Dial-back Timing Light Compatibility

[SD_Targa]

Hello,

I recently discovered the advance curve on my distributor was completely off due to some aftermarket springs.  To make my testing / diagnosis easier I swapped out my CDI+ box for the original Bosch unit in order to use the dial-back feature of my timing light to accurately map the curve in situ.  Is there any way to adjust the CDI+ box to either eliminate the second spark or make it work with a dial back light?  I just got my distributor back from a rebuilder and want to confirm the curve.  It would be nice to not have to swap between boxes.

 

The CDI+ box was so nice to use during troubleshooting.  I was getting small exhaust after fires in the midrange at light throttle and I've chased my tail replacing every fuel and ignition component.  I finally realized my distributor was giving full advance (32*+) by 2500 RPM.  After using a dial-back timing light to plot my curve throughout the entire range, I was able to create an overlay to pull out timing in all the right places to basically bring it back into spec.  All the exhaust after fires disappeared and it finally ran the way it should.  I'm so glad I invested in the CDI+ box!

 

[Jonny Retrofit]

Thanks.   Haven’t had any issues caused by the second spark using that kind of timing light.  The sparks are so close together, the light can’t ‘see’ them.   
 

If the light has an RPM feature and that is reading correctly, then the second spark is not the issue. 
 

What is more likely is that the timing scatter is upsetting your view of the reading.  This occurs because the engine has no load so the box tries to compensate timing every ignition cycle.   When you are on the road this doesn’t occur.