tachometer?

[jonnymarquis]

have a 1977 70 hp evinrude. i need to know if any tach will work? i found one at part store for 30 deer but noticed it said will work with all 4,6,8 cylinder motors but mine is a 3 cyl. so just want a cheap tach to install for this motor will any tach work?

 

[steelespike]

Re: tachometer?

Hopefully someone with more expertise will be along.To the best of my knowledge that tach is not for a 2 stroke motor.There are induction tachs that work off pulses from a plug wire and can be ordered and setup for a number of applications.Tiny tach is one.
Outboards require a tach specifically designed for outboard systems.Usually they have settings to match a number of types.

 

[Silvertip]

Re: tachometer?

You are looking at an automobile tach and that won't work on your outboard. Outboard tachometers receive rpm pulses from the alternator and therefore are not dependent on the number of cylinders. You need either a Tiny Tach or a genuine outboard tach. Outboard tachs have a calibration dial on the back that can be set for the number of pulses the alternator on your engine produces.

 

[cr2k]

Re: tachometer?

2 stroke marine tachs depend on the number of poles in the stator. They run off the charging or ign systems.

 

[Joshua Nichols]

Re: tachometer?

Gotta have one for a outboard

 

[brantly]

Re: tachometer?

On this same note. How would one findout how many "poles" their outboard has? Any easy way to identify this? I have a 1996 Johnson 150 oceanrunner. Sorry. I didn't mean to jack ur thread!!

 

[Silvertip]

Re: tachometer?

On this same note. How would one findout how many "poles" their outboard has? Any easy way to identify this? I have a 1996 Johnson 150 oceanrunner. Sorry. I didn't mean to jack ur thread!!

It would be described in the service manual for your engine. But I'm betting you don't have one so the answer is 12 pole. Then when you look at the tach you will see there is no "12" so then what. A 12 pole alternator produces 6 pulses on the tach send line. Therefore you need to set the calibration dial on the tach to 6.

 

[jonnymarquis]

Re: tachometer?

silver can you give me a for sure setting for my tach? I'm not sure. and no one has really given me a for sure answer. and you seem very knowledgeable on this. thank you sir.

 

[MTboatguy]

Re: tachometer?

You need a tach, designed for an outboard, period...

 

[jonnymarquis]

Re: tachometer?

yes i know that and i have one. just need to know what setting to have it on.

 

[Barnacle_Bill]

Re: tachometer?

yes i know that and i have one. just need to know what setting to have it on.

6P is the correct setting.