I had this problem in my Citroen BX - I bought an electronic tach
afterwards, and it displayed either correct rpm or double rpm, depending on
rpms and on weather. I put biggest resistor I could find (n x 100 x kohm)
to the tach cable, and it works quite well - problems occure only when it
rains...
Larry, Finland
> The Unilite Electronic ignition system sends out the normal signal of
>open and closed ground circuit to the coil. Systems that use Ignition
>amplifiers and /or other smart boxes "may" not. If they are a standard
>single fire ignition module, then the lead to the coil should still
>operate the tach, because the tach expects to see only two fire per
>revolution (Alpine), or four fires (Tiger) per revolution. Multi fire
>ignition systems like MSD fire multiple time once triggered. About 17
>degrees of rotation, which is about the time the points stay open. Once
>the points close, the MSD box resets and recharges the coil for the next
>fire. When they rapid fire during that 17 degrees, it very quickly
>charges and fires the coil which the tach will see either as noise, or
>VERY high RPM. Because this firing isn't constant... ie bursts of 17
>degrees of rapid firing, followed by no firing......the electronic
>tach's do not display the correct RPM, if they function at all. With
>MSD's, the tach source MUST be from the points or unilite coil lead
>BEFORE it goes to the MSD box.
>
>Unilite are great!
>
>Rich
>
>
>>----------
>>From: dondaves(at)ix.netcom.com[SMTP:dondaves(at)ix.netcom.com]
>>Sent: Wednesday, January 15, 1997 6:13 AM
>>To: tigers(at)autox.team.net
>>Subject: Re: Electronic Ignition
>>
>>STUART_BRENNAN(at)HP-Andover-om3.om.hp.com wrote:
>>
>>>I'm quite sure that the stock tach won't work with a full electronic
>>>ignition swap, but what about these "points replacement" devices that
>>>have been mentioned recently? Do they effect the operation or
>>>accuracy of an unmodified tach?
>>
>>>Stu Brennan
>>
>>I'm running the Mallory Unilite with a Mallory coil and my tach works
>>just fine.
>>
>>Don Daves
>>
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