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454+th350 strange rattle

Discussion in 'Automatic Transmission' started by northern, Nov 21, 2020.

  1. northern

    northern Junior Member

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    I have a-77 suburban with 454 mk4 and th350. Th350 has Alto Red parts, b&m shift kit, adjustable vacuum modulator, governor springs, increased line pressure, just to handle 454 torque.
    454 has long tube headers, eddy performer 2-0 and carter 750, RV cam and peanut port heads, msd HEI, nothing radical there.
    Please check out my video, there is this rattle when accelerating. There are some more videos too.

     
  2. Frankenchevy

    Frankenchevy Lying Dog-Faced Pony Soldier Supporting Member

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    Hard to hear. When I first did dual exhaust on my truck 7 years ago, the pipes were straight and long. The pipe was 1/4” from my transfer case at one point and it’d rattle against it at certain loads. That lasted about a week before I went crazy and re-did the exhaust.
     
    Ricko1966 likes this.
  3. northern

    northern Junior Member

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    Here is another video:



    It's 2wd and with 2.5" true duals and dynomax turbo mufflers, there is plenty of room for pipes.
    First I thought noise was detonation but 454 has 8 degrees of initial plus 10 degrees vacuum advance and max mechanical is 33. Tried 4 initial but noise was still there and lost a bunch of power. It has stock th350 torq converter.
    Car pulls like a freight train (these are 1/3-1/2 throttle videos, if I floor it it will melt the tires) and I'm thinking converter is ballooning and pushing flexplate against ministarter gear.
     
    Last edited: Nov 21, 2020
  4. Dmack

    Dmack Full Access Member

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    Possible loose converter bolts?
     
  5. Ricko1966

    Ricko1966 Full Access Member

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    Chasing funny rattles one of the first things I always do is bang on the bottoms of the mufflers with heal of my hand,amazing the funny noises, exhaust pipes, looses baffles, etc. Can make.
     
  6. northern

    northern Junior Member

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    Converter and flexplate bolts are tight. Also spent some time under the car hitting mufflers, headers and oil pans with rubber mallet. I did not find anything. Most of the parts are new or newish as old 350 gave up and I had rebuilt 454 in my shop so I swapped it.
     
  7. Vbb199

    Vbb199 B-rate Hillbilly Customs

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    Torque converter bolts or dust shield
     
  8. northern

    northern Junior Member

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    Bolts are tight and there is no (converter/flexplate) dust shield.
     
  9. DoubleDingo

    DoubleDingo Drain The Swamp, Completely

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    Fan hitting the shroud?
     
  10. 82sbshortbed

    82sbshortbed Get outta there! Supporting Member

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    The exhaust rattles sometimes on my SS and drives me crazy.
     
  11. jjester6000

    jjester6000 Full Access Member

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    My '74 has always made a similar noise on acceleration (even with a different engine, trans, clutch, flywheel, and exhaust it still makes it).
     
  12. northern

    northern Junior Member

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    I'll check this.
    Noise came when I was hunting some driveline vibrations and swapped old converter to one i had from old Corvette TH400. Put old TH350 converted back but did not get rid of the noise.
    I think I need to check trans cooler lines too.
     
  13. Michael Benardo

    Michael Benardo Junior Member

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    Did you buy it new that way? 454s should be paired with a Turbo 400, not a Turbo 350. The Turbo 350 is for smaller, (under 400 cubes), engines.
     
  14. QBuff02

    QBuff02 I like Big Blocks and I cannot lie Supporting Member

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    Anyone else notice or spot the correlation of the noise to the jumping of the speedometer needle in the second video? Bad cable? bad driver or gears for the speedo cable possibly? causing the cable to rattle and resonate feedback into the cab?
     
  15. northern

    northern Junior Member

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    No, I swapped 454 because original 350 had some issues.
    This th350 is rebuilt to handle 454 torque.
     

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