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Conrod lengths

Discussion in 'AJS & Matchless' started by mdt-son, Aug 6, 2018.

  1. mdt-son

    mdt-son

    Joined:
    Jan 19, 2012
    Hi. I am looking for 1960 on H/W single engine conrod lengths. Rods were made by WHT. Unfortunately lengths are not listed in the workshop manual or in F.W. Neil's book.

    010312 Conrod, 350/500 STD, 1950-63
    022397 Conrod, 500CS, 1956-66, 600CS, 1959-62 & 350/500 STD, 1964-66

    For 010312, I believe length is 6-7/8" (174.6mm) - does anyone have a rod to confirm this? Carillo lists a conrod of this length, thus I belive this length to be correct.

    TIA

    -Knut
     
    Last edited: Aug 6, 2018
  2. robs ss

    robs ss VIP MEMBER

    Joined:
    Aug 16, 2016
    I'm not sure what that measurement pertains to but it doesn't line up with anything on the old rods out of my '64 650ss.
    The centre to centre distance on my rods is 149.25mm (small end is 17.43mm and big end (minus shells) is 48.07mm)
    (I replaced them with a set of commando rods)
    Cheers
    Rob
     
  3. mdt-son

    mdt-son

    Joined:
    Jan 19, 2012
    Hi Rob,

    You are responding to a request in the AJS/M section. This is about genuine AMC engines, not Norton.

    Thanks for responding though.

    -Knut
     
  4. robs ss

    robs ss VIP MEMBER

    Joined:
    Aug 16, 2016
    Sorry mate - my mistake
    Gotta be more careful
     
  5. triumph2

    triumph2

    Joined:
    Aug 13, 2008
    If you are still looking for the information I can measure one tomorrow and get pretty close. It is on an assembled crankshaft.
     
  6. triumph2

    triumph2

    Joined:
    Aug 13, 2008
    I just did a quick measurement and came up with 6.897” which is.022” long but probably close enough. I’ll head back to the basement and try and get an accurate measurement.
     
  7. triumph2

    triumph2

    Joined:
    Aug 13, 2008
    Without making a complicated set up it looks like 6.875 it is.
     
  8. mdt-son

    mdt-son

    Joined:
    Jan 19, 2012
    Hi triumph2, thanks for that! I assume you measured the conrod of your '63 G80CS (022397), did you?
     
  9. triumph2

    triumph2

    Joined:
    Aug 13, 2008
    I did. It’s a very late ‘63. Possibly the last with a plunger oil pump.
     
  10. mdt-son

    mdt-son

    Joined:
    Jan 19, 2012
    I'd be interested to hear from someone with a long-stroke motor. So far I only have "less then 7in" for 010312 conrod length. Don @ Carillo thought they were of equal length (6-7/8") and maybe they are, but I'd like to have this verifiied by measurement.

    -Knut
     
  11. triumph2

    triumph2

    Joined:
    Aug 13, 2008
    No new measurement but I looked in a few books and found this in Bacon's Matchless and AJS restoration : “ The early singles had a rod with seven and three eights inch centres but for 1947 this was reduced to one of six and seven eights this remained in use for all engines with the triple row roller big end and was joined by another for ‘56........”
     
  12. batrider

    batrider

    Joined:
    Aug 9, 2008
    I have an extra '61 G3 bottom end around here. How are you measuring the rod? Are you looking for eye to eye or just the overall length? Not sure how you would accurately measure eye to eye on an assembled crank. I can take apart the cases and measure if that's the one you are looking for.
     
  13. mdt-son

    mdt-son

    Joined:
    Jan 19, 2012
    triumph2: Thank you so much for your effort. I recall having read the same passage a long time ago, now on a long-term assignment out of hometown I don't have access to my books. My understanding of Bacon's words is that both conrods - 010312 and 022397 - are in fact 6-7/8 in long, eye to eye. Having examined both by picture, I have found 022397 to have a sturdier shank and better H to eye transitions. I guess both were forged but only 022397 carries the WHT stamp and appears more wellmade. 010312 has the appearance of a "bread and butter" conrod.

    batrider: It's the eye to eye dimension which is significant in calculations and piston sizing. It would be great if you could substantiate the aforementioned length. The "cylinder" forming the big end is evident at the shoulder of the conrod. I believe it may be measured in situ using a vernier caliper, maybe a little fiddly. Divide by 2 and add dimension from top of the "cylinder" at the shoulder to the center of the small end bore (alternatively, measure to top and bottom of small end bore, add these measurements and divide by 2). The result shouldn't deviate more than a couple of mm from the accurate figure.

    -Knut
     
    Last edited: Sep 19, 2018
  14. batrider

    batrider

    Joined:
    Aug 9, 2008
    OK - I should be able to fiddle around with the measurements tomorrow. I know where it is which is half the battle.
    Russ
     
  15. batrider

    batrider

    Joined:
    Aug 9, 2008
    Hi Knut - I'm getting 6-7/8" also. (+/- .025" or so). There was a machined center on the crankpin so I measured from there to the flywheel cheek at TDC and then from the flywheel cheek to the eyeballed center of the small end. This is a 1961 G3 engine - from another Dutch Army bike.
     
  16. mdt-son

    mdt-son

    Joined:
    Jan 19, 2012
    Excellent news! Thank you so much. Another detail resolved in the Tech Spec I am preparing.

    -Knut
     
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