800 cfm Quads Buick?

Discussion in 'Engine Topic' started by Randy Doubosiff, May 20, 2019.

  1. cadillac_al

    cadillac_al Veteran Member

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    You will need some kind of spacer to get that straight inlet to clear the thermostat housing on a Chevy.
     
  2. tom3

    tom3 Veteran Member

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    They will work on the Chevy but (from what I've seen) they are jetted way off for a small block. Will need to change rods and jets in the primaries and see how it goes in the back. Those big cube motors suck a lot of vacuum and the jets are pretty small actually. And can be a big old complicated carb for a nice simple install.
     
  3. jeff swisher

    jeff swisher Veteran Member

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    I have some and ran them on my SBC engines and with ported heads the AFR was not too far off.
    Not far enough off to make any hiccups for a bolt on deal.
    The primary venturi is larger in the 800 something many people overlook is how far the secondary air valve door is opening.
    GM did much trickery there. You will not get the full flow these Q jets are capable of if the door is only partial opening because of the stop on the side.

    They used the 800CFM on the early carbed turbo blow through at least in 1 Buick a fiend had.
    But the secondary air valve would open about 1/2 way.

    That carb had the least amount of secondary airvalve opening of any Q jet have seen.

    400 pontiac in 1977 I know had the 800.
    Something i look for more than 750vs 800 is the position of the hole for the secondary enrichment
    POE holes (pull over enrichment)
    Some holes were way above the secondary air door some were right next to the door some were split and some of the holes were below the air valve door like 1970 Buick stage 1.

    You can plug and redrill the holes to make secondary transition much quicker and smoother.
    Fun with Q jets :)

    I have seen some of those fetch $1500
     
  4. 1980RS

    1980RS Veteran Member

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    The 800 Q-jet I have came off a 454 engine, that's why I saved it.
     
  5. SRGN

    SRGN Veteran Member

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    Buick Q-Jets are set up for a divorced choke, and as mentioned the fuel in let location is different. Check the numbers, Buick guys are always looking for those carbs.
     
  6. 77 cruiser

    77 cruiser Veteran Member

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    All the late ones are 800.
     

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