installing a tach

[dxdennis]

I hope that this is the right forum. I have a<br />1975 Evinrude 70HP and I want to find out how<br />hard it is to install a tach, if I need to <br />purchase a marine tach etc. The outboard is a<br />three cylindar, 2 cycle. My owners manual says<br />that there is a tachometer lead provided in the<br />remote control. Any information about how to drill<br />a hole in the fiberglass, identify the lead in the<br />remote control or anything else about installing<br />a tach would be greatly appreciated.<br />Thanks<br />dxdennis

 

[SCO]

Re: installing a tach

It's real easy to do. I dont know if an auto tach will work,I imagine it could be done, but marine ones can be had for cheap. <br /><br />Ive got an earlier model Johnson than you , and think you will find 2 wires already hooked up in the control box to a plug or wires you can access from the outside of the box(my plug is below the keyswitch). One you can easily check with a voltmeter, will be a switched(with the key switch) positive 12v to power the tack. The other will be the signal for the tach. If you have a dash with a cutout, get a marine tach that fits. They come in standard sizes. There will be leads on the tach for instrument lights, tach power(12v red +), alternator pulse signal and ground. There is also a switch for the number of alt poles for your motor. The teleflex site indicates you have a 12 pole alternator, and will set for 6 on the back of the tach. I got a dusty old aqua marine for cheap from my local dealer and set it for 6p in the same way. You might confirm the pulses with a dealer service dept. If you set the pulses wrong, the tach will indicate an incorrect rpm.<br /><br />I also read about a micro or mini tach people like that also has an hours meter.<br /><br />Finally, I wouldnt drill into anything. Take the box apart(disconnect battery 1st) if you cant find the leads. I did that and found they were already hooked up to a plug on the box.

 

[rickdb1boat]

Re: installing a tach

dxdennis,<br />You can get a Tiny Tach here, but it is easy to hook up a regular Tach on your control as SCO said. But it is an option and very simple to install.<br /><br /> Tiny Tach

 

[DJ]

Re: installing a tach

dxdennis,<br /><br />Look for a post from me, titled "Guage Wiring". It was posted yesterday, in the "Outboard" section. It will solve your wiring mystery.<br /><br />To answer your other questions.<br /><br />1. There is a plug in the back of your control box, right below the key. That's where the tach. plugs in. You will need a harness. They are available from tach. suppliers.<br /><br />2. To cut a hole, you will need a good hole saw of the proper diameter. Tape the area well with masking tape before sawing. This will keep the splinters to a minimum.

 

[y2jericho]

Re: installing a tach

lol.. This is how i did it.. Got the dremel hooked up with a fibreglass reinforced cut off wheel.. Slowly cut out the circle as deep as i could. Then got the smallest drill availabable that was smaller than the cut off wheel in thickness and then where i cut with the cut off wheel i slipped in the drill and drilled through to the other side and i did it every 1-2mm.. Then you could push the circle in and it would fall out. And to get all the splinters and everything smooth and do small adjustments for the tacho to fit in i used the little drum sander on the dremel and turns out i didn't mark the hole properly.. No problem .. Just kept drum sanding with and gave the diameter about 2mm. The little drum sander also lasted very long.. Just had to use 1 so it was a $1 investment gone good

 

[dxdennis]

Re: installing a tach

WOW! A big "THANK YOU" to everyone for their <br />replies. I can hardly wait for spring so I can<br />get my boat out of storage and install a tach.<br />It's going to be a long winter...<br />Thanks again.