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@ix.netcom.com[SMTP:dondaves@ix.netcom.com]
>Sent: Wednesday, January 15, 1997 6:13 AM
>To: tigers@autox.team.net
>Subject: Re: Electronic Ignition
>
>STUART_BRENNAN@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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