3.1 #981 crank in a 3.4

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  • Ray Hamilton
    • Feb 2007
    • 239

    #1

    3.1 #981 crank in a 3.4

    I've been hanging on to a reground 3.1 crank to build a 3.2 from a 2.8 with but have decided to get a 3.4 PR block and use the crank in it instead. Do I need to use 3.4 rods or 3.1?
    '86 S10 Blazer 4WD, '87 2.8 with 3.1 crank and pistons, A.R.I. "Stage 2 Cam", Iron Heads with stiffer springs, Holley TBI, Manifold bored to fit the TBI Base(4.3 size), Fiero Covers, MSD Coil, DynoMax Muffler and 2.5 Tailpipe, no cat, Auburn Limited Slip, 3.73 final Drive. 700R. '85 Fiero GT 3.4 Hybrid, relieved top intake and exhaust, 57mm TB, Auto. 3.06 final drive.
  • geoffinbc
    Iron Head Enthusiast
    • Oct 2003
    • 5831

    #2
    There is no difference in the crank or rods from any 3.1L/3100 or 3.4L/3400

    The only thing that might not be exactly the same would be notches on the timing wheel or not. But if you have the notches your good to go.
    1993 EXT. CAB, 3.4L V6 TBI, 5spd manual. Sonoma
    1990 4Door, 3.2L V6 TBI, 5spd manual. 4X4. Trooper
    Because... I am, CANADIAN

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    • pocket-rocket
      Because stock sucks...
      • Oct 2003
      • 6252

      #3
      Originally posted by betterthanyou View Post
      There is no difference in the crank or rods from any 3.1L/3100 or 3.4L/3400
      And 3.4 DOHC IIRC.
      -60v6's 2nd Jon M.
      91 Black Lumina Z34-5 speed
      92 Black Lumina Z34 5 speed (getting there, slowly... follow the progress here)
      94 Red Ford Ranger 2WD-5 speed
      Originally posted by Jay Leno
      Tires are cheap clutches...

      Comment

      • Ray Hamilton
        • Feb 2007
        • 239

        #4
        Thanks for the help.
        '86 S10 Blazer 4WD, '87 2.8 with 3.1 crank and pistons, A.R.I. "Stage 2 Cam", Iron Heads with stiffer springs, Holley TBI, Manifold bored to fit the TBI Base(4.3 size), Fiero Covers, MSD Coil, DynoMax Muffler and 2.5 Tailpipe, no cat, Auburn Limited Slip, 3.73 final Drive. 700R. '85 Fiero GT 3.4 Hybrid, relieved top intake and exhaust, 57mm TB, Auto. 3.06 final drive.

        Comment

        • Superdave
          Been there, Built that.
          • Sep 2004
          • 5850

          #5
          i put a 3.1 crank in a 3400 last night, other than some slight visual differences it worked perfect.
          Past Builds;
          1991 Z24, 3500/5 Spd. 275WHP/259WTQ 13.07@108 MPH
          1989 Camaro RS, ITB-3500/700R4. 263WHP/263WTQ 13.52@99.2 MPH
          Current Project;
          1972 Nova 12.73@105.7 MPH

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