Lotus Elan

How to Static Time a Pertronix or similar

PostPost by: Tahoe » Mon Dec 31, 2012 3:02 am

Decided to take a little time off the site to work on my car.

Here is a procedure I came up with to static time a Pertronix or similar system. I've been told this can't be done but it can.

1. Remove all plugs and position crank at 12 degrees BTDC or wherever you want set your static timing. I did this by simply placing my right index finger into the no 1 spark plug hole and rotated the crank clockwise with my left hand using a socket. You'll know your on the compression stroke when feel the pressure on your finger.
Lionel 001.JPG and


2. Insert the distributor and locate the rotor approx where you want your number one wire to be. Typically the distributor is positioned with the leads pointing toward the back of the engine, but they don't need to be.

3. Put the rotor and cap on the distributor but DO NOT connect any wires to the coil or spark plugs.

4. Using a multi meter set on ohms, connect one lead to the number one spark plug lead and one to the high tension lead.
Lionel 011.JPG and


5. Rotate the distributor until you see the needle move to infinity, and you know you have the rotor aligned at 12 degrees BTDC and you have static timing.
Lionel 012.JPG and


6. Connect all leads and wires to the coil, start engine, and adjust timing as desired for your application.
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PostPost by: twincamman » Mon Dec 31, 2012 3:24 am

BRAVO good to see that someone is thinking ---brilliant --I will introduce this to the f 2000 car at the shop ---ed y
dont close your eyes --you will miss the crash
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PostPost by: billwill » Mon Dec 31, 2012 3:32 am

As an electrical engineer, that doesn't (at first sight) seem to make any sense whatever to me!

You appear to be measuring whether or not the rotor arm touches the number 1 spark plug contact, which on most systems it is not supposed to do anyway.

From the website:
http://www.pertronix.com/prod/ig/ignitor/default.aspx
It would appear that the Pertronix is a hall-effect replacement for the points in the distributor and does not (directly) effect the rotor arm and the distribution of the spark to the appropriate plug. In such systems the spark jumps across the small gap between the rotor arm and the contact leading to the spark plug, without actually touching it. Also in the typical distie on a Lotus twin cam the rotor arm has quite a long contact 'leap' area covering at a guess at least 10 degrees of the 360 degree rotation. This is so that provided the contacts open within that 10 degrees the arm is still near the plug lead contact.

I would be more inclined to try a much simpler technique and connect a low power 12v light bulb between the earth end of the spark coil and the 'earth' of the metal of the engine. Then remove the spark plugs but connect their leads to the tops of the plugs and earth the cases of the spark plugs to the engine. (this latter action is to present normal conditions to the coil so that it does not generate excessively high voltages and back emf which might damage the electronic ignition).

With normal contacts, with the ignition on, when the contacts are closed there will be no volts across the bulb so it will be unlit. When the points open the voltage will be there and the bulb will light up. So you can twist the distie in the appropriate direction until it is just at the position where the bulb lights up.

Now this should be more or less the same with the hall-effect sensor and it's solid state switch, but it may well be designed so the the simulated contacts only stay open briefly. In this case the light bulb may flash once as you twist the distie. The snag is that the flash may be too brief to notice it.

~~~~~~~~~
You could use your multimeter on volts instead of a lightbulb, but the backemf kiick from the coil might damage it. Light bulbs are cheaper.

You can see some of the voltage spikes produced in the PDF file in this topic.
elan-f15/using-oscilloscope-for-engine-diagnostics-t20967.html
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36/6725 S3 Coupe OGU108E Yellow over Black.
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PostPost by: Tahoe » Mon Dec 31, 2012 4:16 am

Bill,

I'm not an Electrical Egineer, but it worked. You are right, I'm only finding when I have continuity from the high tension lead, through the rotor contacting the no 1 lead. I did rotate it slightly more after contact and the timing was actually very close, and it started right up. Maybe not the best way to do it, but it seemed logical when I tried it.
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