Small Tachometer Question

[Shane733]

First I want to say thanks for letting me join your forums. My grandparents just gave me my first boat. It is a 1968 Larson with a 1968 Evinrude 40hp. It has about 40 hours use on it and after cleaning it up, it looks very close to brand new. I have alot of questions about this boat I want to know so here is my first one....<br /><br />I want to install a tach. I know I can get a Tiny Tach but I want to know if I have an option of using others. Reason I ask is because I have a wire under the front for a tach I think. It says its a TACHOMETER GROUND LEAD. Is this the send wire for a tach? The motor is a 2 cyl., model number 40852D. If other tachs work, do they just need to be set for 2 cyl? Is there a way of testing the TACHOMETER GROUND LEAD wire with a voltmeter to see if it is a send signal wire? <br /><br />Thanks for any help on this.

 

[rickdb1boat]

Re: Small Tachometer Question

You can get any Tach. you want, as long as it's able to be set on 6 pole. Set it on "6" pole and hook up the gray wire, hopefully,(Under the dash), ignition wire to "I" terminal and of course the ground to "G". Teleflex makes a bunch of them. Cabela's, Overton's and of course, I-boats right here has them. Most have settings for 2,4,6 pole. That's what you want...

 

[Shane733]

Re: Small Tachometer Question

Thanks rickdb1boat. <br /><br />So as long as it is 6 pole, it doesnt matter if it is for 2 cycle, 4 cycle, 2-4-6-8 cylinder? Sorry for being so dumb.

 

[Shane733]

Re: Small Tachometer Question

After a few more hours of reading I think I have looked over something. I dont think my motor has an alternator. I do have the gray wire under the dash but im not sure whats its connected to on the motor. If i dont have an alternator then a regular tach just isnt going to work for me is it? I posted a picture below if if helps any.<br /><br /> http://members.aol.com/shane733/boatmotor.jpg <br /><br /> http://members.aol.com/shane733/boatmotor2.jpg

 

[lark2004]

Re: Small Tachometer Question

Unless I have missed something, your engine doesn't even have it generator. Only the starter motor. I am in the middle of rebuilding a 1968 lark motor myself and am faced with a simalar tach problem, I am considering building a digital tach that is triggered by the spark lead, via an inductance pickup. If you are interested, give me an email and I will keep you posted. My E-mail is arcondie@bigpond.com

 

[Shane733]

Re: Small Tachometer Question

Thanks lark2004. I checked it out today and traced the grey wire down. It looks like it is grounded to the CUT-OUT SWITCH MOUNTING SCREW just as the manual says.<br /><br />Just because i have this grey wire, and it is hooked to something on the motor, that still doesnt mean i can hook a tach to it because of no generator right rickdb1boat? I will have to go with a Tiny Tach right?

 

[Shane733]

Re: Small Tachometer Question

I got a 6 pole tach on the way to try. I did get this email from teleflex that has me worried though...<br /><br />Hi Shane, a generator does not have magnetic pole and so can not be used as a tachometer signal. If you had a 4 cylinder we could treat it likle a car motor with points and set the rear switch (tach) to 4C/2P (4 cylinder, 2 pulses or firings per revolution). A 2 cylinder (1 pulse per revolution) we can not. I’m afraid we do not have a tachometer for your application.<br /><br /> <br /><br />Sorry, but thank you for thinking of us. You may want to go to a Johnson/Evinrude dealer for a tachometer.<br /><br /> <br /><br />Joe ******XX<br /><br />Tampa, Florida, Home of the 2004 Champions Tampa Bay Lightning