I just failed my emission test today. Is there any tricks I can do to try and get it to the standard. Here are the results
_________2671 RPM________692 RPM
________ HC______CO______HC________CO
standard 700_____5_______700_______5
reading 279_____6.07____944_______7.87
_________Pass____Fail____fail______fail

I put some of that emission pass stuff in the gas to see if that will help. Any other tips are much appreciated.
thanks in advance

ps Its a 70 350 4bbl edelbrock 650 carb.

Looks like your a little rich at idle. I would do the following:
1. be sure your air filter is clean because even if the carb is set up right, if there's not enough fresh air the car will run rich.
2. Check your idle mixture, could be rich.
3. be sure the car is warmed up prior to the sniffer.
4. Is the engine oil clean?
5. Raising the idle speed may help a little.
6. Hot Rod magazine did an article a couple years back you may be able to find it on their web site.
Good luck
-Bill
'66 SS 396 in pieces

I agree with the above and would add that you should check your spark timing at idle. You might retard it a bit for the purpose of the test. This will put a bit more heat into to the exhaust gas and help encourage more oxidation of the HC to take place in the pipes.

Thanks for the info, just a quick ?, I'm not too good at timing stuff, do you turn Clockwise or counterclockwise to retard it?

Originally posted by JWagner:
I agree with the above and would add that you should check your spark timing at idle. You might retard it a bit for the purpose of the test. This will put a bit more heat into to the exhaust gas and help encourage more oxidation of the HC to take place in the pipes. Providing they dont check the timing for testing purposes,retarding the initial is correct,& will give the fuel more time to burn.
If its a Chevy,move the distributor body clockwise to retard,& raise idle speed as needed. graemlins/beers.gif

Is the oil new?
plugs new? Reason I ask is the HC is really high. HC is unburned fuel like a miss fire. A missfiring cylider will produce 1200-1500 ppm of HC as the rpm runs up the heat in the exhaust helps burn it. The co looks like it needs an oil change. Remember the limits that are set are typically 3 times higher than where the cars normall outputs should be! a lean missfire(vac leak) will cause hi HC treadings as well. Good luck
Milan

I second the fact that you should change the oil. Oil has the tendency to capture any unburned gasses causing them to be released later as the oil gets more "dirty". I always change the oil prior to going for my emissions test. Another good helpful hint I have found to help out a little is putting a can of dry gas into the gas tank. This helps remove any moisture in the gas which can effect your emissions readings. Also, if you havent, do a complete tune up. If not a complete tune up, at least the fuel filter, air filter, breathers, pcv valve, spark plugs, and cap / rotor. All of these will help for a better burn in your combustion chamber.

thanks for the help, but still no luck.

I went back with the timing adjusted and some dry gas and passed everything but the CO at idle. So here is where the sob story starts.

I changed all that stuff, cap and rotor, plugs, wires, and oil and filter, and I'm thinking there is no way I'm not going to pass. And I go back and its still to high on the CO at idle. At that test I had forgot to check the timing, so it was really far retarded, so I moved it back to about 6 btdc, and went back, thinking that would do the trick, but this time it was in the 3000's HC on both, and passed both CO.

I'm a little frustrated.
My jets say 39X and the rods are brown with a gold tip looking with the number 7547 on them do I need to put different jets in? Its a edelbrock 750cfm. One thing too, is that my idle seems too high like in 1200 or so before it will idle in gear at all, could that be related? If I turn it down below like 900 or so it just kills when i put it in gear.
thanks for any help

Originally posted by popbirch:
thanks for the help, but still no luck.

I'm a little frustrated....
My jets say 39X and the rods are brown with a gold tip looking with the number 7547 on them do I need to put different jets in? Its a edelbrock 750cfm. One thing too, is that my idle seems too high like in 1200 or so before it will idle in gear at all, could that be related? If I turn it down below like 900 or so it just kills when i put it in gear.
thanks for any help popbirch,

Couple of things come to mind. I see that you changed the oil and filter, but did you change the air filter?

(I'm a little confused on what size Edelbrock you have. At the beginning you say it's a 650 and at the bottom you say 750) Regardless, you need to check two things closely:

A)Verify that the choke opens all the way when the car is fully warmed up.

B)I would double check the float settings. If you are running rich there is no way you'll pass an emissions test.

I'd check the float before I start changing jets IF the carb still has the original jets and rods.

Mike

ps It's possible you retarded the timing too much. What do you have it set at? Do you know what it was set at when you failed the first test?
Once you get your timing back to where it should be, your idling in gear problems will go away.

Hey thanks again but still no luck, I adjusted to floats down so they not so much gas gets in, and I have the timing set at about 4-6 btdc with the vacuum advance connected. I still fail on HC like about 2600 at idle 3000 at speed. Should I retard more? like 12-16 maybe? I haven't changed the jets but the previous owner might have. If I take out the PVC for the test will that bring it down a little. As for the previous failures I don't know what the timing was set at because I didn't have a timing light, but for this last test me and my uncle set it correctly. if you retard too much do the CO readings start going up? Cause my car passed once before and I had just twisted the distr about 30 degrees and then went in and did the test, but when I tried that this time I failed on CO. Ok thanks for any more ideas

Originally posted by popbirch:
Hey thanks again but still no luck, I adjusted to floats down so they not so much gas gets in, Did you set it to Edelbrocks' specification?

and I have the timing set at about 4-6 btdc with the vacuum advance connected . Should I retard more? like 12-16 maybe? Retarding it MORE would be like 0-2 degrees btdc. I would set it with the vacuum advance disconnected and go for maybe 4 degrees btdc. Are you using ported or manifold vacuum?

If I take out the PVC for the test will that bring it down a little. If you remove the PCV valve you will fail the visual part of the inspection. Removing it will not make your co go down more.

if you retard too much do the CO readings start going up? Not directly.

!!!Since high CO is generally a fuel problem, it's very important that you ensure that you don't have any obstructions in your air cleaner assembly, the air cleaner element is clean, your choke opens fully, your floats aren't fuel saturated and are properly adjusted, and your air/fuel mix at idle is set correctly!!!Mike