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Carbs/Vacuum lines and other questions HELP!!!

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Hathaway, Jun 6, 2001.

  1. Hathaway

    Hathaway 1/2 ton status

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    Ok, so I got the blazer running again. It was idling WAY to slow. I fidled with the carb (quadrajet) and got it running but I had it idling too fast. So my dad go it going ok while i was at work. Now, he found a bunch of the vacuum lines around the carb busted/melted/cracked and the like. Should I just go through the whole car and replace every vacuum line or just the few bad ones I can see? Also, the secondary barrels on my carb never open up. I can mash the peddle and haul arse down the high way and they never open up. Why is that? My choke is also sticking. But the good news is that the K5 is back up and running and on its way to running GOOD. I'm thinking of picking up a Holley as I know a guy with a Yota that has a 305 swapped in with a Holley and has had good experience with it. So any advice on the vacuum lines or adjust the carb is appreciated.

    Next I get to go to the local bone yard and try and find a K5 with a salvagable floor as mine sure isn't. they said they'd cut it out for me then me and my boss are gonna weld it in. Follow that up with dropping the Tcase for new shift fork/bushings and add those Warn manual locking hubs over the autolockers and it should be ok for a while [​IMG]

    Dan, '86 K5, 5.0L v8, NP208, TH700R4, open 10bolts front and rear, 3.43gearing, K&N filter, 31x10.50R15 Trailhandlers
     
  2. 2Dogs

    2Dogs 1/2 ton status Premium Member

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    Replace all the cracked vacuum lines for sure.
    Stick with the Qjet - good power and low maintenace carb.
    I think the qjet has a mechanical secondary - check the external linkages for connections. Do the secondaries open up in the WOT position with the engine off?
    Dave
     
  3. Pugsley

    Pugsley 1/2 ton status

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    I'd go ahead and replace all the vacuum lines. The Quadrajet is about the best carb you can get, so stick with it.

    I'm so poor I can't even pay attention [​IMG]
    <A target="_blank" HREF=http://pugsley.coloradok5.com>http://pugsley.coloradok5.com</A>
     
  4. xnoahx

    xnoahx 1/2 ton status

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    Go buy a can of carb cleaner and use it like it says to on the can, its supposed to free up the linkages and clean it all up. also, how do you know the secondaries arent opening, are you just gunning it in the driveway or have you rigged them shut and driven it because they wont open unless there is load on the engine. The Quad is a great carb. Also make sure the timing is right on

    Check out my 73 K5 http://members.theglobe.com/xnoahx/73k5.htm
     
  5. Hathaway

    Hathaway 1/2 ton status

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    OK I figured the comment on changing carbs would get some responses.. [​IMG]. So here goes...

    The secondaries NEVER OPEN. My dad fiddled around with it yesterday while I was at work so I'm not 100% sure how he did it but he's owned enough carbed vehicles that he knows what he's doing. Second, I did use carb cleaner on the beast. It did jack squat.

    I still think I'm going to switch to a holley. After reading the recent tech articles in Four Wheeler and Peteresens about Carbs and hearing that Willie Worthy(who lives about 15minutes from me) runs a Holley on his 383 I'd trust em. Also like I said in the original post, a guy that works with my dad has a 305 swapped into his 'Yota with a Holley on it and that thing is a beast. I'll be checking the timing this weekend when I do my oil change/spark plugs/plug wires/all that crud.

    Dan, '86 K5, 5.0L v8, NP208, TH700R4, open 10bolts front and rear, 3.43gearing, K&N filter, 31x10.50R15 Trailhandlers
     
  6. 2Dogs

    2Dogs 1/2 ton status Premium Member

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    How much off-roading do you do? I think the qjet is much better (can be modified?) for of-road conditions. Holleys are for street.....
    Dave
     
  7. Zepplin

    Zepplin 1/2 ton status

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    Ok, ok. I had the exact same problem. My secondaries were seized shut. After I took it apart I found that the secondary butterflies would not open. I had to tap them open with a hammer lightly. A few things could cause this; the bar that the butterfiles are attached to could be bent, the carb base plate where the secondaries are attached to could be warped. Or bent likages or it is just plain gummed up. A carb could get warped by some joker using an impact gun to tighten down the carb to the intake.

