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Home Smog PreTest?

Discussion in 'Technical Q&A' started by donaldh2o, Mar 30, 2004.

  1. donaldh2o

    donaldh2o Karting

    Nov 10, 2003
    143
    Irvine CA
    Full Name:
    Don
    Is there any way to tell whether the carbed 308 is running rich or lean without an elaborate CO tester?

    Mine failed the California smog test months ago. It was running too rich. Too much CO. Now I've finally finished tuning it up and need to pre-test it before I take it for an actual smog test.

    I've already turned all eigtht carburetor mixture screws all the way in and then backed them off 3 turns (and I assume the manual means 360 degree turns).

    The carburetors are all balanced at about 3.75 kg/h using the SK-1 synchrometer and the idle is set at abouit 900 rpm. Timing is set about 8' or 9' before tdc.

    Is there a clever home method of pretesting the CO level?

    Like maybe holding a peeled apple or potato up to the exhaust and if it turns a certain color its rich and another color if its lean?
     
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  3. Steve King

    Steve King F1 Rookie

    Feb 15, 2001
    4,365
    NY
    Well Don I'm impressed if you can get you car to run on 3 turns out on the carbs. The air bal. seems right but with 3 turns you should be running to lean. I need to crank my out to around 6-7 turns to get to run great up at top end. It is rich at idle but goes like hell when you light it up. I would suggest you get a colortune kit and do each cyl. at a time Then tweek it back a hair to lean it up for the smog test. I also run my timing at 7 deg.
     
  4. PeterS

    PeterS Three Time F1 World Champ
    Silver Subscribed

    Jan 24, 2003
    39,255
    95370
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    PeterS
    "Like maybe holding a peeled apple or potato up to the exhaust and if it turns a certain color its rich and another color if its lean?".........

    ..I tried this with my EX and it did not work to well. When she turned blue, the engine was still running rich.
     
  5. donaldh2o

    donaldh2o Karting

    Nov 10, 2003
    143
    Irvine CA
    Full Name:
    Don
    So Steve, you've used this Colortune kit on a 308?

    I saw this thing while net surfing for a new SK-1 synchrometer. It looked interesting and it seems to be popular with Volkswagen bug tuners. My first thoughts is that it would be too recessed in the 308 valve cover to be seen clearly.

    But if it works on a 308, that would make it a valuable tuning tool.
     
  6. zan

    zan Formula Junior

    Nov 15, 2002
    537
    Boston
    Full Name:
    Mark M
    Lock your wife in the garage with the engine running, if she's still breathing in half an hour, you CO levels are OK.
     
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  8. wax

    wax Four Time F1 World Champ
    Advising Moderator

    Jul 20, 2003
    45,027
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    Dirty Harry
    Is the car OK, though?
     
  9. Steve Magnusson

    Steve Magnusson F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    19,706
    Texas
    Full Name:
    Steve Magnusson
    Don -- What's the CO at-tailpipe test target that you're trying to meet?
     
  10. nautique

    nautique Rookie

    Nov 1, 2003
    20
    Los angelas, CA
    Full Name:
    Craig Tempelton
    Don,

    Unfortunately in California, you will probably get put on the dyno test machine. This does not test your car at idle, it test while running. A colortune is great for setting your idle mixture but will not help you pass the ca smog test.

    I go through this every 2 years. You need to find a shop that will pre-test your car without sending the data to the DMV. If your car is running good it probably will not pass. You will have to test and then re-jet the carbs. I had to jet at 50 idle circuit and 120 mains (car ran bad but passed). I probably could have run 52 and 122 but did not have any.

    Good luck, it always takes me about 4 or 5 pre-test to pass
     
  11. Wayne 962

    Wayne 962 Formula Junior
    Rossa Subscribed

    Nov 27, 2003
    442
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