From: doctorduke_REMOVE_505242_THIS_@yahoo.com
Botton line - PASSED!!!
To review, California uses an "acceleration simulation mode" (ASM)
test at 15 and 25 MPH. The load for each speed is greater than the
load to maintain these steady speeds, and this simulates
moderate acceleration, but the tests are actually conducted at the
two steady speeds. The 15 MPH test is conducted at a higher relative
load than the 25 MPH test. I believe most areas of the country that
do loaded mode testing use a procedure called I/M
(inspection/maintenance) 240. I'm not familiar with this test
protocol, but if anyone understands it, I'd appreciate a rundown.
As I expected, the reduced valve overlap increased NOx - 605/479 ppm
for the 15/25 MPH tests respectively, about double the test results
from two years ago, but this only placed my car at about the average
NOx level (554/468 ppm) for my year group (75-80) and 44/39 percent of
the maximums of 1364/1224 ppm.
HC went up slighly, but CO down. HC in ppm was 22/27 versus 18/11 two
years ago. The average for my year group is 47/37 with limits of
218/181. CO in percent was 0.01/0.00 versus 0.03/0.01 two years ago.
Averages for my year group are 0.20/0.17, and the limits are
1.36/1.16.
I expect the mixture might have been a bit lean leading to some slight
combustion instability. Slightly richer might have reduced the HC
back to the teens or single digits at the expense of a slight increase
in CO. Free oxygen was 3.01/3.66 percent versus 3.7/4.7 two years
ago, and C02 levels were well in the acceptable range, of course.
All in all the car is still very clean. Interestingly, my test two
years ago was done before my recent cylinder head refresh, and it was
drinking a quart of oil every 100-200 miles. Now it's a quart every
4-5000 near as I can tell. Substantially less oil consumption -
higher HC. Go figure!
I had the MAP sensor set 1/16 turn CCW (rich) from the OEM position
that I marked years ago. Since the car was reluctant to start with
the MAP sensor there and the idle pot three notches from full rich, I
reset the idle pot to one notch from full rich. It started better,
but not perfectly, and I reset it to two notches from full rich before
the test, but it was still probably a bit lean.
So it looks like reindexing the cams (along with the required retuning
of the MAP sensor and ECU idle pot) will not increase emissions to
unacceptable levels if you still have to have your car tested. In my
case, unless CA changes the current 30 year exemption rule for
emission testing, this was my last test. As of 1/1/03 all '74 cars
are exempt, so mine will be exempt on 1/1/03, which is a month before
my registration renewal is due, so I should be off the hook.
Duke
[This is message #10463 by user doctorduke on Yahoo! Group Cosworth Vegas: http://groups.yahoo.com/group/cosworthvegas ]