Failure was due to Briggs and Stratton weakness of a hollow cam. You must know that this engine is a Briggs and Stratton Vanguard V-Twin 23hp model 38. However basically the only stock parts in it are the block casing and the crankshaft. All the rest are basically from here:
Performance V-Twins - Monroe, NC
It is called and Eagle IV tune.
Although the rest of the parts are solid, the performance cam, which is milled from an original Briggs blank, is hollow. The Solution that Kevin Armstrong uses, is used by Precision Cams which is to hone out the center and insert a hard steel rod for strength.
If you follow his Youtube videos, you will find that this engine was to replace the 447 Rotax his plane was designed for, and has flown successfully for over two years before this failure. I have purchased the engine and all the identical parts from Performance V-Twins, including the belt redrive that he designed, but have not yet assembled mine. I now have the same cam that is prone to failure. The solution that I am going with is to replace the cast cam with a billet steel cam ordered from Precision Cams. This cam is good for 5000 rpm and 4200 - 4500rpm continuous and is much stronger than the cast cam which was designed for the stock 3600rpm.
