Can anyone confirm the right tach settings for a 1976 70 HP Johnson

[eavega]

Hey folks. Boating season is upon us in the South. I took my boat out on the lake for a shake-down and water test after having installed a new power pack at the end of last season. Everything worked great, except the tach was reading very high (but consistent i.e. the gauge responded accordingly and did not jump around.). Now, I think I would know if my motor was running at 7K RPM versus its usual 5200 at WOT. Also, the GPS speed was the usual 35 MPH so I am suspecting the tach somehow got out of calibration. I have to admit it was a cut-rate no-name tach I bought online a couple of years ago, but until today it had performed flawlessly.
Before I go and buy a new tach, can anyone confirm what the right Pulse/Pole settings are for a 76 70 HP Johnson (3 Cylinder). Unfortunately the Faria application guide sheet only goes to 1977. Also, is it possible for a tach to simply get uncalibrated? I did notice that the faria tachs have a POT which I would assume is for small calibration adjustments.
Thanks in advance for any replies.

Rgds

 

[boobie]

Re: Can anyone confirm the right tach settings for a 1976 70 HP Johnson

6 pole. If the tach was working before and you still have the same pole setting and it's now acting up, I'd say you have a bad tach.

 

[eavega]

Re: Can anyone confirm the right tach settings for a 1976 70 HP Johnson

Thanks for the info Boobie. Since the tach was responding correctly, just high, I assume it got out of calibration somehow. I guess you get what you pay for. I went ahead and replaced it with a Faira 7K tach, and that one is spot on with my optical test tach. If that is the worst of my boating problems this year, its gonna be a great summer on the water!

Rgds