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AD or AF engine for Splitty?

Discussion in 'Engine & Transmission' started by mamv, Jun 23, 2019.

  1. mamv

    mamv Member

    Messages:
    38
    Location:
    Adelaide Hills
    Hi All,

    Just bought two long motors as a job lot suitable for a rebuild for my Splitty.

    AD motor (50HP) had a leaking oil cooler when removed
    85.45mm pistons.

    AF motor (46HP) had a leaking front main seal when removed.
    approx. 87mm pistons.

    Is the stroke different between the two? They appear the same 69mm. What might give one more HP than the other since the AD has the higher HP but smaller diameter pistons? Could it have been the carby?

    Which is best for a kombi considering torque?

    Any recommendation welcome
    Cheers Andre
     
  2. syncro

    syncro Well-Known Member

    Messages:
    9,325
    Location:
    Southern Highlands
    AF is a newer version. Both would have originally had the same size pistons and crank but the AF may have had more emission controls. The only original part may be the case.
     
  3. Barry

    Barry Well-Known Member

    Messages:
    3,661
    Location:
    Abbotsford NSW
    85.5 pistons are stock 1600cc

    87 pistons are aftermarket slip in 1641cc - unless some one has gone the machine in 87’s. Possible - but unlikely.
    Need to measure cylinder wall thickness.

    Both “should” have a 69 crank.
    Again have to measure to get truth.

    HP will come down to compression ratio, cam, head work and carbs

    Check for end play.

    You should get both cases checked my a machinist to see which is better suited.
    One may have been machine cut several times already and therefore not suitable
     
    Wayne murray and David H like this.
  4. mamv

    mamv Member

    Messages:
    38
    Location:
    Adelaide Hills
    Excellent info thank you.
    Yes both are 69mm stroke. the AD has larger head stud diameter.
    I'd like to try and hunt down the specs of each re: cam, carby and compression.
    Does anyone have a good link to specs for these engines?
    Also, did kombi 1600's have a different cam to beetles?

    Cheers
    Andre
     
  5. Barry

    Barry Well-Known Member

    Messages:
    3,661
    Location:
    Abbotsford NSW
    Earlier cases had 10mm head studs inserted directly into the case.
    VW changed to 8mm studs with inserts around 1971-ish.
    The 10mm had expansion issues and resulted in pulled head studs.
    If you are doing a proper rebuild you should be putting case savers in and 8mm studs
     
    David H likes this.
  6. Barry

    Barry Well-Known Member

    Messages:
    3,661
    Location:
    Abbotsford NSW
  7. mamv

    mamv Member

    Messages:
    38
    Location:
    Adelaide Hills
    Wow, that's fantastic info. Just what need Thanks
     

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