ABF 2.1 build advice

Discussion in '16-valve' started by Benj31, Jul 3, 2019.

  1. Benj31 New Member

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    hi I know this has been revised before but I cannot find a thread relevant to what I need so any help would be appreciated I have recently bought a ABF from Belgium for my rally car at a apparent 230 bhp with a engine failure after stripping it down I found big end no4 had spun damaged crank and rod so I was told it was a diesel crank fitted but after checking stroke against a ABF crank I had it turns out it’s not so I want too fit one I will be using arrow 159mm Conrods and wossner pistons what adjustments need to be made to compensate for the longer stroke i can’t seem too find a build that’s not mismatched standard parts thank you in advance
     
  2. Hotgolf Forum Junkie

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    So, the diesel crank in an ABF will push a std ABF piston up an extra 1.35mm. You can use this to your advantage and machine the piston crown to suit your needs our have some custom pistons.
    The std crank will take decent rpm but if you want to liven things up gt it knife-edged to remove some weight. I can get mine down to the same weight as an 1800 crank.
    Machine the aux. shaft a little, it will give you extra clearance and also check the rod where it come close to the oil pump flange, some rods will hit.
     
    erreesse likes this.
  3. HPR

    HPR Administrator Admin

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    9A pistons have a lower compression height iirc 30.2 vs 31.6 for ABF. The piston pin
    diameter is 20 mm vs 21 mm, so would need 159/20 rods...​
     
    Last edited by a moderator: Aug 20, 2019
    erreesse likes this.
  4. Hotgolf Forum Junkie

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    Yes, the lower compression height of the 9a is offset by the extra stroke, so you deck the block and alter the piston to suit,then buy 159/20 rods available off the shelf.

    If you want to use the pistons you have you'll probably need to alter the crown depending on compression height.
    Not what the op op wants to hear but that's one way.
    A few companies in the states sell pistons to suit the crank.
     
    Last edited: Aug 28, 2019

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