    So I was driving around on 2 barrels, black smoke coming out of the tailpipe because it was too rich and I had absolutely no power when I hit the gas.

    Don't get a Holley because they suck on an off-road vehicle. My friend had one on his Heep with a 350 on it and he always stalled it on hills and chatter bumps. Take apart the carb completely clean everything up, check the linkages, replace all the rotted vacuum lines and replace all the gasekts, etc.

    Mine runs like I have a brand new engine under the hood!
    Also, make sure you're not drinking your coffee when you hit the gas because you will have it all over ya!

    74 Blazer
    Zepplin
    Current pictures of my Blazer: <A target="_blank" HREF=http://www.jeremyb.coloradok5.com/photo.html>http://www.jeremyb.coloradok5.com/photo.html</A>
     
  8. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    First, replace all vacuum lines whether they look rotted or not. One bad line (even if it looks good) can cause lots of problems, especially with carb adjustment. Plus vacuum line is cheap.
    Second, Holley's are not a good carb for off kilter situations. Edlebrocks are a little better as well as AFB, but the Q-jet is still one of the best carb's. Of course a new Holley carb will outperform a old used Q-jet. But side by side brand new, I feel the Q-jet is a better suited carb for everyday driving and/or wheeling. Your carb probably is old and seen many miles as well as shi# mixed in with your gas and shallack. As with any carb, over a long enough period of time and lack of PROPER maintainance, it's performance will deteriorate. Spend the money to get the carb rebuilt by someone who knows what they are doing. The metering rod setup I feel is much better than the jet setup of the Holley, plus the whole Holley float issue in off kilter situations flooding the engine can be a pain. In the end you will do what you want, but remember the Q-jet was originally designed to work with your motor. Bringing it back to like new with a COMPLETE (meaning choke too) and PROFESSIONAL rebuilt will get you all the performance a carb can, and it should cost about the same or less. Even if it costs a little more, you will still have a better off-roading carb than a holley.
    This is my own personal opinion from experience, had a Q-jet (running poorly), bought a Holley (fuc#ed with it forever), rebuilt the Q-jet and have been happy ever since. Plus alot of guys say when a Q-jet performs the way it should, you can't beat them.

    If you didn't built it yourself, how can you call it yours.......?
     
  9. dyeager535

    dyeager535 1 ton status Premium Member

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    Even if someone knows carbs, doesn't mean they know q-jets. If, given what you describe is correct, the choke is not opening all the way, the secondary lockout on the passenger side of the carb,(located here on all but early 70's Q-jets) will not allow the bottom throttle plates to open. Do not remove that lockout, FIX THE PROBLEM, which is the choke.

    Also, the secondary throttle plate (that would be the bottom "butterflies" on the secondaries SHOULD open, even with the engine off, IF the choke is fully open (IE truck warmed up). The top "butterflies (actually called the secondary air valve) will not open when the truck is just sitting and you rev the gas. You can take that thing to 6000RPM and it MIGHT start to open. The secondaries are held SHUT with vacuum, not open, so with no load on the engine (IE if its not moving and in gear) they will NOT open. As well, the secondaries, once vacuum has dropped off, are opened, and held open, by in rushing air. As vacuum increases (less throttle) vacuum returns, closing the secondary air valve, as well as the decrease of inrushing air.

    I added an exploded view of the Q-jet on my page lsited below under the Q-jet tech area if you need an idea of what pieces I am talking about.

    Dorian
    My tech/links page: <A target="_blank" HREF=http://www.dorianyeager.com/index2.html>http://www.dorianyeager.com/index2.html</A>
    No anti-theft measures on your truck? No pity when its stolen
     

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