using a timing light with megajolt

steve_c · Post by **steve_c** » Fri Jul 18, 2008 1:36 pm

I have a timing light with settable advance. I've a feeling that these will be confused by the wasted spark system used with Megajolt. I assume the timing light measures time between each spark and therefore can determine fractions of a rotation. If there are now two sparks per cycle instead of one this will make any set in advance out by a factor of two. If this is the case, for an advance of 10 degrees should I set 5 or 20 degrees into the timing light?

luke6040 · Post by **luke6040** » Fri Jul 18, 2008 2:13 pm

I may be wrong but....i think the edis sends out a postive and negative spark and the light will only pick up on one of these?
Sorry if this is totally wrong lol.

Dimbit · Post by **Dimbit** » Fri Jul 18, 2008 4:59 pm

Set it to zero. It's not worth the hassle. Put marks on the trigger wheel and go off that.

TwoSheds · Post by **TwoSheds** » Fri Jul 18, 2008 9:02 pm

luke6040 wrote:I may be wrong but....i think the edis sends out a postive and negative spark and the light will only pick up on one of these?
Sorry if this is totally wrong lol.

Sorry, but all sources I have seen say that EDIS polarity is always the same way no matter which is working and which is wasted so when sparking, one lead will always go positive with respect to the vehicle ground and the other will always go negative. This is why (my theory anyway) the strobe only works on two of the four leads on the coilpack.

As for a settable advance strobe not working with a wasted spark system, that's a good point worthy of thought... Another sleepless night methinks...
(Glad I still use my old basic one...)