Originally Posted by
Recycled Flyer
Hmm, I am still shy on the use of large diameter draggy props for running in purposes since they do not allow the engine to rev out freely at its most critical time, or in other words - resistance to acceleration puts strain on engine components when they are at their most abrasive time.
I don't believe I've heard of a large prop damaging a diesel while I have heard of them flying apart by over revving.
Kerosene provides good lubrication (compared to alcohol and gasoline) to wearing surfaces.
I believe the conrod lower end breaks-in during the first couple of minutes. After that you are concentrating on the piston/cylinder on an iron/steel setup. Some add a little extra castor during the first runnings.
I break-in all my 2.5cc engines on a 9x4 prop. So far, no problems. Of course...your engine, your choices.
George