Need to pass CA smog. Mixture and duty cycle?
 

Hello all,

well, time to visit the good ol smog shop so I can renew the registration on my car.

Here's the scenario;

Stock exhaust (now)
Cat gutted
O2 sensor disconnected
35 degrees total advance at 6K
50% duty cycle current mixture


I believe I need to get the CO down to .5 from 3.5 (approx) to pass. Does anyone know if there is a duty cycle number which correllates to that? Any other advice?

Thanks!

Brad, I just smog’d my car a few weeks ago.

You’ll need to lean the fuel mixture so the CO is back to spec (.4-.8%), retard idle advance back down to 5 BTDC, and just for good measure (in case they look) connect the O2 sensor back up. It should pass beautifully like that.

Just make sure you get her all tuned back up for BBRIII, and try to have that awesome exhaust back on too.

Right on! Thanks Ryan. I don't have a way to check the CO, but I am hoping that if I lean her out to where she starts to run bad, I can richen just a bit and get by. Think that will work?

I'm gonna try to get the exhaust back on, time is short, though. Guess I better get my priorities straight, huh :)

I have a Gastester if you need to borrow one. I can give it to you at BBRIII.

As far as doing it by feel, you could probably get away with it. After you set the timing, lean (counter clockwise) it out until it will barely idle, readjust the idle adjustment, and then richen (clockwise) it back up just ‘til it runs, but not great. If it stalls on you right after start-up, or while idling, richen her up a little more. Make sure you get a pretest if you try this so you know it’ll pass before the real test.