What tach will work with my motor

[dakota.jones]

i have a 1978 90 hp merc with thunderbolt ignition..what tachs can i use that wont burn up my ignition?

 

[ekern68]

i recently bought a tach for my 72 merc 402 40 hp. the company is called "tiny tach". the tach cost $47.00 . call them and tell them what it is for. they will customize it with extra wire any length you want and will install a noise filter for 10 bucks. you just wrap one wire around your bottom plug wire and ground the other wire. install took two minutes and it works great. call them instead of ordering on line so they can set it up for an outboard. very nice people. by the way, the tach is digital and is about the size of a box of tic tacs so it can be permanent mounted or removed to be used on anything else that runs on gas. registers up to 50000 rpm.

 

[fastjeff]

Had bad experiences with those Tiny Tachs (and I'm not alone).

Any tach that uses the stator coils instead of the ignition works great and won't harm anything. Look for a tach that is adjustable in back for various cylinders/ poles. Your motor has (I think) 6 poles.

Jeff

 

[dakota.jones]

well the problem with using the tiny tac then is i will have a giant hole in my custom dash i built lol

 

[wynjim55]

Can you use tachometers from motorcycles with the same number of cylinders as the outboard you fit them to?

 

[fastjeff]

No, unless you also have a 4 cycle outboard. Most non-specific application tachs have a switch in back for various cylinder setups.

Jeff

 

[wynjim55]

Would a 2 cycle dirt bike (or simillar) tacho of the same number of cyclinders work?

 

[dew2]

Tach has to match the poles on the stator.The tinytach works great for me working on different motors,BUT if you want one for a outboard it HAS TO match the poles,most tachs for outboards have a switch on their back just for that.tinytach works on all outboards if you get into multiple cylinders it may require a filter but for me up to 4 cyl.it has preformed excellent