How to modify a 1969 QJ to become a 1970 455 Stage1?

Discussion in 'The Venerable Q-Jet' started by Cutlass, Nov 11, 2018.

  1. Cutlass

    Cutlass Platinum Level Contributor

    My clone has a stock 1969 QJ installed.
    Can the internals be modified, so that it performs like a 1970 Stage1? If so, what needs to be done?
    I attach a pic of the QJ with the ID, in case that might help with the answer.
    THX IMG_3456_low.jpg
     
  2. flynbuick

    flynbuick Super Moderator Staff Member

    A 70 Stage I carb has topside squirters. I am not sure how you could replicate those without the correct carb.
     
  3. Bigpig455

    Bigpig455 Fastest of the slow....

    Short answer, yes. Talk to Ken at Everyday Performance (TechG8 here on the board) It's all a matter of sizing idle and air bleeds, primary and secondary rods and jetting. But more importantly is building it to perform on your specific vehicle - understanding what transmission, operating temps, fuel system, exhaust, cam and gears you've currently got. You'll wind up with a carb that runs much BETTER than if you just stuck a Stage One 246 on there.....
     
  4. HotRodRivi

    HotRodRivi Tomahawks sighted overseas

    Wat are topside squirters?
     
  5. 72STAGE1

    72STAGE1 Runnin' with the Devil

    Get one already rebuilt and use a 850 CFM from 1972 up. It allows you a broader palate to work with in the future for any up-gtrades you might do.
     
  6. Cutlass

    Cutlass Platinum Level Contributor

    Got good stuff (Jets, Rods,.... and a complete rebuild kit) from Ken, brought it back home yesterday, but will have to wait until spring to see results. Will give feedback once installed
     
  7. 72STAGE1

    72STAGE1 Runnin' with the Devil

    You are on the right path, I rebuilt my 72 Qjet per Cliff Ruggles book and have been very please ever since. Most guys won't tackle these so thumbs up to you for being a hands-on GS owner!
     
    Brett Slater, TexasT and techg8 like this.
  8. Stevem

    Stevem Well-Known Member

    You should be more concerned with fuel delivery and fuel temp To the Carb for starters then fuel and air thru the Carb !
     
  9. hugger

    hugger Well-Known Member

    Actually the the rear bore fuel enrichment passages are under the doors on a stage 1 and 4speed carbs, the standard q jets have them above the rear air door
     
  10. Bigpig455

    Bigpig455 Fastest of the slow....

    True, so visually those in the know will always be able to tell the difference. But for the sake of function, you can notch the secondary air valves and achieve the same effect....
     
  11. Cliff R

    Cliff R Well-Known Member

    There are other items used for the Stage 1 carburetors that are not the same as the "grocery getter" units. Same deal going on with the Pontiac "Ram Air" carburetors.

    You can use parts and make modifications to them to get them to work well, but they are still not the same as the real-deal.....FWIW......Cliff
     
  12. Cutlass

    Cutlass Platinum Level Contributor

    Took some more pics from my carb. Is the discoloration within the orange circle a hint of a worn out shaft?
    IMG_3728_low.jpg
    Also, there is a 12V source going to the divorced choke. I thought, that the divorced chokes worked with engine heat only. Is this an aftermarket solution?
     
  13. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    No, that discoloration is an indication of nothing:). If you can wiggle the shaft, it is obviously worn. Spray some carb cleaner at the shaft with the engine running and you'll quickly see and hear if there is a big vacuum leak there.

    There is no 12 volt source to the choke, not a stock one anyway. Not sure where that came from, maybe a later model.
     
  14. lemmy-67

    lemmy-67 Gold Level Contributor

    The divorced choke rod connects to a bi-metal coil which sits in that well in the intake manifold, and is actuated by heat from the exhaust crossover. That 12V wire controls nothing. It should go to an electrostatic choke, which this carb obviously does not use, and may be left over from a previous setup with a E4ME Rochester carb.
     
  15. Cutlass

    Cutlass Platinum Level Contributor

    Had a couple of hours to work on my carb.
    At first I started with the plugs. Not only did the repair look terrible, two of them actually showed leakage.
    IMG_3853_low.jpg
    First I pulled the plugs
    IMG_0082_low.jpg IMG_0088_low.jpg IMG_1610_low.jpg
    Then I cutted threads and fabricated plugs
    big ones:
    threading, drilling for forming the hex, cutting to length and forming the hex with my 20to press
    IMG_1625_low.jpg IMG_1633_low.jpg IMG_1634_low.jpg IMG_1635_low.jpg
    small ones almost same process, but slotted with my "professional" slotting device :)
    IMG_1662_low.jpg
    Final result after fastening the plugs with Loctite 542
    IMG_1666_low.jpg
    Next I am starting on the baseplate, but unfortunately one of the screws holding the flab on the shaft was stuck (corrosion), so that the head came of (flush to the rod). I will have to drill it out and see if I can save the original 3-48 thread.

    Good things happen as well, after taking the shaft out I was happy to see that the previous owner already had installed bushings.
    To be continued....
     
    Last edited: Jan 21, 2019
  16. BuickV8Mike

    BuickV8Mike SD Buick Fan

    Very nice work Ralf. Watching and learning.
     
  17. techg8

    techg8 The BS GS

    Great work on the plugs!
     
  18. Cliff R

    Cliff R Well-Known Member

    We sell a plug kit with 6 small plugs and two large ones already the correct size/length and it comes with Marine Tex.....for those who don't have a complete machine shop.

    Make sure the bushings are thick wall bronze, not thin wall brass. The thicker wall self-lubricating bushings are the better repair and after another 50 or so years of use will still show less than .001" side play.......Cliff
     
  19. Cutlass

    Cutlass Platinum Level Contributor

    How do I find out? What is the outer diameter of the bronze versus the brass?
    Of course your plug kit will work as good. It is however somewhat inconvinient to get stuff over here (time & money) and on top of things I just like fabricating my own stuff as much as my skills and my workshop allow for.
     
  20. lemmy-67

    lemmy-67 Gold Level Contributor

    Some re-manufactured Q-Jets (like the one on my Buick when I bought it from the original owner) have thin brass sleeves on the throttle shaft holes instead of the beefy pre-oiled bronze bushings which fit to much tighter clearances. Those brass sleeves are crap, and do nothing to stop the vacuum leaks from the throttle shaft. I took the throttle shaft out of this particular carb, it leaked like hell, and saw those thin brass sleeves in the bores. I drilled them out, tapped in the new bronze parts from the kit, and the performance was 100% improved.

    It's really a design flaw (steel shaft spinning up/down + in hole of aluminum base plate = worn aluminum & big hole for vacuum to leak) of the baseplate/throttle body. GM/Rochester Prod. Division tried to fix it by coating the shafts with teflon (green stuff on later Q-Jets), but the only solution is to install the bronze bushings which hold oil and properly seal the throttle bores. The primary shaft is always opening & closing, where the secondary only moves when the driver really nails the throttle, so the primary shaft always wears out first.

    Just get the kit, install the bushings, and voila: no more vacuum leaks. If you have a good drill setup, the whole thing takes 20 minutes.
     
    Brett Slater likes this.

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