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Emissions SUCKS !!! (updated)

Discussion in 'The Garage' started by 4xcrazy, May 22, 2006.

  1. 4xcrazy

    4xcrazy 3/4 ton status

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    Ran this P.O.S. through twice, with TWO different carbs and timing adjustments, and came back with very similar results,,,kinda wondering if the small tires with the 4.10's in the rear end are causing the motor to rev too high and pump out more emissions than allowable,,,,


    I really hate this crap..:mad:

    If ya wanna know,,,,,'81 C-20 2wd, with a semi-fresh rebuilt 350/th350, RV cam, headers, cats, true dual exhaust setup, and little tires, "ASSUMING" 4.10's by the way the motor rev's up real quick from take offs,,not a highway friendly truck...

    Hydrocarbons @ 6.21 allowed 4.40...failed

    Carbon Monoxide @ 115.38 allowed 48.00....failed BIG TIME

    (NOX) @ 3.20 allowed 7.00,,,this is fine

    just about ready to yank the motor and part it out like the original plan was to do with it.:mad:


    OH, BTW, this same motor was in my Nova when it wasn't wrecks and still driveable, and pass emissions just fine,,,so i am kinda lost.
     
    Last edited: May 23, 2006
  2. 1-ton

    1-ton 1/2 ton status Premium Member

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    Do you have a smog pump (A.I.R. injection)?
     
  3. 4xcrazy

    4xcrazy 3/4 ton status

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    no, didn't have one on there.
     
  4. 1-ton

    1-ton 1/2 ton status Premium Member

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    I am not sure of you are supposed to have a smog pump. CATs perform the same function as a smog pump does. They burn up unburned gas. If this where an original 1981 Arizona Federal emissions truck, then it would be unlikely that your truck ever had CATs originaly. It would have been a leaded burning engine with an EGR and a smog pump like my 1985 K30, which is an original Nevada Federal emissions truck. The only way your 1981 truck would have been an unleaded burning truck with CATs is if it where from the Republic of communist California. The problem could be a bad carburetor, unless at least one of the carbs you are using is new.
     
  5. 4xcrazy

    4xcrazy 3/4 ton status

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    That is what is throwing me off, i tried two different carbs, and they both came back with very similar readings, it would seem they should be somewhat different, even if they were both bad, it seems they should be alittle more off than they are.

    I have a Edlebrock carb and manifold on another motor i am seriously thinkin about buying a re-jet kit and run it as lean as possible, it doesn't have the EGR valve though, but the NOX was already WAY lower than the standard, so i don't think this will be a problem as it wasn't even hooked up when it went through this second time.

    I just don't know though...:confused:
     
  6. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Are these idle numbers or driving numbers on a loaded dyno?

    Rene
     
  7. 4xcrazy

    4xcrazy 3/4 ton status

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    sorry bout that, driving loaded on the dyno

    new style of test too, where they imitate actual driving with different throttle positions,,not like the older one where they'd hold it one rpm
     
  8. K10ANDYKHAMNIC

    K10ANDYKHAMNIC 1/2 ton status

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    its probly the true dual cats not heating up enough .
     
  9. 1-ton

    1-ton 1/2 ton status Premium Member

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    That is a possabilty, because one CAT only recieving the exhaust gasses of one bank of cylinders may not be hot enough.
     
  10. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    They've always done the dyno test like that here...:crazy: and the diesel test runs almost three minutes long with a WOT "hillclimb" from 16 mph to almost 60 mph.

    Anyways, if you lean it out too much the NoX will go through the roof. The truck was completely warmed up both times? If the choke is even partially engaged you'd get numbers just like that...maybe the choke is sticking a little?

    Rene
     
  11. k20

    k20 3/4 ton status

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    how old are the plugs, wires, cap, rotor?
     
  12. 1-ton

    1-ton 1/2 ton status Premium Member

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    I wonder if they are going to start dyno tests here in Nevada? That would be an expensive peice of equipment for the smog inspection stations, which would be passed onto the consumer...of course.
     
  13. K10ANDYKHAMNIC

    K10ANDYKHAMNIC 1/2 ton status

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    get hotter plugs .... maybe
     
  14. FWP

    FWP CRS

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    Ditto.
     
  15. mosesburb

    mosesburb For Rent Premium Member GMOTM Winner

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    Why not just re-jet the carb you have instead of swapping manifolds and carbs??
     
  16. 4xcrazy

    4xcrazy 3/4 ton status

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    Was going to try to re-jet the Quadracrap, but cannot get the metering rods and parts to do it very easily/quickly, the plugs/cap and rotor are all good,,,

    i was chatting with a guy down at Carquest, and got to askin me about the "setup" so i told him, and we came to the conclusion, i may have the timing WAY too far advanced for this engine and cam setup, he was saying that alot of cams are already advanced by themselves about 4degrees or so, and then i went and advanced the timing some more from stock to try to counteract the hotter cam things that may happen.

    So tomorrow i am going to throw the vacuum gauge on it, reset the timing alittle less than stock setting, and adjust the carb up from there all while watching the vacuum gauge:crazy:

    As mentioned before, this is just too weird that two different carbs with same type of readings, but both run awsome driving down the road,,,,DAMN these Chevy engines LOOOOOOOVE GAS !:eek1: :D

    will update at a later date, thanks for the replies...
     
  17. 88-383

    88-383 1/2 ton status

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    My thoughts exactly, try and take some timing out.

    KM
     
  18. 1-ton

    1-ton 1/2 ton status Premium Member

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    I can pretty much garauntee you that any factory GM Q-jet you are running is a wasted pile of crap. The fuel well plugs are probably dumping raw fuel into the intake manifold, regaurdless of how much epoxy or ceramic you may have on them. My guess is you have two worn out piece of junk carbs that are dumping raw fuel into the engine, which is why you are not passing smog. There is a saying: "you get what you pay for". if you have two used up carburetors, then you will never pass. I just went through the same smog hassle you are going through. I bit the bullet, and popped ($280) for a brand new Edelbrock Performer 750 CFM carburetor for my 1985 K30 with a 454, and my truck passed smog with flying colors.

    Unless you "degree in" (with a degree wheel) an aftermarket cam to "true TDC", the only way you can properly set the ignition to valve timing is with a vacuum gauge (a timing lite will not do it) because aftermarket camshafts are not indexed to a factory crankshaft when ground, like a GM factory camshaft is. When you connect the vacuum gauge to a "MANIFOLD" vacuum source, advance the distributor until you reach max vacuum reading, then back it off 1/2-inch of vacuum, this will be the most efficiant timing you can get. If you have to retard your timing more than this to pass smog, then there is somthing more wrong with your engine, which is causing it to not perform as good as it should.
     
    Last edited: May 23, 2006
  19. 78Suburban

    78Suburban 1/2 ton status

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    Good luck with that emissions crap, I've got my fingers crossed for ya ;)
     
  20. 4xcrazy

    4xcrazy 3/4 ton status

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    this is the exact plan right here,,,i was so brain farted and dead yesterday, i just couldn't think straight anyways, now i am rested, when i get back from a light day of work, gonna tear into this..

    will let ya know how it goes when finished,,thanks for the replies:D
     

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