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Hot Rods Need help adjusting my stromberg

Discussion in 'The Hokey Ass Message Board' started by jjjmm56, Mar 26, 2019.

  1. jjjmm56
    Joined: Feb 7, 2009
    Posts: 531

    jjjmm56
    Member
    from FL.

    I’ve got a 303 with 3 stromberg 97’s. I was wanting to use the middle as primary and two as secondaries. The motor is a new build, starts and idles fine, but looks to be running a little rich. When giving it gas it wants to stumble all over itself. I’m not sure if I need to shut off the idle circuits on the secondaries before adjusting idle circuit on the primary, because turning the mixture screws do not change how the engine runs. I also disconnected the linkage to the secondaries. I’m not sure what my main jets are I’ll check them tomorrow. Running 2 1/2 lbs to the carbs and the air cleaners off. [​IMG]


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  2. u using a unisyn to balance the carbs???? progressive or straight linkage, start out with idle circuits out 1 1/2 turns turn each one closed till engine starts running rough, back off 1/2 turn your done move to other screw and repeat process....
     
  3. alchemy
    Joined: Sep 27, 2002
    Posts: 20,407

    alchemy
    Member

    Idle circuits in secondaries are unnecessary aren't they? You should make sure your throttle plates on those secondaries are closing tightly. And, those air cleaners might be cool, but they don't look like they'd flow much air.
     
  4. jjjmm56
    Joined: Feb 7, 2009
    Posts: 531

    jjjmm56
    Member
    from FL.

    Air cleaners are off. Even with the secondary throttle plates closed it’s still pulling the slightest amount of air. I did the whole 1 1/2 turn thing and in and out but motor will not start running rough. I’m trying to get an answer about the idle circuits on the secondaries.


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  5. jjjmm56
    Joined: Feb 7, 2009
    Posts: 531

    jjjmm56
    Member
    from FL.

  6. F&J
    Joined: Apr 5, 2007
    Posts: 13,222

    F&J
    Member

    It will never run right with the outboard carbs leaking vacuum past the plates.
    ...And, the outboards do not use idle mixture screws, or an idle circuit.
    .
     
    Johnny Gee likes this.
  7. jjjmm56
    Joined: Feb 7, 2009
    Posts: 531

    jjjmm56
    Member
    from FL.

    Ok I’ll pull the carbs to check the angle of the throttle plates. I also need to check main jet size. Will turning in the idle circuit screws be enough to shut them off?


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  8. sdluck
    Joined: Sep 19, 2006
    Posts: 3,186

    sdluck
    Member

  9. alchemy
    Joined: Sep 27, 2002
    Posts: 20,407

    alchemy
    Member

    Carbs that are made for secondaries usually have a tighter plate than a main carb. Either through a different thickness, or different angle, or just a more precise fit to the bore. Maybe if you have some extra plates you can switch some out to find a better fit.

    When I've put Strombergs together I usually try different plates in each bore, and don't tighten the screws until I have a great fit and the plate is all the way closed, so I know it's centered at its best spot.

    Does Stromberg make a special shaft and plates for secondaries? Does their website give any advice on use of their carbs (new or old) as secondaries and what changes should be made to those carbs?
     
  10. s55mercury66
    Joined: Jul 6, 2009
    Posts: 4,335

    s55mercury66
    Member
    from SW Wyoming

    Also, you should be making adjustments with air cleaners on, as they will cause a richer mixture when installed.
     
  11. jjjmm56
    Joined: Feb 7, 2009
    Posts: 531

    jjjmm56
    Member
    from FL.

    So is it adviseable to run a straight linkage setup? The front and rear carbs have no idle adj screws. I’m just trying to figure the best way to get it to run. [​IMG]


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  12. jjjmm56
    Joined: Feb 7, 2009
    Posts: 531

    jjjmm56
    Member
    from FL.

  13. dana barlow
    Joined: May 30, 2006
    Posts: 5,115

    dana barlow
    Member
    from Miami Fla.
    1. Y-blocks

    " The front and rear carbs have no idle adj screws. " That's bad as far as I know,an played carbs games more then a few times. Sorry don't know about setting that up with odd end crabs. Those could be made to work prog. ,but I never did any like that. No way as far as I know ,they will work all at one time,when there is no idal screws in ends.
    But if you can fine 3 carbs,that are alike,I can give some of the things that worked for me, with 3 Ford 94s. on buddys rods.
     
  14. Petejoe
    Joined: Nov 27, 2002
    Posts: 12,264

    Petejoe
    Member
    from Zoar, Ohio

    You also need this.
    Important to mention the unisys is used on each carb with the linkage UNHOOKED, at that point sync them.
    After they are running the same then adjust EACH linkage length.
    The idle screws are only a fine tune for syncing carbs. Odds are most carbs will need a linkage length adjustment to get them close before adjusting the idle screws.
     
    dana barlow likes this.
  15. FWIW...Vintage Speed down in Vero has a bunch of parts available that might help with getting the blades to seal tightly. May be worth a look at their site. Back in the day GM had issues getting there secondaries to seal in their tri power set ups and developed (or had available) a product that you painted on to the blades and bores that sealed them after drying. Several years ago I bought this goop from Dickster to finish a tri power 348. It worked very well. Might touch base with @dickster27 down in TX or just run them all non progressive with the correct bases.
     
  16. chevyfordman
    Joined: Oct 4, 2008
    Posts: 1,354

    chevyfordman
    Member

    Your wasting your time if the outboard carbs have idle circuits, listen to these guys on here, they are telling you why you are struggling. Sorry if that is strong language. Another safety item is to get rid of that glass fuel filter in the front of your engine, its a mess if it gets broken.
     
