Tachometer hook up

[bgred71]

Hello every one ,

Can some one point me in the right direction? I am installing a 1964 85HP merc six cylinder inplace of a 1979 80HP merc four cylinder, I have controls for both motors that include wiring harness will i be able to hook up the tachometer to the six cylinder some how using a comonation of both controls? and if this is possible hhow do I go about it?

Thanks Anthony

 

[Chris1956]

Re: Tachometer hook up

The wiring is not an issue. However, the '79 motor takes a conventional tach. The older motor may take a Merc-specific tach, since it has points and coil ignition. It is best to see an (old) dealer.

 

[Laddies]

Re: Tachometer hook up

It's very simple to tell if you check the 79 85HP and the rectifier should have a brown or gray wire hooked to one of the posts with a yellow as it should have, then you may hook the tach to the rectifier on the 64 850 and it will work fine. The last year the factory installed the CD powered tach was 1975 but you have to check as some dealers got ride of old style tachs by moving thr brown wire back to the switch box.

 

[bgred71]

Re: Tachometer hook up

Thank you for the info. I looked at my 1979 80HP and there is a brown wire from the internal harness that is hooked to a little black block ( is that the rectifier? ). Also I noticed on the 1979 80hp that the internal harness is a 6 pin while the external harness is a 7 pin. Do i have the right tach for the older 6 cylinder?

 

[Laddies]

Re: Tachometer hook up

The harnesses are differant for the 2 engines so they will have to be corrected but the tach will work fine if you connect it to the rectifier (the little square box)