Alright about a month ago, I came on here and asked for some help on how to pass emmisions in illinois by adjusting my carb. I was basically told to just create some vacuum leaks. So what I did is opened up a huge vacuum leak on the side of the carb, and pulled off the vacuum advance which I guess was a huge mistake, could anyone explain to me why this was a huge mistake. I failed the test really bad, I also had two cats on my car also. Well since then I found out that one of my cylinders werent firing because I got new headers, and all the paint was burned off them except for one tube then we fixed that and its fine, so one clyinder wasnt burning fuel. Now if anyone could please please please help me with a step by step process of what I could do with my car to make it pass, it would be really highly appreciated. I dont want to lose the rights to drive my car on the street! Thanks for any help

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1991 teal camaro RS rebuilt 96 350 marine motor, comp cam, accel ignition,8mm accel plugs and wires, hedman headers and y-pipe, and rear end with 4.10 gears. Stock 700r4, best 1/4 time 14.6

 

It would be helpful to know what type of test is being performed (idle/cruise sniffer or dyno), and what your readings and standards are. But a misfiring cylinder will fail you without fail. You should be in good shape now.

The reason the vacuum advance should be hooked up is that at cruise, the additional advance helps the cylinders burn more of the fuel, meaning the throttle doesn't have to be open as much to feed it. Without the added advance, vacuum will be lower, which opens the power valve more, making the mixture richer, meaning more fuel is unburnt in the shorter time between ignition and BDC, etc., etc., etc. A big snowball affect.

Set the idle mixture slightly leaner than optimum, open up a vacuum leak (other than the vacuum advance) if you like, give it another shot.

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82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R4. 2.93 limited slip. 2-1/2" cat-back, ZZ4 intake, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (ported World 305 heads, Crane PowerMax cam, Hooker 2055 headers, 3" Catco cat & 3" catback, restalled TC, Spohn SFCs).
57 Bel Air, my 1st car. '66 396, 9.7 CR forged TRWs, Weiand Action+, Holley 750VS w/4150 conversion, GK 270 cam, Magnum rockers, Jacobs Omnipack, 1-3/4" Hedders & 3" Warlocks, TH400 w/TCI Sat Night Special conv & Trans-Scat shift kit, MegaShifter, 3.08 8.2" 10-bolt w/Powertrax, AMSOIL syn lubes bumper-to-bumper. Idles smooth @ 600 RPM in D. Best 15.02/95.06 @ 5800' Bandimere (corrected 13.93/102.4 @ sea level).