Author Topic: Another Aircare Question (Read 1406 times)

mike · « **on:** September 01, 2007, 09:02:02 PM »

I guess it's aircare season... getting our cars ready for the next season..

I just took mine through today and i didn't pass due to high CO at idle. Can someone (Bruce?) help me out and point me in the right direction?

Idle HC 939 ppm MAX 1052 ppm
Idle CO 7.78 % MAX 5.54 %

I have my timing set 12@idle(~800rpm) and 28@3500rpm (Mallory)

Should i just just my idle to say 1100 rpm to help with the results? Would adjusting the timing affect the CO at all?

This is a 2110cc, 86B with 45 Dellortos /w cb update kit, 38mm vents 65 idles, 165 Mains, 180 airs.

My VIN is 1928242 if you want to look at my Aircare results.

Any help would be greatly appreciated!

Michael

Hansk · « **Reply #1 on:** September 02, 2007, 01:17:43 AM »

I'd guess that thing has a rough idle. If so , you've got to play with balance and mixture screws to get it silky smooth. Hopefuly that would bring down both hc's and co's. If not , you may have other problems. I didn't look up your #'s so I don't know what your driving results were.

Bruce · « **Reply #2 on:** September 02, 2007, 02:21:15 AM »

Driving numbers are perfect. Idle CO is rich, HC is also rich.

Increase your idle speed to 1000-1050. Watch the timing at that RPM. If that dist allows you to pick your idle timing, set it to 8-10

mike · « **Reply #3 on:** September 04, 2007, 05:58:13 PM »

Thanks for the replies guys!

I will make the changes to the dist to increase my timing range tonight to see if that'll help.. As for the mixture screws, I had them set the same way as you described; however i had then turned in an additional 1/2 turn for safe measure. I'll re tune it to have it dead on.

Bruce, would you be able to explain how reducing the timing will help in decreasing CO readings? My thinking is that more advance would be better as the burning of fuel would start earlier and complete sooner in the chamber rather then in the exhaust tract. Am i waaay off?

Thanks!

Bruce · « **Reply #4 on:** September 04, 2007, 07:37:33 PM »

Timing has little effect on CO. Raising your idle speed will have a larger effect at lowering CO. The timing adjustments I suggested are to bring your HC down. At 949 it is really high. A clean engine will blow less than 200.

I just re-read your initial post. Have you ever passed with the CB update kit? Are those the jets that came with the kit?

mike · « **Reply #5 on:** September 09, 2007, 11:30:15 PM »

Hey Bruce,

I made the changes recommended by you and to make a long story short; she passed with some very low numbers. I managed to pass her last year with the CB update kit so I'm not too sure what happened this year.

During the timing change I also made a spring change in the distributor to make the advance curve faster to get rid of an off idle bog. I don't think it would of affected any of the readings but my off idle bog is not as bad anymore.

Thanks for all your help!

Michael

Bruce · « **Reply #6 on:** September 10, 2007, 12:39:33 AM »

The numbers now look very clean. You should write down all the variables you can think of on your report.
Timing
Idle speed
Ambient temp
Oil temp
gas used
etc.
Then next year you will be able to set those variables and pass again.

mike · « **Reply #7 on:** September 10, 2007, 10:03:12 PM »

Thanks Bruce, I've got all those variables noted.. However I don't think i remember what the weather temperature was that day.