type tachometer.

If your tachometer does not have this setting, I don't know what to tell you and will back out of this problem to let someone that is experienced with your tachometer advise you.

 

[Les Young]

Re: Tach ???

I looked again today & there are no numbers for the different settings on the tach, but there are numbers on a diagram that's under the back of the deck where you raise the lid to get to the batteries. this is the only sign of anything that has to do with positions on the tach.