CA ASM emission test results w/reindexed cams

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CA ASM emission test results w/reindexed cams

Postby h-bot » Fri Jan 31, 2003 5:31 am

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 ]
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CA ASM emission test results w/reindexed cams

Postby h-bot » Fri Jan 31, 2003 6:46 am

From: doctorduke_REMOVE_476167_THIS_@yahoo.com

--- In <a href="/group/cosworthvegas/post?protectID=219233066105193209050199029077192253163098100009128121188190230091025019053061151110147">cosworthvegas@yahoogroups.com</a>, "Mark A. Rock <<a href="/group/cosworthvegas/post?protectID=029166091163127190025067203043129208071">markrock@c...</a>>"
<<a href="/group/cosworthvegas/post?protectID=029166091163127190025067203043129208071">markrock@c...</a>> wrote:
> Duke:
>
> Congratulations! Doesn't it give you a good feeling when your
> engineering work produces the results you expected/predicted?
>
> These engines may be old, but they still have some secrets to
> surrender, and some horsepower and torque to unleash.
>
> So what's your next project?
>
> Mark

I knew the NOx would increase with less overlap. I just didn't have a
good intuitive feel for how much, but being as how I was only about 20
percent of the limit with the OEM indexing it could have at least
quadruped, and I still would have passed.

I believe I have pretty much optimized the torque curve. Another
project I've thought about is opening up the air cleaner inlet and
building a cold air induction system to the fenderwell using the
screen and hose from a 140 Vega (keep that OEM look). It would
require a 2.5" hole in the inner fender just forward of the air
cleaner inlet. This would place the screen between the inner fender
and the plastic fender liner where ambient air is available, but the
opening is well protected from splash.

The only other improvement I see is to raise the CR, but being as how
my short block is in good shape, I'm not interested in tearing it
apart.

Right now the car is running so good I'm just going to enjoy it for a
few years before I do anything major.

Duke




[This is message #10471 by user doctorduke on Yahoo! Group Cosworth Vegas: http://groups.yahoo.com/group/cosworthvegas ]
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CA ASM emission test results w/reindexed cams

Postby h-bot » Fri Jan 31, 2003 7:32 am

From: markrock_REMOVE_932339_THIS_@yahoo.com

Duke:

I'm interested in a cold air package as well. The "need" for this
will diminish as the re-indexed sprockets reduce the underhood
temperatures, but it will still provide a measurable benefit. Some
time ago I saw something in Hot Rod indicating how much HP decreases
with an increase in the temperature of the air coming into the
engine. I don't remember the numbers, but they were significant
enough to start me thinking again on that topic.

My thought had been to move to the 76 battery tray and a small
battery, and duct from a long, narrow slot "outboard" of the battery,
but there just isn't enough clearance.

I'd welcome any drawings and measurements. As the engine compartment
in Crispy Critter is bare, and the fenders are still off, now would
be an easy time to make this modification. I'll have to talk to Tom
Lippert and see if he has the hose and screen you mention. I'm not
familiar with it. If anybody else has one, please e-mail me.

As for the increase in CR, that could have been an easy thing when
you last had your head off, depending. Merely switching to new
valves will up the CR since the new valves have "flat" heads, unlike
th stock valves which have a depression in them. This will give at
least a half point of compression, and more if the stock valves have
been cut once and thus recessed toward the seats. But if you have
already replaced your valves, then you are already there.

Mark




[This is message #10473 by user markrock on Yahoo! Group Cosworth Vegas: http://groups.yahoo.com/group/cosworthvegas ]
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CA ASM emission test results w/reindexed cams

Postby h-bot » Fri Jan 31, 2003 8:04 am

From: doctorduke_REMOVE_141770_THIS_@yahoo.com



Power across the range increases/decreases for every 10 degree
decrease/increase in inlet air temperature.

I still have the OEM valves. If one is going to increase CR it should
be raised up to the 10-10.5:1 range to get a signficant change, and
this will require new pistons and the use of premium unleaded fuel.
Increasing the CR two points from OEM will improve power across the
rev range on the order of seven percent.

Duke




[This is message #10474 by user doctorduke on Yahoo! Group Cosworth Vegas: http://groups.yahoo.com/group/cosworthvegas ]
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CA ASM emission test results w/reindexed cams

Postby h-bot » Fri Jan 31, 2003 1:23 pm

From: markrock_REMOVE_751754_THIS_@yahoo.com

Duke:

Congratulations! Doesn't it give you a good feeling when your
engineering work produces the results you expected/predicted?

These engines may be old, but they still have some secrets to
surrender, and some horsepower and torque to unleash.

So what's your next project?

Mark






[This is message #10468 by user markrock on Yahoo! Group Cosworth Vegas: http://groups.yahoo.com/group/cosworthvegas ]
h-bot
 
Posts: 53214
Joined: Fri Dec 15, 2006 8:30 am
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