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Time for the magic smog check...

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by MaxCrack, Dec 11, 2001.

  1. MaxCrack

    MaxCrack 1/2 ton status

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    I took my truck to a local guy to see if I could pass smog so I can register it again so I can get my custom plates (RNM OVER). It's not even close to passing. I filled it up with 91 and put a couple bottles of Isopropynol (rubbing alcohol) and since I can't go over 25 without the whole damn thing shaking like it's going to explode (I hate that Dana 70 front end) I revved it up good for a while to warm it up.

    Well, it's not even close. At idle I have around 750 ppm of one thing which I am supposed to be down around 650. PITA. So I called my buddy in San Jose. He said yeah, bring it down, I'll see what I can do. It's an hour drive each way at 20-25 mph plus a trip to the DMV for a moving permit, but if he can pass it, it's worth it.

    A computer once beat me at chess, but it was no match for me at kick boxing.
    <a target="_blank" href=http://photos.yahoo.com/dana60manual>http://photos.yahoo.com/dana60manual</a>
     
  2. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Try setting your idle higher. My truck has a reasonably mild cam but the 'overlap' at a low idle is enough to fail me on the idle test every time. I adjusted my idle to 950 and passed with flying colors. After passing I reset my idle to 700...

    Rene

    <font color=green>Dyslexics of the world...UNTIE!</font color=green>
    <a target="_blank" href=http://coloradok5.com/gallery/project_T2> tRusty pics...</a>
     
  3. White Knight

    White Knight 1/2 ton status

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    I've got a 77 GMC P/U that would never pass, then one year I put in 5 gal's on a empty tank of 102 aviation fuel, got it real hot and it flew through the test in Texas, so for the next 5 years thats what I did each time. Might try it! no harm in trying.

    White Knight
     
  4. rampage

    rampage 1/2 ton status

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    Which reading is over the limit? Is it the hydrocarbon or cabondioxide? That will help to tell where the problem lies.
    I have a 77 that wouldn't pass and it had a dead cylinder due to a hydraulic lifter along with a blown head gasket. Once those were fixed it passed with almost unmeasurable readings.

    <P ID="edit"><FONT class="small">Edited by rampage on 12/12/01 12:25 PM.</FONT></P>
     
  5. MaxCrack

    MaxCrack 1/2 ton status

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    I'm pretty sure it was the hydrocarbons that were up around 750.

    A computer once beat me at chess, but it was no match for me at kick boxing.
    <a target="_blank" href=http://photos.yahoo.com/dana60manual>http://photos.yahoo.com/dana60manual</a>
     
  6. Executioner

    Executioner 1/2 ton status

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    Temp. Ft. Walton Beach Fl. home=Tucson, Az.
    Your HC's should be lower than 600 ppm .
    An engine in good tune should be in the 1-200 HC's ppm range.
    Good luck
     
  7. EZdoesit

    EZdoesit Registered Member

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    well, 750 ppm isn't too bad if you only need to get it under 600, do you have a working cat. convertor on it? I don't know if cats are required for a truck as old as yours in CA or not, what about an air pump?
    One other thing you could try is retarding your timing way back, I've seen a truck that passed that way, even though it would barely idle.
    Check to make sure all your plugs are clean too, I saw a car that failed emissions miserably bad because one plug had a piece of carbon on the electrode, cleaned the plug off and the HC dropped to like 150 ppm.
     
  8. DzrtRat67

    DzrtRat67 Registered Member

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    Been thru similar nightmares down here in AZ. (do a search for me and you'll come across several posts with lotsa helpful info from other ck5ers)
    Nowadays, I've got it down...here's what I do, followed by my readings...all for a stock 77 with a 350.
    1. Put at least one cat on, whether they're required or not....think ahead and do it w/o welding (although I had mine welded)...that way you can take it off, replace with pipe and save it for next year.
    2. Lean down your carb a bit lower than you would want to drive with, and turn up idle to compensate. Careful! too lean can cause other emissions nightmares!
    3. Run tank down to about 1/4...then put in a half gallon - 1 gallon of DENATURED alcohol...yes..the stuff at Wal-Mart is fine.
    4. For what it's worth...I also drilled some holes in the top of the pipe behind the muffler, then took a small punch and bent half the hole in...the front half...kinda like a cheese grater shape...the theory being that the exhaust going past the altered holes, would draw in a bit of fresh air, lowering the PPM...Now, in all fairness, I doubt this did much, other than to help bolster my feelings of "I'll show those bastards" kinda cleverness... you may wish to skip step #4. (although, I did it to both my Blazer and -eeekkk-- my Bronco II, and both passed with flying colors!)
    5. Make sure truck is good and warm when you get to emissions...
    These simple steps have worked wonders for me... here's my last test results:
    allowable / my results
    Hydrocarbons ppm at Idle = 350 max / 133 mine
    Hydrocarbons ppm under load = 350 max / 75 mine
    Carbon monoxide % idle = 4.00 max / 0.00 mine (no, it's not a typo!)
    Carbon Monoxide % loaded = 3.00 max / 0.00 mine (again, no [censored])
    Despite the hole drilling, I'm pretty certain that the combo of factory compliant timing, lean carb, catalytic, and mostly the denatured alcohol are what actually did the trick.
    Hope this helps...if you can post more details about your timing, how many turns of carb screws, etc....it may help others help you..
    Good Luck!
    Rat
     
  9. sinchphoto

    sinchphoto 1/2 ton status

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    theres shops there that will MAKE it pass.
     

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