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Quadrajet adjustment,....secondaries?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by twenty_below0, Feb 25, 2002.

  1. twenty_below0

    twenty_below0 1/2 ton status

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    Ok put the Q-jet on today and I must say....I like it!! much smoother and better off the line but it suffers on the mid to high end so I'm wondering what to do to improve this like how to adjust the opening time of the secondaries and maybe a jet adjustment or something........haven't worked on these that much?? Also it seems to kind of stick on about 1500 rpm's themn you stomp the gas QUICKLY and it stops, but it starts again if you give it the gas, then when you try to stop it tries to keep going and so you have to hit the pedal again to get it to quit...how do I solve this dilema? THX
     
  2. Triaged

    Triaged 1/2 ton status

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    try
    http://www.dorianyeager.com/indexquad.html

    '71 Blazer CST w/ a 400sbc, 4" lift, 36" Supper Swampers, and alot of rust
    <a target="_blank" href=http://community.webshots.com/user/triaged>See it Here </a>
     
  3. twenty_below0

    twenty_below0 1/2 ton status

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    THX for the info,what about the little screw on the end of the secondary shaft at the bottom of the carb??is this the screww you adjust to change the opening pointor time of opening??and do you have any idea's on why it's idleing so high and you have to stompit?
     
  4. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Sounds like the fast idle linkage is sticky...a liberal spray of carb cleaner should help that. For top end performance I've heard of using the metering rods from a Corvette Q-jet. They have a much more agressive step in the metering rod allowing more fuel flow at WOT. A friend of mine spent many weekends experimenting with different metering rods to get his where he wanted it.

    Rene

    <font color=green>Dyslexics of the world...UNTIE!</font color=green>
    <a target="_blank" href=http://coloradok5.com/gallery/project_T2> tRusty pics...</a>
     
  5. twenty_below0

    twenty_below0 1/2 ton status

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    THX for the response Rene, could you give me some specs as to what his sbc has for h.p. and torque so maybe I could use the same rods as he did if our engines compare, I know the balls have sure left my k5 after 3,000 rpm's, and the secondaries are opening just not enough fuel being delivered I believe, also how hard is it to start changing the rods and jet's etc. THX Mike
     
  6. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    The spec's I remember aren't very specific, this guy was someone i worked with about 3 years ago. The car was an 81 Camaro which was running low 13's at sea level. I have no idea what cam he was running, but the heads and intake had been port matched as well as some other work done for better top end flow. It had headers and good free flowing exhaust, but cam, CR etc I have no idea.

    The metering rods hang off the arm for the secondaries and IIRC all that needs to be done to swap them is to remove the top of the carb and hang some new rods...

    I'd make sure the choke mechanism isn't preventing the secondaries from opening first of all. If there is nothing preventing the secondaries from opening I'd do the secondary adjustment found on Dorian's link. I'd only go as far as swapping metering rods if everything was working right and it still seemed weak. All the guy told me was the metering rods were early 'Vette. He had quite a collection in his toolbox and showed me the differences between the various rods. Mostly the 'step' was more pronounced and obvious on the 'Vette rods.

    Rene

    <font color=green>Dyslexics of the world...UNTIE!</font color=green>
    <a target="_blank" href=http://coloradok5.com/gallery/project_T2> tRusty pics...</a>
     
  7. dyeager535

    dyeager535 1 ton status Premium Member

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    If you look at the links in the previous post, you will find out most of the info. Engines vary so much that you wil have to just play around with them. It takes about 2 minutes to swap them.

    Take the air cleaner and its stud off to change the secondary metering rods/hangar. (been awhile, but I think the stud kinda gets in the way) One screw (either flathead or torx on later ones) holds the hangar/rods in place.

    I had the opposite problem on my car, I was dumping too much fuel and at the higher RPM's I was running out of gas. I played around with different rods/hangars until the problem was non-existent, but right on the edge.



    Dorian
    My tech/links page: <a target="_blank" href=http://www.dorianyeager.com/index2.html>www.dorianyeager.com/index2.html</a>
    Why insist on counting when the ring gear has the tooth counts stamped in?
     

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