<VV> Failed emissions test

[D. Monasterio]

     Last week (finally) installed the rebuilt engine (110) on my new toy (64 Deluxe GB). It started at first attempt with the usual valve clattering for a couple of minutes, then smooth running. Got it running for about 2 hours (oil and filter change at first half hour). Did a final tune up with new 8mm wires, 7502 plugs at 0.035", Pertronix, 10degrees advance, cleaned and calibrated carbs (floats at 1 1/6"). Fuel pump is a mechanical.
     It runs smoothly on regular gas at 4,500ft altitude so, I decided to take her for the emissions test in order to get her new Mexican license plates. It failed !! 
     The maximum allowed HC is 300 ppm and CO is 3.00 % but the brier's engine couldn't be put on less than 480 ppm (HC)with the 3.00 % on CO.
     Didn't have this trouble with the 140 HP engine in the 67 cpe. (25,000 miles) nor the 110 HP engine in the 62 Rampy (12,000 miles).
     What could I have made wrong ?

     As always... Thanks in advance.

     Daniel Monasterio