How do you tell if a Crankshaft is offset ground rod journal?

Discussion in 'Race 400/430/455' started by CONNECTNROD, Feb 6, 2021.

  1. CONNECTNROD

    CONNECTNROD RIP Tom , miss you brother

    I have a stock stroke crankshaft that's 10 on the mains and 30 on the rods, but may be offset ground.
    Is there a identifier for that? Other then measuring stroke?
    Thanks.
     
  2. BrianTrick

    BrianTrick Brian Trick

    You really need a stock-journal crank to offset grind for a stroker. That one will have some material missing where you need it.
     
    CONNECTNROD likes this.
  3. 436'd Skylark

    436'd Skylark Sweet Fancy Moses!!!!!

    Measure the size of the rod journal.
     
    CONNECTNROD likes this.
  4. CONNECTNROD

    CONNECTNROD RIP Tom , miss you brother

    I could have asked that question better. Trying to find out if my crank has been offset ground.
    During the process, do they add material to the opposite side before grinding and end up standard size, or just remove material from one side and end up under sized?
     
  5. 436'd Skylark

    436'd Skylark Sweet Fancy Moses!!!!!

    They only remove. If it's offset it'll be ground to either the BBC or SBC size.
     
    CONNECTNROD likes this.
  6. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    No, what they do is grind it on a new center

    https://www.hotrod.com/articles/how-does-offset-grinding-increase-crankshaft-stroke/
     
    GS464 and CONNECTNROD like this.
  7. CONNECTNROD

    CONNECTNROD RIP Tom , miss you brother

    Guess its time to measure. This engine has K1 H-Beam rods and Wiesco .036 over pistons, I think it may have been to Jim Burek's shop for this work awhile back.
     
  8. 436'd Skylark

    436'd Skylark Sweet Fancy Moses!!!!!

    With wiesco pistons it's most likely a stock stroke.. here are the #s.

    Stock Buick rod- 2.25
    BBC- 2.20
    SBC 2.10

    An offset grind would be either chevy number..

    Take .030 off each per your original post. A dial caliper should be accurate enough for this measurement.
     
    CONNECTNROD likes this.
  9. Jim Weise

    Jim Weise 1000+HP

    IF you still have the last set of rod bearings that were in it, simply read the part number off the back.

    JW
     
    CONNECTNROD likes this.
  10. philbquick

    philbquick Founders Club Member

    It would take about 5 mins to know exactly what it is on a lathe.
     
    CONNECTNROD likes this.
  11. CONNECTNROD

    CONNECTNROD RIP Tom , miss you brother

    All very good info, thank you very much to all.
    I will probable do some measuring in a few weeks.
    Funny thing, I found some paperwork on this engine and the F1 rods that are in it are listed as Chevy rods. Hmm, so maybe.
     
  12. Jim Weise

    Jim Weise 1000+HP

    K1 never made a Buick rod to my knowledge, so it is very likely a BBC rod. Now, that still does not mean it is offset ground.. give me the rod length and piston compression distance, and I can tell you if it was stroked or not. I can help you determine both dimensions, if your unclear on how to measure them.

    JW
     
    Kingfish and CONNECTNROD like this.
  13. CONNECTNROD

    CONNECTNROD RIP Tom , miss you brother

    Thank you Jim, I apricate that.
     

Share This Page