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V6 Cylinder Head Emissions Ports

Discussion in 'Early CJ5 and CJ6 Tech' started by maurywhurt, Nov 18, 2019.

  1. Nov 18, 2019
    maurywhurt

    maurywhurt Member 2019 Sponsor

    Western North...
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    I have a question about the so-called emissions ports in the Dauntless V6 cylinder heads. I'd previously thought that these ports were present on the later V6's, as opposed to the early ones. However, when I posted these photos yesterday Factory Engine Bay Photos?, I noticed that this very original unmolested V6 (with less than 3k miles on it) that dates from late 1965 has these port plugs.

    Apparently all the Dauntless heads had them - but 1965 was several years before emission control measures were required on American cars. These ports were probably a hold-over from Buick's early 1960's design, but why would emissions ports have been present at such an early time frame?
     
    Last edited: Nov 19, 2019
  2. Nov 18, 2019
    oldtime

    oldtime oldtime

    St. Charles,...
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    I believe there are some early Dauntless heads without having those ports.
     
  3. Nov 18, 2019
    47v6

    47v6 junk wrecker! 2020 Sponsor

    Washington DC.
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    My 1965 buick 225 odd fire v6 skylark engine does not have them
     
  4. Nov 18, 2019
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    FWIW my FSM purchased in '69 from Jeep shows a V6 head that doesn't have those.
     
  5. Nov 18, 2019
    maurywhurt

    maurywhurt Member 2019 Sponsor

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    Interesting...then evidently the emissions ports were not a carry-over from the Buick design. And it sounds like there's evidence that the earliest Dauntless heads didn't have the ports either.

    But if they had no apparent use until years later, why would the ports have been cast into the heads of the early '66 Dauntlesses (like the one in the photos linked to in my first post above, which was built in Oct. '65)?
     
    Last edited: Nov 19, 2019
  6. Nov 18, 2019
    Keys5a

    Keys5a Sponsor

    Florida Keys
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    I had a '67 Jeepster that did not have those ports. The next time I get up to NC I will get some pictures of the heads.
    -Donny
     
  7. Nov 18, 2019
    mrtii

    mrtii 1972 cj51986 cj7 2019 Sponsor

    gilroy, California
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    California was the first place in the world to regulate vehicle exhaust emissions. Air injection was mandated for all California passenger vehicles with manual transmissions in the 1966 model yr. which would begin in sept 1965
     
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  8. Nov 18, 2019
    Glenn

    Glenn Kinda grumpy old man Staff Member

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    I wonder if lower compression was part of the equation.
     
  9. Nov 18, 2019
    Mcruff

    Mcruff Earlycj5 Machinist

    Albertville, AL
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    Smog pumps started on the 1966 model year in California so a vehicle built in late 1965 could have had the heads installed simply because that what was available at the time or it may have been built as a California vehicle that never made it there.
     
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  10. Nov 19, 2019
    fhoehle

    fhoehle Sponsor

    Harford Township, PA
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    No emissions ports on Farm Jeep Willy or the spare heads in the shed if that adds to the discussion.
     
  11. Nov 19, 2019
    maurywhurt

    maurywhurt Member 2019 Sponsor

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    This is no doubt the reason the emissions ports came into being during that particular time frame.

    Thank you for solving this little mystery!
     
    Last edited: Nov 19, 2019
  12. Nov 19, 2019
    mrtii

    mrtii 1972 cj51986 cj7 2019 Sponsor

    gilroy, California
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    Lower compression did become part of the solution but not instill the 1971 model yr when NOX regulation took hold and new head design lowered compression significantly
     
  13. Nov 19, 2019
    Vanguard

    Vanguard Chief Cook and Bottlewasher Staff Member

    Brighton, MI USA
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    I think the most likely scenario is that the heads have been swapped. May even be even-fire heads. If you want the details, find the casting number on the heads and look here -

    Buick V6 Casting Numbers
     
  14. Nov 19, 2019
    mike starck

    mike starck Member 2019 Sponsor

    salem,oregon
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    I believe the lower compression ratio is because of the design of the piston (dished vs flat top) rather then the head design .That came about with the redesign of the 225 to the reintroduced GM 231 engine
     
  15. Nov 19, 2019
    Buildflycrash

    Buildflycrash Member 2020 Sponsor

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    Is that the difference?. Dished pistons gave a larger displacement number?
     
  16. Nov 19, 2019
    Keys5a

    Keys5a Sponsor

    Florida Keys
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    No, dish pistons don't increase displacement. Bore x stroke x # cylinders = displacement.
    Most 225 odd-fires have dished pistons, some more dished than others to lower compression ratio. There may have been a Buick verient that had flat top pistons.
    The 231 standardized bore sizes with Buick's V8s so they could share parts, increasing displacement in the process.
    -Donny
     
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