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Re: Electronic Tach

To: DANMAS@aol.com
Subject: Re: Electronic Tach
From: Peter Lucas <pllj@earthlink.net>
Date: Thu, 30 Oct 1997 23:31:06 -0700
Cc: triumphs@Autox.Team.Net
References: <971031111006_474105133@emout07.mail.aol.com>
DANMAS@aol.com wrote:
> 
> In a message dated 97-10-31 07:19:40 EST, egil@kvaleberg.no writes:
> 
> > On 31 Oct 1997, Joe Curry wrote:
> >
> >  > One lead goes to the coil negative connection
> >  > One goes to Ground
> >  > The third goes to Power and the voltage stabilizer.
> 
> To which Egil replied:
> 
> >  The trad. 70s Lucas electronic Tacho is connected in *series* with the
> >  coil. So it requires that the connection between the coil and the points
> >  is routed *via* the tach. So you need two wires for this. The standard
> >  connectors at the tach are such that it is easy to connect them should you
> 
> >  ever need to remove the tach for servicing etc. Failing to do that will
> >  cut the ignition if you remove the tach.
> >
> >  In addition to these two wires, you need a supply and ground wire, as you
> >  noted. Plus a wire to the instrument lighting, of course.
> >
> >  > You always have theoption of an after-market one.
> >
> >  They will usually connect as you have noted, with ONE wire to the coil.
> 
> Egil:
> 
> Lucas also supplied the type tachometer as described by Joe. The type you
> mentioned was used in MGBs, while the other type was used in Spitfires (at
> least in the later years).
> 
> There is one error in what Joe said about connecting a tachometer that needs
> to be corrected. The tach should NOT be connected to the voltage stabilizer
> that supplies the other gauges. First of all, it is not required, as the tach
> has its own internal regulation. Secondly, the existing regulator is designed
> to provide the correct output voltage with a specific load, based on the
> gauges which were installed by the factory. Adding another gauge will change
> the output voltage, making the gauges read even less accurately than they
> already do. The voltage will be lower, making the gauges read less than they
> should.
> 
> Dan Masters,
> Alcoa, TN
> 
> '71 TR6---------3000mile/year driver, fully restored
> '71 TR6---------undergoing full restoration and Ford 5.0 V8 insertion - see:
>                     http://www.sky.net/~boballen/mg/Masters/
> '74 MGBGT---3000mile/year driver, original condition
> '68 MGBGT---organ donor for the '74

So what you are saying then is-
Make a connection to the:       Coil
                                                        Ground
                                                        Power ONLY
Is it OK to cap off the extra wire or is there somthing i'm missing?
Thanks 
PL

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