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Thread: Acceleration hesitation, baffled.

  1. #1
    Join Date
    Mar 2013
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    Central Calif.
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    Default Acceleration hesitation, baffled.

    As much as I hate to ask for input sometimes a person can't see the forest for the trees.
    I will, instead of listing everything I've done, give the known since.
    69, 74" stock bore, s&so barrels, kb 9.0:1 pistons.
    Andrews b2 camshaft, s&s super e, andrews 4.8 ohm coil, stock timer, auto. Recent rebuild. Compression at 115 and 120, seems low, could be cam.
    Issue, starts, runs, sounds great. Around town great, no hickuPS, backfiring, sputtering, restarts great, throttle up at idle great.
    When at speed shifting from 2-3 rpm climbs normal, if I let rpm reach shifting point and hard accelerate it hesitates, won't throttle past, holds its speed. If I am at the low end of 3rd gear and throttle hard it hesitates for a second and blows by it to reach 65mph , same in 4th, at steady speed feels great, try to steadily accelerate past 60 mph no go, slow down to 3rd gear and blast it to 65 then shift and try to maintain, it hesitates again.
    I've tried a ton of things will answer if I get any takers/help on issue..thnx

  2. #2
    Join Date
    Jun 2001
    Location
    Central Illinois, USA
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    Default

    PoorBiker!

    First diagnostic: Did you thoroughly bubble-test your manifold assembly with a regulated air supply?
    (Beware that S&S manifolds can have casting porosities nearly anywhere...)

    Beware also of common stainless clamps that are ~.030" wider than the proper 3/4", and can give grief on a Shovel or Sport.

    Good luck!

    ....Cotten
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    AMCA #776
    Dumpster Diver's Motto: Seek,... and Ye Shall Find!

  3. #3
    Join Date
    Mar 2013
    Location
    Central Calif.
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    Default

    Quote Originally Posted by T. Cotten View Post
    PoorBiker!

    First diagnostic: Did you thoroughly bubble-test your manifold assembly with a regulated air supply?
    (Beware that S&S manifolds can have casting porosities nearly anywhere...)

    Beware also of common stainless clamps that are ~.030" wider than the proper 3/4", and can give grief on a Shovel or Sport.

    Good luck!

    ....Cotten
    Hey Cotten,
    Yes sir, learned my lesson from linkerts...made a block off plate and tested at 10 psi cold motor, then hot motor at a little higher psi...no bubbles anywhere.....

  4. #4
    Join Date
    Jun 2001
    Location
    Central Illinois, USA
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    Default

    Well Poorbiker,

    I have no experience with S&S diseases.

    (Hot motors are hard to work around, getting the carb off and all quickly for a test, so I just go straight to 15 psi cold.)

    So picking at straws: Are you running "solids" with aluminum pushrods? If so, are they adjusted to a 'pretty-tight' spin,.. cold?

    ....Cotten
    AMCA #776
    Dumpster Diver's Motto: Seek,... and Ye Shall Find!

  5. #5
    Join Date
    Mar 2013
    Location
    Central Calif.
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    Default

    S&S diseases are bad but don't know what else to run.
    I see a company making an adapter for cv's, press on with jb weld.
    Chrome moly pushrods, hydraulic, adjusted properly..and then double checked...
    It's the odd hesitation and no rpm gain when accelerating from a steady speed that's odd...
    I will note here that I took the same carb off my chopper which runs flawless and problem remained the same....

  6. #6
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    Mar 2013
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    Was thinking about solids but you really should have a cam designed for running solids, I know guys convert their lifters but not comfortable with that..

  7. #7
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    Poorbiker!

    I was only warning against aluminum pushrods themselves; "solids" work, unless that new-fangled Andrews cam specs for hydraulics. (Andrews left my zodiac decades ago...) Even with solids, any pushrods but aluminum should be 'friendly'. Aluminum would work, if adjusted to the minimum.

    Throwing another carb and manifold at it is throwing money at it. (And JBWeld isn't as gas resistant as it used to be....)
    There are no bad carbs, if everything is in order.

    Good luck!

    ....Cotten
    Last edited by T. Cotten; 05-04-2017 at 04:21 PM.
    AMCA #776
    Dumpster Diver's Motto: Seek,... and Ye Shall Find!

  8. #8
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    I'm a leineweber Guy personally, I just got this cam in a trade, it has sketchy specs but as I said it was cheap, sometimes cheap bites you in the ass, lol...thnx...

  9. #9
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    Also I have had no trouble with my linkert once I got the air leaks resolved, over a year of nearly riding everyday..
    While talking about linkerts do you use an adhesive on your float screw to prevent vibration loosening it, if so what? Thnx

  10. #10
    Join Date
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    Poorbiker!

    I use an isocyanate urethane industrial coating that isn't available 'off-the-shelf'.
    But "Seal-All" survived my P4gas immersion tests last year; Hope it does this year, too.

    And if the screw is firmly tightened upon the pivotnut, it shouldn't come loose, but a compressible float, be it cork or foam, can come loose on the pivotnut.
    So the adhesive was really to secure the float to the lever, not to lock the screw.

    (I cut my floats to a 'squeak' fit to my pivotnuts, and also aim at some compression of the float by the lever to secure it. But an adhesive is added assurance, of course.)

    ....Cotten
    PS: Attached is an OEM float that shows that the adhesive bridged beyond the screw to secure the two 'ears' of the float that extended above the floatlever.
    (Naturally, this adhesive suffered from time and fuel, even though the original celluloid coating survived!)
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    Last edited by T. Cotten; 05-04-2017 at 06:20 PM.
    AMCA #776
    Dumpster Diver's Motto: Seek,... and Ye Shall Find!

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