Timing scatter, blurred strobe

[jamwoirs]

Hi,
This does not seem to be a common issue from looking at the forum, and it also seems little discussed unless Ive missed it.
I have a possible problem with timing scatter, unless Its my timing light! Simple old style lights seem to be recommended elsewhere for EDIS - what,s the opinion here?

I have my crank pulley (trigger wheel attached to un-dampened part) marked out with degrees BTDC 0,15, & 34 degrees for ease of setting. No slack in pulley or trigger wheel or sensor, everything set up exactly as recommended.

When checking the timing with a strobe light, the timing marks are a blur, scattering by approximately 4 degrees, or 6 mm visual width. This is fairly consistent too.

I of course expect spot on timing, not the sort of wobble you get with an old distributor, so am convinced something is amiss!

It is not the Megajolt unit, nor interference on the pip & saw wires as I've tried it with magajolt off, just on the EDIS 10 degrees, and also tried disconnecting the pip and saw, just in case. Megajolt seems to be doing its job when connected and nothing unusual happening here.

I've tried a new and separate sensor wire (shielded, connected one end only at EDIS pin 7)
I've tried a new sensor
I've tried a new coil pack
I've tried new HT leads
I've tried a different EDIS unit although second hand!
I've checked all wiring
I've checked the plugs (Denso irridium) seem fine and one is new.

Its an A series engine running 11:1 on LPG (propane), but same effect on petrol. It runs well although idles a little rougher than I'd expect from its cam etc. It running well, of course, is never good enough if better is achievable!

The timing light is a simple old fashioned orange in line jobby connected to no 1 cyl. plug

The only thing which seems to make a difference is if I take the HT lead from no 4 cyl (sparking from the same coil) and hold it at a distance from the plug, such that the spark is still jumping to the plug but having to jump a fair way - the further away I move it the less the timing blur occurs. Perhaps a clue lies in this?


Has anyone else experienced blurred timing with a strobe/ timing scatter with their EDIS set up?
Any advice would be much appreciated.

Thanks

Jamie

[brentp]

I would definitely try a different timing light. And verify it with and without the Megajolt connected, as well.

[jamwoirs]

Brent, Yes, turned out to be the timing light. Thanks.
Not that I wish to endorse any particular product but the Accuspark H8000 worked just perfect, nice bright white visible strobe showing timing marks on crank pulley perfect. Old Gunsons orange one just not behaving!

Next project to have a full throttle richening device using the user outputs on MAP & rpm activating a Purge valve plumbed in as an extra supply between my LPG mixer and somewhere? . Ive a BLOS LPG carb which annoyingly runs lean at WOT below 3000rpm no matter what, so fingers crossed this useful extra on the MegaJolt may solve this.

Many thanks