Tachometer

bkair

Member
Joined
May 2, 2007
RO Number
26118
Messages
42
I have faria 6000 rpm tachs that both operate. The issue I have is that one of them reads higher rpm when the engine starts but when I tap the glass face the needle drops to proper rpm. Anything I need to look at or just tach getting old?
 
My guess you'll have to replace the gauge... To double-check it swap it with the other one.
 
Check the back of the gauge for a slot where a screwdriver might fit in to change the tack for use with 4, 6, or 8cyl engines. If you have that then put a screwdriver in the slot and twist it back and forth a few times and finish on the proper setting. That sometimes takes care of the problem. I have to do it to one of my tachs every year or so.
 
That...and the "Faria tap"....not exclusively a Faria service bulletin item, as many other manufacturers need the same kind of "love tap". As JVM said, the cylinder selection screw on the backside of the tach often will correct the issue...as the tach ages, the more frequent "adjustment" may be necessary.
 
And if you have an hour meter on the tach, you'll lose info on existing engine hours.

If the tachs have been adjusted once, I haven't found the gross and fine adjustment screws on the back to be useful. The "tap" seems to work for a while... until it does altogether.

The tach is accurate at one point of the engine's RPM range. Mine happens to be semi-accurate at 2000 RPM, not so much at idle or WOT. Faria's rebuild program is a decent deal, but you still end up with an analog tach that's only generally accurate.

Check out digital tachs by Aetna Engineering. I'm probably going to switch when I get around to it.

-Chris
 
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