End float is the curse of type 1 engines. In theory you can adjust end float by using appropriate thicknesses of the three shims between the flywheel and crank but, in practice, this seldom works. Most end float, especially if it is more than a quarter of a millimetre, means the case has been hammered out and the engine needs to be rebuilt. Line boring is the usual way of making a case reusable, but I think most cases in circulation have been line bored too many times and they should be scrapped. I personally won't trust any line bore more than .25mm. In my experience, rebuilt engines where the cases have been line bored beyond .5mm won't last more than 25,000km before catastrophic failure.
However, IMPI assures me that the issue is not the size of the line bore (some engine builders will bore a case up to 3mm!), but whether it is straight. Most line borers are drill mounted and not capable of boring true. They will also not bore true if the line borer is even slightly dull.
Volkspares sells brand new type 1 engine cases for about R5k if you want to build a truly reliable or high-performance engine.
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