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Technical Flathead engine resistance

Discussion in 'Traditional Hot Rods' started by Jellowe, Feb 10, 2021.

  1. Jellowe
    Joined: Jan 27, 2014
    Posts: 31

    Jellowe
    Member

    Here’s a question I can’t find in a book or online. What is the normal or acceptable turning resistance on a newly built, never ran 1953 flathead Ford motor on the bench with plugs removed? I realize valve springs and piston ring friction are the major contributors also lubricants. My cylinders are fairly dry, it takes about 500in/lbs to get image.jpg her turning and 400in/lbs to keep her rotating , turning by hand with my torque wrench on the crankshaft center bolt. What is normal?
     
  2. Budget36
    Joined: Nov 29, 2014
    Posts: 7,249

    Budget36
    Member

    Seems about right for an SBC. I’d think a FH would be about the same.
     
    Jellowe likes this.
  3. Bandit Billy
    Joined: Sep 16, 2014
    Posts: 7,966

    Bandit Billy
    ALLIANCE MEMBER

    Resistance is futile. Flatheads forever!
     
  4. Ziggster
    Joined: Aug 27, 2018
    Posts: 920

    Ziggster
    Member

    Seems about right. I just tried my C59A. Plugs and heads installed, but head bolts just hand tightened. I can hear the compressed air escaping on the compression strokes. Took about 40 ft-lbs.
     
    Last edited: Feb 11, 2021

  5. Hnstray
    Joined: Aug 23, 2009
    Posts: 12,171

    Hnstray
    ALLIANCE MEMBER
    from Quincy, IL

    I think 40 ft lbs would 480 inch lbs ..... very close to the 500/400 the OP posted....is it not?

    Ray
     
    alanp561 likes this.
  6. Ziggster
    Joined: Aug 27, 2018
    Posts: 920

    Ziggster
    Member

  7. Budget36
    Joined: Nov 29, 2014
    Posts: 7,249

    Budget36
    Member

    400/12. Roughly 33 ft/lbs. seems about right to me
     
    Desoto291Hemi likes this.
  8. TCATTC
    Joined: Oct 12, 2019
    Posts: 285

    TCATTC
    Member

    Those rope seals make resistance.
     
    alanp561, 34 GAZ and Desoto291Hemi like this.
  9. A5A3B975-66DE-45DB-B1D2-3B2523B98825.jpeg Pull plugs spin till oil pressure show on gauge—-replace plugs fire engine run till 180-190s fast idle 2000 rpm—-cool down —-cool down till not hot to touch —retorque heads——repeat procedure—-it gets easier every new cycle. May use an extra external fan in addition to stock fan on engine for additional cooling When breaking in a new engine.Flatheads Forever!!!
     
  10. Hnstray
    Joined: Aug 23, 2009
    Posts: 12,171

    Hnstray
    ALLIANCE MEMBER
    from Quincy, IL

    40 lbs ft would be multiplied by 12 for inch pounds, not divided. 40 x 12 = 480

    Ray
     
    alanp561 likes this.
  11. Budget36
    Joined: Nov 29, 2014
    Posts: 7,249

    Budget36
    Member

    He said inch pounds. If it were 12 in/lb it would be 1 ft/lb, right? So 400 inch/lb / 12 would be ft/lbs, or 33.33 ft/lbs.


    Edit: I see what you’re getting at.
     
  12. Hnstray
    Joined: Aug 23, 2009
    Posts: 12,171

    Hnstray
    ALLIANCE MEMBER
    from Quincy, IL

    My response was in reference to @Ziggster , converting his ft lb measure to in lb , to confirm it’s equivalency to the OP’s numbers.

    Ray
     
    ottoman, Ziggster and Budget36 like this.
  13. Jellowe
    Joined: Jan 27, 2014
    Posts: 31

    Jellowe
    Member

    Thanks for checking your motor, seems the consensus is, I'm in ok range.
     
    dirty old man and Ziggster like this.
  14. fiftiescat
    Joined: Jan 22, 2013
    Posts: 159

    fiftiescat
    ALLIANCE MEMBER
    from NY

    Fresh engines, no matter what make, are always going to be a bit on the tight side. Remember, everything is new. if the starter can turn it over, you'll be fine.
     
    Pist-n-Broke likes this.
  15. In my entire work career I can say I have never checked one. If it turned with my flywheel tool smoothly it was just fine. Final test was building oil pressure with the starter and plugs out. Never had and issue.
     

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