http://www.ntnoa.org/enginebreakin.htmhas some good advice
there is still some controversy over running hard(methodically) and taking it easy on the initial run on the motor for seating the rings. one point against is modern machining practices and tolerances dont leave much material that has to be removed to seat the rings. im 5k into my rebuild, used a 268 cam with the OS valves and an EB engine kit for mine. ran it at 2500 rpm for about 15 min(AFTER warming it up), allowed it to cool overnight because it was midnight and my wife was quite angry at this point.<img src="/forums/images/graemlins/rolleyes.gif" alt="" /> next day i changed the oil(used 30wt for the first pass) then did it again. this is to break in the cam first. i believe i used 30wt for the first 1000 miles as well. no syn, just reg oil. i took her out and in 2nd and 3rd gear ran it at full throttle from 2000 to about 4000 rpm and allowed engine compression to slow it down to 2000 again. did this about 4-5 times, then drove it easy for the next 3000 miles, varying speed and not taking it over 55mph, which wasnt too hard for my 6 mile daily commute. after the initial cam-pass oil change and the next one at 1000, i went to the normal 3k change, and after 3k ive started to run syn oil, no probs at all. the biggest thing is in these first couple runs, let it warm up completely first! no matter the vehicle or the miles, i never drive it hard until its completely warmed up. just my 2 cents, hope it helps
