Also, DO NOT TRUST these delay timing lights too far. Sometimes something like a reluctor which is just slightly misadjusted can cause a multi-fire condition in an ECU, or the light itself can be dodgy, and give false readings.

I recommend ONLY that you take the time to scribe the wheel or get an accurate timing tape and CHECK the marks with a dead stop, very easy to do.

MANY of these guys will post "I've never had trouble," or "MY light is accurate" but the fact is, you may not know for sure whether it is or not--all the time.