? Timing Light Myths ?

[JCT]

I have had several people tell me different things about using timing lights on MSD Ignitions. Lets hear myth busting facts.

Adjustable timing lights... will they work or not?
Non-Adustable timing lights... are they the best suited?

We recommend using non-adjustable timing lights because of their analog circuitry design. Adjustbale digital type lights tend to pick up interference from the MSD and can be off as much as 1 degree per thousand RPM.

[JCT]

Thanks very much for the reply. Maybe this will settle things around here!

Jay

[Lazarus]

I think there may be a more specific answer to the question about digital timing lights. Some of us have inquiring minds and want to really know what the deal is. I doubt if one type of light is more likely to pick up interference than another. What is far more likely is that at idle, a CD ignition puts out 8 sparks or so. Digital lights may start triggering on any one of those 8 sparks erratically causing the mark to jump all over the place. Analog lights are more likely to see the cumulative effect of the spark group as the trigger signal. One manufacturer even offers a tune up feature on a CD ignition that tells the unit to only output one spark per cylinder just so that any light will give good results. Besides, the real reason for owning a dial-back timing light is to check your distributor advance at high RPM. Normally you would not have timing marks out past 10 degrees or so. If you are not running a vacuum or mechanical advance distributor, or don't want to monitor your spark advance at high revs, save your money and get a standard light. Hope that clears up a few questions.
-Lazarus