HC levels on emissions test.... PASSED, good ole Metro Nashville Options

[malcolm2]

'75 1911 L-Jet with about 7000 miles on it, and a fresh oil change this week. Fresh injectors before the first test. Probably running 87 oct E10 gas today. Might have been 93 100% last year.

12 months ago I passed the state county sniff test here are the results from 10/2013:
HC 399 limit 500
CO 0.65 limit 5.0
CO2 11 no limit listed

and from just moments ago 10/2014:
HC 428 limit 500
CO 3.83 limit 5.0
CO2 11.53 no limit listed

2 different inspection stations, not sure if that matters.

The CO seems to have jumped. I did tweek a few teeth on the AFM between the tests. IIRC I have moved it 9 teeth.

Plus the HC is getting close to the limit. I can't remember the RPMs during either test, but they tend to be about 1000, a bit high.

It passed but I want to be pro-active, any thoughts about the CO jump and pulling the HC down for next year?

Clark

[Cap'n Krusty]

I would think that adding some clearance on an engine normally running zero clearance would work just fine. IME, the .006" clearance remains pretty much the same as the engine comes to operating temps, so adding .010-.012" should make a similar change in HC emissions. Not gonna hurt anything for the short time you're running it that way. I usually run the tank low and add only 4-5 gallons of regular, not a full tank. You really need to set the AFM with a CO machine ...

The Cap'n