tach installation /speedo question

[jeffntanya]

I will be removing a tach and speedo from another boat. I want to install it to work with my 1981 johson 70hp. does anyone know where the tach wire hooks up on this engine? as for the speedo the sensor appears to be broken. can I buy just the speed sensor? does it have to match the speedo?

thanks,
Jeff

 

[jeffntanya]

Re: tach installation /speedo question

anyone?

 

[Lodgepole]

Re: tach installation /speedo question

On my 78 70hp there is a verical terminal block on the rear starboard side of the block. Gray wire is tach, purple is hot when engine is running, black is gnd. (to batt or block) Should also be same color wires to control box. I am told to set tach for this engine to 6 pulses/rev.

 

[es_bob]

Re: tach installation /speedo question

The speedometer has a deal (I think its called a pick-up) that mounts on the back of the boat that goes into the water. Its either air or water pressure that makes the speedometer move (at least in my boat), so the speedometer sensor would be the same ( I THINK ).

Something like this:
http://cgi.ebay.com/ebaymotors/Boat...019QQitemZ290142510729QQrdZ1QQsspagenameZWDVW

 

[iwombat]

Re: tach installation /speedo question

Grey wire is the tach signal wire. You'll need a 6p tach (or one you can set).

Speedometer goes to the pitot (or pickup, or pickup tube) usually on the transom .

 

[GlasV162]

Re: tach installation /speedo question

If your control box is new enough, it should have a plug on the end just underneath the ignition switch. OMC makes a handy wiring harness that plugs right into that on one end, and the other end has the 3 wires needed to hook up to the tach; it's a lot easier than running wires all the way back to your motor. Good luck.

 

[jeffntanya]

Re: tach installation /speedo question

thanks for all the replies! I think there is a rubber plug or something below the ignition. I'll check it out tomorrow when I go to the marina.

the tach I took off another boat has a dial on the back with numbers from 1 to 6. it was set on 4 for the suzukit dt140 that it was hooked up to. should I set it to 6 for this 1981 johnson 70?

 

[jeffntanya]

Re: tach installation /speedo question

ok I checked and it does have a 3 wire plug below the ignition. would the local dealer have a plug like this so I can wire the tach up? will the tach I took off the other boat work?

thanks