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<p>Where are the coil and CSI picking up their 12v supplies from?</p>
<p><br>
</p>
<p>The RVI tach is current triggered and wired from the ignition
switch (not the fusebox) though a pick-up on the tach to the coil
+ve and pulses through the coil register on the tach.</p>
<p><br>
</p>
<p>Prior to 1973 and the RVC tach electronic ignition systems
usually needs to be powered from the white at the fusebox as the
additional current from the electronics flowing through the tach
pickup can cause problems. However they usually read too high in
that case.</p>
<p><br>
</p>
<p>FWIW RB cars with ballasted ignition systems also need electronic
ignition to be powered from the white at the fusebox even though
they have an RVC tach as the coil +ve is continually switching
between 12v and 6v and that can confuse the ignition system.</p>
<p><br>
</p>
<p>But it sounds like the problem may be more with the tach itself,
they can be tested if you have an old-fashioned trickle charger as
described here <a class="moz-txt-link-freetext" href="http://www.mgb-stuff.org.uk/gauges.htm#tachtest">http://www.mgb-stuff.org.uk/gauges.htm#tachtest</a></p>
<p><br>
</p>
<p>PaulH.<br>
</p>
<p><br>
</p>
<p><br>
</p>
<p><br>
</p>
<p><br>
</p>
<div class="moz-cite-prefix">On 09/06/2023 10:24, R. Martin Rogovein
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:830cd1fa-bab1-6c05-70ef-7cd1f6ec80d5@bezeqint.net">
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<p>Hey all, <br>
</p>
<p>After 15 years of staring at it in it's parking space, I am
almost done with a full mechanical restoration of my 70 B.</p>
<p><br>
</p>
<p>Engine, overdrive, brakes, steering, suspension, carbs, and
more all completely rebuilt.</p>
<p>Loads of new parts.</p>
<p><br>
</p>
<p>No paint and bodywork yet, but I'll get there.</p>
<p><br>
</p>
<p>Replaced the points ignition with a CSI electronic unit, wired
everything up per their diagram.</p>
<p>Car runs great, but the Tachometer registers nothing.</p>
<p><br>
</p>
<p>the tach is the RVI unit with three connectors (M and F bullets
for 12v from fusebox through tach to coil) and a tongue for
switched 12v to the electronics. Ground is though one of the
mounting bolts.<br>
</p>
<p><br>
</p>
<p>Is there a wiring trick to get this tach to work with
electronic ignition, or do I have to either get a later tach or
order one of the conversion boards?</p>
<p>(like this <a class="moz-txt-link-freetext"
href="https://spiyda.com/smiths-rvi-rvc-conversion-board.html"
moz-do-not-send="true">https://spiyda.com/smiths-rvi-rvc-conversion-board.html</a>)</p>
<p><br>
</p>
<p>thx<br>
</p>
<pre class="moz-signature" cols="72">--
--------------------------------------------------------
Israel is the most dramatic country in the world.
Everybody's engaged. Everybody argues.
When I leave Israel, I get a little bit bored, you know?
--Shimon Peres
--------------------------------------------------------</pre>
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