153 or 168 tooth flywheel?

Discussion in 'High Performance Modifications' started by Wolfman911, Apr 29, 2014.

  1. Wolfman911

    Wolfman911 Member

    Oct 29, 2013
    Simpsonville, SC
    Hello all,
    I am gathering parts to build a new short block to go into my 79 Z28. I am looking to build a one piece rear seal 355 with six inch rods. I intend to buy a fully balanced Eagle rotating assembly, but I need to choose between a 153 tooth flywheel or a 168 tooth flywheel. The engine that is in the car now is a '73 block casting number and I do not know what sized flywheel it has. Are there any performance advantages between one flywheel or the other? And are there any fitment issues besides the starter? Any help would be appreciated. Thank you.
  2. TACK

    TACK Veteran Member

    Jan 2, 2012
    153=better acceleration....'68 rs z28 has what u need for manual trans..use the clutch
    And starter from the same..'68 302 3speed
    Last edited: Apr 29, 2014
  3. hhott71

    hhott71 Veteran Member Lifetime Gold Member

    Mar 30, 2001
    Joplin Mo. 64801
    Use the 168 tooth flexplate.
  4. K5JMP

    K5JMP Veteran Member Lifetime Gold Member

    so is the only difference the tooth count?
    is the flywheel diameter (not counting the ring gear) and weight the same?.. as in inertial mass?

    if so, how would you gain any performance advantage by using one over the other?

    an inquiring mind wants to know!:dumper:
  5. TACK

    TACK Veteran Member

    Jan 2, 2012
    U can get a neutrl balance flywheel..less teeth quicker acceleration
  6. K5JMP

    K5JMP Veteran Member Lifetime Gold Member

    less teeth?.. really?

    if a SBC is internally balanced, the flywheel should be neutral to begin with...

    please, tell me more...
  7. Fbird

    Fbird Veteran Member Lifetime Gold Member

    Feb 12, 2011
    atlanta, ga
    teeth vs weight = MOOT

    2 serparate issues. You can get a 40lb 153 tooth or a 40 lb 168 tooth.

    weight of the flywheel can be good or bad just depends on YOUR combination of vehicle and TORQUE curve of YOUR engine.

    Number of teeth on the flywheel is for STARTING the engine. the more teeth on the flywheel= more torque advatage for the starter motor. END
  8. K5JMP

    K5JMP Veteran Member Lifetime Gold Member

    I used to play with dirt track late models.. we used an aluminum "shaved" flywheel to get faster revs.. less inertial mass so it revs quicker.
    but you had to drastically increase the idle speed just to keep them running...

    so is a stock 153 and a 168 flywheel the same dimensions with exception of the ring gear?
  9. 70Camaro406

    70Camaro406 Veteran Member

    May 4, 2006
    Cadillac, MI
    No. The teeth are the same and spaced the same. 153 has less teeth, therefore it is smaller in diameter and lighter. That's one of the reasons that blocks have different holes for the starter, so it can be adjusted according to the size of the flywheel/flexplate.
    Last edited: Apr 30, 2014
  10. K5JMP

    K5JMP Veteran Member Lifetime Gold Member

    so how does a "dual drilled" starter work on both flywheels?

    serious question here..

    the relationship to the centerline of the crank doesn't change...

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