Dale
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| posted on 25/5/10 at 01:25 AM |
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mgb smiths tach
I have been looking to see if I can get my smiths current sensing tach to work with my ford engine (tfi ignition).
Any hints, the tach is a rvi 1439/00a
Thanks
Dale
Thanks
Dale
my 14 and11 year old boys 22
and 19 now want to drive but have to be 25 before insurance will allow. Finally on the road
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Canada EH!
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 posted on 25/5/10 at 01:33 AM |
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If it is the tack I think it is, it runs off the coil. There is a company in New York called Nosinger or similar who can convert it to run on a
computer controlled engine.
They also rebuild all Smiths and Jaeger instuments.
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02GF74
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| posted on 25/5/10 at 07:31 AM |
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is it negative or positive earth?
negative earth: for current sensing tacho there will be a wire that that wraps anti-clockwise round a plastic former - this is the single turn of the
primary transformer.
positive earth is other way round.
one end of the wire connects to the ignition switch, goes as described above, and to the ignition coil.
there will be two tabs - one insulated for the power and other is earth to the tacho - again you need to check if it is positive or negative earth;
the former you would need to swap 2 wires inside.
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IanBrace
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| posted on 25/5/10 at 08:59 AM |
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02GF74 If this is correct what difference does it matter whether it's wrapped anti or clockwise? Also should it not be the wire from the trigger
of the distributor (either elec or points) to the coil that is wrapped. It's this wire that pulses whereas the ignition live is constant?
I only ask because I'm using a Smiths tacho too......
www.aerialphotography.org.uk
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MikeRJ
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| posted on 25/5/10 at 10:36 AM |
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The trigger wire will only be carrying a very small current, nowhere near enough to operate the Tacho. Either the feed wire to the ignition amplifier
or the wire between the coil and the amplifier should be used, but there is no guarantee that these old current sensing tachos will work correctly
with modern constant energy ignitions.
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02GF74
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| posted on 25/5/10 at 02:33 PM |
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the direction of wrapping will determine the polarity of the pulse.
here, I am not making this up
AFAIK putting the tacho between igntion switch (12V) and coil or coil and points should not make a difference
since the tacho operates on change in current in the wire. MG may have wired it that way to use shorter wires perhaps?
 
Rescued attachment tacho.JPG
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