  17. 51box
    Joined: Aug 31, 2005
    Posts: 1,099

    51box
    Member
    from MA

    If these haven’t been gone through thoroughly then it would be in your best interest to take them completely apart and make sure everything is very clean and all passages are free using air to check. Make them all the same and set them up like they were stock. If the throttle shafts have play in them, that is a vacuum leak and you will need new bushings/shafts.
    That engine will easily handle all 3 at once using straight linkage. Using progressive linkage and trying to make secondaries out of primary carbs is an uphill battle. Ive been down this road and it will never run right if the carbs are not tight and perfectly clean, matching.
     
  18. jjjmm56
    Joined: Feb 7, 2009
    Posts: 531

    jjjmm56
    Member
    from FL.

    Ok thanks everyone. So is it possible for me to block off the end carbs and just run one? I’ve been working on this for 6 yrs and would like to drive it. I hate to keep messing with the carbs when the motor isn’t broken in yet. I’m going to order the choke linkage, so then I’ll have the idle adjust screws. The carbs have been gone thru and worn parts replaced.


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  19. alchemy
    Joined: Sep 27, 2002
    Posts: 20,407

    alchemy
    Member

    "The carbs have been gone thru"

    What does this mean? On Strombergs there are many hidden orifices that need cleaning to operate properly. Did you remove the emulsion tubes to clean around them? This is absolutely necessary! And you should also blow through the J tubes to clean them as well. I think Uncle Max and Bruce Lancaster have shown tools they made to do this easily.

    And then, after they are clean, the proper combination of parts is a whole nother story. I had a pair on my flathead for about 5 years, and they ran OK, almost good. But one spring I thought they should be better, so I was fiddling with them and adjusting every which way. I finally got fed up and sent them to Uncle Max with instructions to fix whatever needed fixing. He found I had mismatched parts from a couple different series of Stromberg 97's (who knew?!). He replaced some internals, cleaned everything again, installed all new wear parts and gaskets, then test ran and adjusted them to perfection. It's not really mentioned much, but not all Stromberg 97's are the same. Yes I know there were 82's and 48's, I'm not talking about those. It is easy to take a pile of old 97's and throw together the best/cleanest parts into a carb and think it will work. That's not always gonna happen.
     
  20. alchemy
    Joined: Sep 27, 2002
    Posts: 20,407

    alchemy
    Member

    Yes you can block the outside carbs. Make some plates to sandwich above the base gaskets. Unhook the fuel supply.
     
  21. Run the center Jim ^^^^^^ done it many times. Then you can put this truck out on the road. After a few miles check those plugs to make certain you are not lean in any cyl just for kicks:rolleyes:
     
  22. Petejoe
    Joined: Nov 27, 2002
    Posts: 12,264

    Petejoe
    Member
    from Zoar, Ohio

    If you’ve been running and trying to start that engine for an extended period of time, then you’ve been flooding your crankcase oil with gas.
    You don’t want to break in or even start an engine under those conditions. Change your oil.
     
    Tim likes this.
  23. I ran Rochester carbs in a 3 carb set-up that had the end 2 carbs blocked off on my roadster. If you looked at the linkage it appeared that all 3 carbs were working, but only the middle carb was functional. I know this thread is about Strombergs, but the same principal works. You get the look of tri-power, with out the aggravation.
     
  24. jjjmm56
    Joined: Feb 7, 2009
    Posts: 531

    jjjmm56
    Member
    from FL.

    I’ve been looking at some new strombergs. What is the difference between a big 97 and other 97 carbs. Also what is different between the primary and secondary carbs. The ones I’ve been looking at seem the same.


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  25. alchemy
    Joined: Sep 27, 2002
    Posts: 20,407

    alchemy
    Member

  26. jjjmm56
    Joined: Feb 7, 2009
    Posts: 531

    jjjmm56
    Member
    from FL.

  27. Ebbsspeed
    Joined: Nov 11, 2005
    Posts: 6,250

    Ebbsspeed
    ALLIANCE MEMBER

    Optical Illusion, or are your carbs leaning forward a bit? Some manifolds have a slope on the carb mounting surface to counteract the typical angle that an engine sits in a car. If your engine is level, that would explain why the carbs are leaning forward a bit.
     
  28. jjjmm56
    Joined: Feb 7, 2009
    Posts: 531

    jjjmm56
    Member
    from FL.

    That’s just the way the pic turned out. Carb tops are level.


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  29. jjjmm56
    Joined: Feb 7, 2009
    Posts: 531

    jjjmm56
    Member
    from FL.

    How is the uni- syn from speedway? I also see that they have throttle blades for secondary carbs. I may pick up a set to check fitment.


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  30. 28 Ford PU
    Joined: Jan 9, 2015
    Posts: 464

    28 Ford PU
    Member
    from Upstate NY

    Alchemy is right.

    1. Make sure they are clean.
    2. With the throttle plates closed hold them up to a light. You want them closed tight.
    Don’t put them back on until they are tight. The reason your idle screws make no difference Is because they are not closing tight causing them to suck fuel from the main jets.
    3. Keep it simple —- run all three with idle mixture screws. I run all 3 of mine with the mixture screws turned out a 1/2 turn. Yes 1/2.
    4. Put them all back on with no linkage. Balance air flow with a unisync.
    5. Here we go again keep it simple. Tie all three to run together not progressive.


    Understanding them makes it much easier when troubleshooting. Brake it into three circuits.

    1. Idle circuit 2. Cruising circuit 3 high speed circuit.

    Start there


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