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  1. #1

    Default 4180C and Ca emissions.

    Hey guys, new subscriber here. I just bought a 1985 Mustang GT and I am having issues with it passing smog. The car is failing on HC ppm and CO% at 15mph and 25mph. Here are the readings

    Reading Limit
    HC ppm 425 97 at 15mph
    CO% 7.56 .59

    HC ppm 432 79 at 25mph
    CO% 8.04 .45

    I took the 4180c carb apart and the main jets are stamped 279 and the power valve has F2 and 10 stamped on it. Are those the factory size parts? If they are, what other reasons may cause the carb to run rich. As far as I know all the vacuum hoses and egr stuff is on and plugged in. I am running the cats off of my 88 on this car. Any help would be appreciated.

  2. #2
    FEP Senior Member
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    hi, what i did was i bought an AFR so i could tune my carb to pass emission. in my state i must run E10 which this car was not designed to run on. with a lot of miles on it i needed to rering the engine (to much oil) and then install new cats to get the car to pass. good luck

  3. #3
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    Wish I could help more but I haven't seen those jets mentioned regarding any Mustang carbs. I think there were 622's in the last version of that carb in '85. I also can't recall how the 2 stage PV's were stamped.

    What are the "pass" numbers/specs/standards for your car?

    In addition to the general rebuild/carb cleaning, make sure that all of air bleeds on the top of the carb are clear all the way through. A paper clip bent straight will do the trick. When I did that to mine I felt the paperclip break through the blockage. Not saying this would fix your issue but it could be a free fix. You could also try to lower the float level in the primary to lean it out some.

    FYI, there is really good 4180c info all over this site but you'll have to use google to find it as the forum search isn't so good.

    Here is some info about '85 cat's that might be helpful at some point.
    http://vb.foureyedpride.com/showthre...-with-an-85-GT

    There are also a bunch of threads here about various adventures with CA smog testing. Again, you'll have to find the info using google.
    '85 GT

  4. #4

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    Thanks for the info guys. I have a repair kit on order. I'm gonna have to really get into the weeds with this issue. LOL! More to come.

  5. #5
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    FYI, the Holley rebuild kit will not come with any jets and will not come with a 2 stage power valve. It will be very difficult to find close limit jets and anything but single stage PV's. Frankly I wouldn't bother looking for either.

    Keep us posted on how it goes. Also, welcome to the site!
    '85 GT

  6. #6
    FEP Super Member xctasy's Avatar
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    Close limit jets exist on many Holley 4180C carbs. They stay in calibration. Anything related to the IM test is most likely gas quality and the need to preheat before testing. CA IM tests can be discussed adequately on Facebook under this group.

    I've found it excellent.

    Californians for Classic Car Smog Exemptions.

    In my opinion, #acebook is resolutely trash, except with groups like this. They posts there problems, and people brainstorm solutions.

    On Four Eyed Pride, check with the Carb guys who say California Emissions is broken. Then do what they did, to get there car through the IM tests.

    Generally, the
    AIR,
    EGR,
    catalysts
    and Hot Idle Correction circuit on the fuel line,
    along with the crank pulley elastomeric seal changing the idle degrees,
    the variable reluctor in the Duraspark II,
    and aspects of the Two Speed Accessory drive, which does funny things to the Barometric Air Pressure sensor to play with timing,
    and the passenger side multiple element altitude compensator line, and it's impact on the Emissions Purge for the vapor canister

    ( see '
    http://vb.foureyedpride.com/showthre...nister-missing
    ' )

    You've literally got 93 systems in an 85, and as long as you don't have a hose defect, or a wrong setting, then it's just fuel treatment and catalyst and engine pretreatment by proper heating before testing.

    From what I've read, the reason smog techs dislike the carb pre OBDII cars, it's that ,they don't self check with a 25 and 50 thou leak valve on the EGR and AIR and evaporative emissions circuits, and they don't wire 60 cycling items to every fuel flap and sensor and pop out a list of four digit codes like the post 1995 cars do. So if an IM test passes your car, and a roadside smog camera finds the car belching too much Nox, guess who gets there smog records vetted. And carb cars have to present as being genuinely Unmodified, with stock everything. Anything non standard, it's a massive risk to the guy doing the testing.

  7. #7

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    Quote Originally Posted by G50Stang View Post
    ....I took the 4180c carb apart and the main jets are stamped 279 and the power valve has F2 and 10 stamped on it. Are those the factory size parts? ....
    That number stamped on the jet is not a Holley jet number that I'm familiar with. I believe Holley jet numbers range from 40 to 208.
    1985 Mustang GT (Mothballed...Desired restomod parts acquired...Top of my project list for my 2024 retirement!)

  8. #8
    FEP Senior Member
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    As an 85 owner and CA dweller, I feel your pain.

    Its hard to get our machines to pass the test anymore, especially on the chassis dyno that you're having to use. Good news is you're not having trouble passing visual. The catpipe you're running has provisions for an O2 sensor, so installing a wideband and monitoring your air/fuel ratio is your best bet. I had to do this multiple times at my last smog check. Everything has to be near perfect for it to pass.
    85 Saleen Mustang(s)

  9. #9

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    Quote Originally Posted by G50Stang View Post
    Hey guys, new subscriber here. I just bought a 1985 Mustang GT and I am having issues with it passing smog.
    Is the car originally a 49-state emissions car or Cali-emissions car?


    Quote Originally Posted by G50Stang View Post
    I took the 4180c carb apart and the main jets are stamped 279 and the power valve has F2 and 10 stamped on it. Are those the factory size parts?
    After a little research, it appears (not a guarantee though) that the stock primary jets are size 64. Don't know if Cali cars were jetted different than 49-state'ers though. Didn't research power valves any.


    Quote Originally Posted by BaconB8 View Post
    The catpipe you're running has provisions for an O2 sensor, so installing a wideband and monitoring your air/fuel ratio is your best bet. I had to do this multiple times at my last smog check. Everything has to be near perfect for it to pass.
    That's a great idea!
    1985 Mustang GT (Mothballed...Desired restomod parts acquired...Top of my project list for my 2024 retirement!)

  10. #10

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    California does not have age limits on pollution requirements? A good way for FORCE you into an electric car.....

  11. #11
    FEP Power Member
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    CA does have age limits on emissions. Its 1976 and newer get smogged. They ignore the 1966 to 1975 cars. The plan seems to be eliminate the gas stations. I think no new ones starting like 2035. Of course no new gas powered cars by then as well.
    Fox Body/3rd Gen MCA Gold Card Judge
    84 SVO 24K miles, 85 Mclaren Capri Vert. 84 GT Turbo Vert.
    88 Mclaren Mustang Vert 20K miles, 89 Mustang LX Sport Vert,
    03 Mach 1 7900 miles, 74 Mustang II, 69 Mustang, 67 Mustang, 07 GT500,
    14 Mustang CS/GT, 15 F150 FTX Tuscany, 16 F250 Crewcab, 67 Tbird 47K miles

  12. #12

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    85GTGuy is correct about the jet numbers. My 85 came with 61s and ran lousy at off idle throttle. I bumped them to 63s and solved the problem. No smog test for the county I live in thankfully so I don’t have that problem. Go to Summit Racing and order the small set of jets 60-69, ~$50. Search for Holley Jets. That should get you leaned out. I’m at an elevation of 1100’. If you are closer to sea level you may need to go higher than 61.
    W

    As always, "It ain't what you don't know that gets you, it's what you think you know that just ain't so."

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