I think I may have mentioned before that I have a MSME from the University of Wisconsin Engine Reseach Center where I did emission related research, so I have an indepth understanding of emissions generation and control.

The simple act of retarding initial timing is very effective at reducing emissions readings, and can often turn a marginal failure into a solid pass.
I only wish we could do this for M103 engines being as how they are often on the ragged edge of the HC limit and California has identified them as "high emitter profile". Unfortunately, the electronic timing control system built into the EZL ignition module does not allow the initial timing to be adjusted.

Duke