how can i tell if my Tach is accurate?

[tigerfishes]

it seems like my tach is over reading rpms. how can i check this.
it's on a 1977 19' Century with a 190hp OMC 302 ford. just put new wires, plugs, cap rotor, points and now it seems like i'm not getting as much speed out of my rpms. doesn't sound like it's running the same speed either. i used to max out at about 5500-5600 and now i can burry it at 6000 and keep going faster. cruises at 5100 at 28mph and temp stays at about 130-135... which it used to do at about 3000 rpms...

thanks

 

[Bondo]

Re: how can i tell if my Tach is accurate?

how can i check this.

Ayuh,... Swap in another tach, or hook up a shop tach...

5500rpms will kill that motor,... 4800 should be about Tops...

 

[sethjon]

Re: how can i tell if my Tach is accurate?

Sounds like you need a new tach. I doubt it ever got up to 5500 and if it 6000 it would probably blow up.

 

[LAC_STS]

Re: how can i tell if my Tach is accurate?

I took my tach to a local Marine surplus store. they have a bench test thing for gauges. I imagine other places will have one also.


they hooked the gauge up and go through all the settings from 1K RPM to 6K and if the tach doesnt do it then its shot.


Mine wouldnt get above 3200 RPMs even when set to 6K.

They gave me a new one and showed me that it didi it all correctly.


So I would try to find somewhere to test yours if you dont want to buy a new one. They arent that expensive either way.

 

[lonesouth]

Re: how can i tell if my Tach is accurate?

Any idea if west marine has that ability to test?

 

[picklenjim]

Re: how can i tell if my Tach is accurate?

I don't know of any West Marines testing tach's. Here's a tester you can get from Harbor Freight.http://www.harborfreight.com/digital-photo-sensor-tachometer-66632.html
All it's going to do is tell you it is not accurate and you already know that soooooooo you might as well just get a new tach.