"Q-Jet" question on the "Vacuum-Break Diaphragm"

Discussion in 'General Tech' started by bugzaper, Oct 5, 2018.

  1. bugzaper

    bugzaper Well-Known Member

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    So...I'm playing around with the "Q-Jet" on my warmed over "425" and found that the "Vacuum-Break Diaphragm" is not working.
    It will not hold the arm in place when depressed and plugging the small little hole.
    I actually removed the choke plate many years ago.
    I was reading that the "VBD" was not only used to pull the choke plate open but, it is also used to keep the secondary plates from slamming back shut after opening.
    This is the first time I have learned this and was wondering if I need to replace it or can I just remove it all together.

    (see pics.)
     

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  2. bugzaper

    bugzaper Well-Known Member

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    few more pics.
    (dist. vacuum line is a dummy--no vacuum from that port...)
     

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  3. PJ McCoy

    PJ McCoy Active Member

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    Replace it. I believe it also keeps the secondary air valve from opening when it's cold. If memory serves right.
     
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  4. bugzaper

    bugzaper Well-Known Member

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    "Yes" after reading and doing a bit more research I agree and ordered one from "Cliff's Q-Jets."
     
  5. bugzaper

    bugzaper Well-Known Member

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    Time to pack it up and ship it off to "Cliff."
    (tired of messing with it...)
     
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  6. Darius

    Darius Well-Known Member

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    It gets to that point at times. And why the heck Not send it to someone who knows what to do? Your time, and frustration levels, are worth something. Just ask you wife!

    bro. d
     
  7. Monzallac 425

    Monzallac 425 Member

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    Holley has a new Quadrajet EFI that bolts on any GM stock spreadbore manifold.

    Check it out on YouTube.

    Doug in P.R. :)
     
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  8. bugzaper

    bugzaper Well-Known Member

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    ...carb man and too old to change now. :thumbup:
     

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