I've finally got my engine back in again with new barrels and pistons and new cylinder heads installed (and thermostat working after some jiggery pokery). What should my break in procedure be? I've had a look at this http://www.aircooled.net/vw-engine-break-in-procedure/ which is helpful and I have the Tom Wilson book which describes the same procedure but with a bit more detail about the loading of the engine while driving (20-45mph acceleration followed by coasting back to 20mph - 5 times). Only thing is do I need to do the 20 mins at 2000rpm? I didn't touch the bottom end and this seems to be about breaking that lot in. Or can I go straight to the acceleration and coasting break in to seat my piston rings?
The 20 mins at 2000rpm is to break in the cam. You haven’t replaced the cam so go straight to the ring break in procedure.
