Jay,
I tried to reply earlier, but it didn't seem to get out so here is another
try.
Calif (at least two years ago) used to measure two emissions: Carbon Monoxide
and Hydrocarbons. Didn't measure NOx. The measurements were done at idle
and at some higher RPM (2.5 to 3 k or there abouts).
CO output is a function of the air/fuel mixture. So is the hydrocarbon
output but in a reverse function. When the carbs are adjusted for near
stoichametric (I KNOW I mispelled that one) CO and Hydrocarbons due to
combustion are near minimal. In addition to the hydrocarbon coming from
burning gasoline, there is also the output due to burning oil (usually
primarily due to oil getting past the vavle seals and guides but also past
the rings).
So what does this mean for the test ? Get in a near perfect state of tune and
adjust the carbs.
State of tune: any malfunction of the ignition system (points, distributor
scatter, ignition wires, plugs) increases the chances of misfire. As you can
well imagine, a misfire sends an unburned charge of gas/air down the pipe.
Pure unburned hydrocarbons - fail test. Adjust timing per factory specs.
The CA test requires this, and the tech will(should) set this before the
test and might even charge you for a "low emissions tuneup" to do so if it is
not. I doubt that different heat range plugs will make any difference, the
test is not run onder load.
Carb adjust - likely to be the single biggest variable affecting your ability
to pass the test. Note that any vacuum leaks (hoses, gaskets, throttle shafts
worn in bushings) can dramatically change emissions. I once failed a test,
the technician wrapped a shop rag around the throttle shaft and wet the rag
with carb cleaner and the car passed. If you have Stomberg 150s with worn
shafts, maybe heavy grease applied to the shaft/bushing area just before the
test could help.
I have heard that clean (fresh) oil can help, it couldn't hurt. I doubt that
viscosity makes any difference.
Make sure that the PVC valve is working.
Good luck and I would like to hear the results.
-Roger
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