You were asking
Speeding up the running-in process
The thought of taking it steady for 1000 or more miles after rebuilding an engine abhors me. I don’t do this with my modern car and bikes, so why with an oldie?
Dan Sylvester, email, UK.
A number of factors are at play here, Dan. From your email details of your modern vehicles, I know both your car and motorcycles are all water-cooled, therefore run at under half the temperature of your air-cooled, iron-barrelled Triumph twin.
Therefore, the modern vehicles’ engines suffer far less expansion issues than the mid-1950s Triumph.
Materials employed and machining tolerances/ techniques have progressed by light years from the 1950s and when we rebuild an older engine with period or replica pistons, bored and honed to original tolerances and the same applies, albeit to a lesser extent, to bearings, we are playing the period, not modern, game and appropriate running in is essential.
In your emails you made the valid point that racers of the period wouldn’t have run their engines in for hundreds of miles. I don’t know what road racers did, but when I was spannering for a friend who ran Greeves and Villiers Starmaker engines as a scrambler, our running in procedure was
