You need an external tach gauge to calibrate (I have one built into my
dwell meter). Set it up where you can see it from inside the car.
Remove your tach, take it apart and there is a potentiometer on the back
of the electronics - i marked & drilled a hole in the case and covered
the hole with some electrical tape so I could adjust it in the future
without having to take the tach apart. Put it back in, but leave it
hanging out from the dash so you can get a small screwdriver around the
back and start the car & adjust so it matches your external tach. You
may not be able to get an accurate reading at both low & high values, I
opted for correct readings at the high range...
FYI you should be at 3270 rpm at 60mph in 1:1 direct drive (4th)
Skye
Word on the street is rsincla@interface-net.com said:
> Hey all,
>
> I've been following the posts on the speeds of our cars, and it got me to
> thinking. My speedo is jumpy (I know, probably need a new cable. It's on my
> list for my next Moss order), so I've been judging my speed by the
>tachometer.
> We figure in fourth gear, non-OD, 60 MPH is about 4500 RPM (At least, that's
> where we keep it to stay even with traffic) I know that's not right, because
>I
> remember seeing something like 18.xx MPH per 1k rpm, and my experience puts
>it
> at about 13.xx MPH/k RPM.
>
> Is it possible that my tach is reading low? If so, how do I fix it?
>
> Thanks in advance,
>
> Rory Sinclair
> '68 MGB Non-OD
>
--
1966 MGB - GHN3L Safety Fast! __,__\__
The MGB Experience www.mgbexperience.com (_o____o_)
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