Crank re-grind

Discussion in 'Mech Tech' started by Deefer66, Oct 23, 2019.

  1. Starting with a fresh case and crank (Type 4 2ltr) on bore for bearing 70.00-70.02 you have a crank journal of 59.97 =59.99 (No.4 can be 0.01bigger ! So 39.98-40.00) and connecting rods at 49.98-50.00
    So a case which measues as new and a crank that needs a fettle.and if I've got .25 extra on bearings I'm asking for journals at 59.72 - 59.74 ? (No.4 @ 39.73-39.75) And connecting journals at 49.73 -49.75 ? Or do I just say top number?

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    Last edited: Oct 23, 2019
  2. If you have sourced .25 oversized bearings you just need to go for the first grind on the crank. Give the machine shop the std journal sizes from Bentley & ask for a .25 grind.
    I know some type 4 main bearings sizes are difficult to get hold of now, I would buy the bearings first :thumbsup:
     
    snotty likes this.
  3. Got them.. put them in the box with the crank in case they want a measure.... didn't know if you said .25 they'd just take that off! I'll find a way to get Bentley printed from my tablet

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  4. If they’re any good, they’ll check everything first. As above, copy the relevant pages from Bentley. They’ll know what to do (hopefully).
     
  5. Thanks ..
    crank packed with spec, heads packed with new valves, rods packed with new bushes and a gudgeon pin .. all dropped off at machine shop.... here's hoping!..

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  6. mikedjames

    mikedjames Supporter

    We welded the valves so they wouldnt fall out; and welded a couple of the rods to the pin to make a support for the art project we thought you had asked for.
    We sawed the crank and welded it with all the throws on the same side. It seemed neater.

    The new artwork is called " over 25 and cranky."
     
    Deefer66 likes this.
  7. Spare bits might go this route when welder comes back from repair shop.. if eBay sales don't work..

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  8. MorkC68

    MorkC68 Administrator

    Before you get too far down the line, check what bearings are available and in stock for the grind dimensions you would like.

    I know when my original plan of a 2258 type 4 build was in the research stages, some bearings had become unavailable and had no restock dates.

    Just a thought for you!
     
    snotty likes this.
  9. Cheers..its ok. bearings in the bag! mains and big end..

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  10. MorkC68

    MorkC68 Administrator

    excellent! :D

    As you where!
     

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