Failed Emissions, high HC #'s Options

[MarkV]

What is the relationship between advanced timing and HC?

2056 with Dellorto 40's, new cap, rotor, wire, no points 050 dist. Timing set at 27 DG at 3200 RPM, 4 DG at idle, idle set at 900 RPM. mixture screws set at 1/2 turn out from lean.

Test results are:

Idle Test: 835 HC with a standard of 400 HC PPM.

4.18% CO with a standard of 3.5% CO.

Cruise Test: 1118 HC with a standard of 400 HC PPM.

4.74% CO with a standard of 5.5% CO.


So should I retard the timing to 0 DG at Idle and set the mixture scews lean or ??????

What else will cause high HC? In years past the HC has been as low as 90 PPM. Can't figure out what is wrong with it. Seems to run fine. Double checked valve lash & carb sync.