Nailhead question

Discussion in ''Da Nailhead' started by Lobucrod, Oct 6, 2020.

  1. Lobucrod

    Lobucrod Well-Known Member

    Did all 66 Single 4 barrel nailheads have q-jets or did some come with AFBs?
    Or was the q-jet only available on the 425?
  2. Babeola

    Babeola Well-Known Member

    The 66 400 could have a Carter AFB or an optional (A9) Rochester 4MC (Quadrajet). The 66 401 could have a Rochester 4GC (Square Bore) or Carter AFB. The 66 425 could have a Rochester 4MC (Quadrajet) or optional (A8) dual 4 barrel Carter AFBs.

    Cheryl :)
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  3. Stevem

    Stevem Well-Known Member

    In 66 GM across the board was starting to intigrate in the Q-jet on motors that would still be made come 1968.
  4. SubCool

    SubCool SubCooled

    Interesting that the 4GC was an available carb in 66 on 401 engines. Every 66 401 I've ever seen had an AFB.
  5. PGSS

    PGSS Well-Known Member

    The 66 401's with the 4GC were standard on the Wildcats and Electra's. The 66 Skylark GS came standard with the 625 cfm AFB and the high output option had the Q-jet.
    I'm guessing your 401's with AFB's had to be swapped on unless your 401 car's were Skylark GS's, I believe the 65 Skylark GS also had a AFB
  6. Babeola

    Babeola Well-Known Member

    The 66 4GC was available on 401s with an auto trans. The 66 AFB was available on 401s with a auto trans, manual trans or use in California. They are all listed with separate part numbers/labels for the 401 in the 66 CSM.

    Cheryl :)
    Last edited: Oct 17, 2020
    PGSS likes this.
  7. SubCool

    SubCool SubCooled

    Huh,learn something new everyday
  8. PGSS

    PGSS Well-Known Member

    Totally believe you but do you have a link to the CSM, or do I just look up Chassis Service Manual?
    Might be interesting reading..
  9. Babeola

    Babeola Well-Known Member

    I have a well worn hard copy here amongst others. It should be a bible for those considering any DIY evaluation or repair. There are modern day consideration, but it is still the best place to start looking for information. Here is a link to the 66 CSM over on You may have to join to look at it. I know the site owner would like a small contribution if you find it useful. It was a lot of work to scan all the CSMs there.

    Cheryl :)
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  10. PGSS

    PGSS Well-Known Member

    Wow I went to and couldn't find this one link.. Thank's Cheryl for making it easy.:)
    Will do with a contribution;) All these forums make it so much easier for us.. It's only right..!

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