J R C

Went through most of the archives and didn't find specifics ... I'll be up for IL emissions test next month and want to keep my regular plates so I'd like to know what "real life" '72 to '74 vettes emission tests results have been among those who still need to have their cars checked. Mine is a '74 but the same levels apply to the '72 to '74 model years in my state. According to IL the readings can't exceed 800 ppm (parts per million) HC, a CO % higher than 8.0% and a combined CO & CO2 of 6.0% ... according to IL EPA these are at least 20% higher than the federal limits but I'm curious what a well-tuned, none modified '72 to '74 will typically run. According to my mechanic I've got good compression, don't burn any oil and the car runs out pretty good. I've got the SB L48 with a stick but the "test" doesn't differentiate between SB and BB ... I have seen that some cars have passed with "flying colors" in the archives so if you still have the print out from your inspection station I'd like to see what the report said ... Thanks!

princeRed72

I have a 72 SB w/4spd and pretty stock. I asked this same question awhile ago but found out there really were no "standards" for 72. I even have a SEARS emissions tester I picked up at a flea market, it was in with some other stuff. The readings on my car are well within the specs in the instructions, less than 5% I think. This is witht he timing set as per LARS' instructions

I want to be able to check it on a friend's car, 69 350/350 hp 4spd who just had the car tuned and carb set.

Be interested in wha tyou find out :auto:

J R C

In IL they test all of the way back to a '68 ! (only '67 & earlier are exempt) you also can't get an antique plate here but I'd rather not as I plan to use it for more than shows & events, etc. Listed below are IL standards for '68 to '71 which would cover your friends '69 (if it was registrered in IL):

1968 – 1971
HC 900 ppm
CO 9.0%
CO+CO2 6.0%

Also, the 5% you mention was that the CO reading? if so that's pretty good!

71'AirStrike

for whats its worth :) Arizona, 1971 BB
every year this test is done.

HC=hydrocarbons in PPM
co= carbon Monoxide in%

Max number / My result

Loaded reading
HC 450 / 88
CO 3.75 / 0.57

Idle reading
HC 450 / 425 (eek little rich!)
CO 5.00 / 2.19

chad




[Modified by 71'AirStrike, 8:58 AM 4/15/2004]

zwede

8% CO and 800 ppm HC is very lenient. Easily passed unless something is seriously wrong with the motor. The combined CO+CO2 is only a test for exhaust leaks.

Decently tuned you're looking at 2-3% CO, 300-500 ppm HC at idle.

J R C

Thanks zwede! IL also offers a "voluntary" pre-test for $20 that I might take them up on to see where I'm at ... I had a bad experiance with a '74 MGB a few years back that wouldn't pass even after several attempts at tweaking it ... ended up selling it to a guy in FL (it was in '97 too "new" to get antique plates at the time). It appears if I keep it in a good state of tune that I should be OK ... will make sure its fully warmed up, etc., etc. before I get it tested. This is an idle only test (no rollers) so will see ...

rponfick

This is an interesting discussion since I just bought a 73 big block and noticed a "failed" report in the papers in the car. The Colorado limits for cars older than 1982 are 1000 HC and 4.5 CO. The car exceeded the CO level at idle (5.01) and at 2500 RPM (6.10). I'm hoping I can lean down the carb enough to get the levels under maximum. The car has collector plates on it, but you have to get it retested when you purchase. Once you have collector plates you don't have to test it again as long as you own the car.

I'm sure Lars will be able to perform his magic on the carb. :cheers:

thevetterisbetter

I have to go this month. I have a 74 383 4 speed with the stock carb. Running poorly right now, but not too worried. I will let you know how I do after I go.

J R C

Well ... decided to go for the "voluntary" one ... the mgr at the Lincolnshire, IL testing station was great in that he allowed a "free" pre-condition test (must have a soft spot for 'vettes!) anyway the car failed badly! Results were: 1954 for HC, 0% for CO and 5.0% for CO2 ... test said that I must have a leaking exhaust as the exhaust had "excessive dilution" ... the car has always smelled a bit of exhaust but I've always thought that as somewhat normal ... will be checking out local shops that can verify what leaks I have (mainifold or otherwise ... don't have a lift so will leave this for the experts)

zwede

Ouch! 1954 HC is massive. Basically you have raw fuel coming out the exhaust. Is it missing?

Edit: Years ago I built up an engine for an old Camaro. No emissions to worry about so it got a cam, non-emission holley carb etc. I took it to a dyno that also had a 4 gas analyzer on it. It blew 3% CO, 500 ppm HC at idle and much less at speed.


[Modified by zwede, 4:19 PM 4/17/2004]

J R C

Zwede ... enjoyed the rest the great weekend here in Chicago before I checked back on the forum. This is the weird part ... the car appears to run very well ... without trying very hard it chirps second gear and doesn't backfire, burble or make any other strange noises. According to the "reject" sheet I have a number of things that I should be checking (vacuum lines, exhaust, etc.) so plan to do that. My mileage also although not great (about 12 or 13mpg) leads me to believe that it's not raw fuel (wouldn't you smell that ... unburned fuel?) in any case according to the emission guy I can continue to have it retested as many times as I like through this August (although I thought IL EPA limited it to three trys) ... I'm not bringing it back to be tested until I have a shop verify that everything is working as it should. I did notice that I don't have an air pump on it but based on your comment above the car properly tuned shouldn't need it ?

J R C

Here's an update ...

Thought I would provide an update because the re-test results were so good ... although I thought the car was running great as-is it turns out my carb settings MUST have been real rich. My local mech' put it on his scope today and the high HC's were due to the carb settings, no leaks in the exhaust so I'm good to go for another two years, yee hah! Now I get to keep my regular plates and move on to the cosmetic stuff (new bumpers and a re-paint, etc.) ... I REALLY did not want to have to go with the antique plates even though many folks get by this way in IL ... I guess it was just the principle of the thing that it should pass in proper tune. Anyway ... the new readings are: HC 64ppm (yes, a 64 not 640); CO is 1.4% and on the print out it appears that CO2 is at 12.4% but they indicate an "N/A" for a requirement for CO2 so that one didn't matter. After driving it home today the only thing I did notice that the "cold" idle was a bit higher but otherwise the driveability feels the same and the exhaust smell is barely there now. Would be curious if my mpg goes up so we'll see!
:chevy

zwede

See, emissions testing isn't all bad. :cool: