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Re: Tach Problems

To: MG Nuts <>
Subject: Re: Tach Problems
From: Skye Poier <>
Date: Tue, 13 Aug 2002 15:24:25 -0700
It's not really clear what the original problem was, or how it was
fixed.  The 66 tach has a loop of wire behind it, which is opened and
closed in series with the points (distributor), and is looped at a
certain size and at a certain angle so as to drive the tach by
electromagnetic induction.  If the loop is incorrectly sized or placed,
maybe that would cause an errant reading.  If all else fails, there is
a potentiometer inside the tach which can be adjusted.  Does the tach
read 500 rpm lower through the entire range (linear) or does the
difference change with rpm?

66 B

Word on the street is Phillip Erikson said:
> Hi, MG-Listers. After a recent dash R&R on my '66 B, I noticed the tach making
> some wild gyrations and then finally quitting. When I took it to a good
> electric shop, they said there was no wire hooking it up, so they ran another
> wire to the negative terminal of the coil. The tach worked again but it's
> reading about 500 rpm lower than it did before the R&R.
> Any idea what's wrong?
> Phil Erikson

1966 MGB - GHN3L     Safety Fast!             __,__\__ 
The MGB Experience   (_o____o_)

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