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GreenSwede

Setting Timing. Pertronix. Eng. Off/test Light Version?

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(edited)

Another timing-question. Or rather a set-the-timing-with-pertronix-question. Again.

 

I had the dizzy off for a check in bench and some work done. The man with the bench could´t check it in bench with the Pertronix installed, so I put back the points and condenser. 

 

When I reinstalled the dizzy (with points) I used the test light way of setting timing. The flywheel on the mark - a test light between positive on battery and the condenser/points connector. Turn the dizzy until the light goes out. Turn engine past the mark on the flywheel and check that it goes out on the spot. Which worked fine.

 

Now the Pertronix is going back in, and due to my oh so sporty strut bar and a few other things I could not for the life of me get the condenser off without rotating the dizzy - setting the timing off again. I did notch it with a mark, but I don´t trust marks. Or myself.

 

So, the question:

Is it ok to do the test light version with the Pertronix installed, or will I fry something (the Pertronix)?

 

It just might be at very stupid question, boarding on paranoia, but I am very, very tired now and thought I´d check.

Edited by GreenSwede

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You need to reset the timing after installing a Pertronix, even if you didn't move the dizzy. I would not using the test light method to reset, as you may fry the Pertronix. Just use the notches you marked as a guide. Fire it up and use a timing light on the flywheel ball method.

HTH Beaner7102

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You are not going to hurt the petronix by having the timing off. Get a proper timing light and set the timing after you put the Petronix in. Use your marks as a starting point.

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If you are concerned about using test light method, you could use #1 plug wire with spare plug. You should get spark as #1 reaches TDC on firing stroke. That's close enough to start motor. Basically, regardless of points/pertronix, rotor should point to #1 wire on cap with engine at TDC, #1 firing position. Then use timing light.

  1. With test lamp, light should come on as motor passes TDC

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(edited)

It´s fired up, using my mark on the foot of the dizzy. I have a timing light and will do it that way come weekend. After I put the wide band sensor in. I installed a 38 this fall and haven´t even touched the idle screws. Runs well, but a bit too well when cold, so rich. After having the dizzy off, it first fired up and idled but would fall down to 3 or even 2 cylinders on throttle. Checked the plugs, and they were totally black.

So I´ll check timing and mixture very soon. With new plugs.

 

Anyway, why I wanted to do it the test lamp way was cause I spoke to an old BMW-mechanic. He served ´02's when they were new and shiny. He said they got specific instructions to set the timing COLD, and by using a lamp and the mark on the flywheel. According to him the germans were very clear, in a very german manner, that it was the ONLY way it should be done. And then it was not to be touched. Checked to see the curve, yes. But not touched. I got curious and thought I'd try. Bygones.

 

And, if knowing the specifics of the Pertronix sensor it shouldn't be a problem using that and the mark. But I don´t know the specifics, and I´m not curious enough to dig in it. I just want to drive.

 

Anyway, thank you for the replies!

Edited by GreenSwede

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Regarding frying the Pertronix, further explanation, if you leave the ignition on without the motor running for an extended period of time you can fry your Pertronix, not sure how long, but couple minutes is plenty of time for it to fry, so using the timing light method is probably not a good idea, use the marks, or heck even if you can start it and get it to run, then use a timing light to set the timing right, Isn't the timing mark on the flywheel method set the idle up to 1500 rpm and the mark on the flywheel should line up with the hole with the timing light, but don't remember if that is vacuum advance connected or disconnected, I remember reading a post about it here not too long ago.

 

Someone will remember, and or correct whatever I have said (best way to get a response on a forum isn't asking a question, it is saying something controversial or wrong) or someone will point you to the link and joyfully point out that all you had to do was a simple search and the information would have come right up  ;)

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I work on Porsches and BMWs for a living, and while this has only been for the last 10 years or so, I am well versed in the German notion of "we are always right, there is only one way to do it properly" that is espoused by both manufacturers. This is often sage advice, though it sometimes isn't.

 

Ignition timing should always be set at normal operating temperature since that is how the engine is designed to be run and how you will be driving it. I could see that back in the day, it may have been that the "perfect" base timing setting was optimally achieved when the engine was cold.  When the 2002 was brand new and serviced by the dealership, there was minimal wear to engine and distributor components and this setting could be reliably achieved.

 

Fast forward 40 years, and there are a large amount of variables when considering the ideal timing setting for an individual M10 engine, or any other old engine for that matter. Mechanical lash in the distributor/drive, myriad distributor part # supercessions and rebuilds, differing compression ratios and ignition setups, differing fuel octane level and composition, etc, etc. Not to mention that we have nice modern digitally adjustable advance timing lights versus the classic static strobe lights of yesteryear.

 

You did well by having your distributor properly checked on a testing machine. Invest in a proper timing light and set the timing based on your particular distributor/compression ratio and ignition system setup/fuel octane level, using the factory advance curve of your distributor as a starting point. I have seen that the dwell setting of a Pertronix conversion is not always exactly the same as the original breaker point setup, and the timing may need to be adjusted accordingly.

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