And if it has an aluminum flywheel, check out the two photos at http://www.krnet.org/misc/HAPI_flywheel/050917111m2.jpg and http://www.krnet.org/misc/HAPI_flywheel/050917111m.jpg . This was on Jim Hill's HAPI engine, and it appears to be a matter of seconds away from coming apart. Steve at Great Plains also has a cure for this, I believe. What made it obvious was loaded of end play on the crankshaft...the prop would move fore and aft an eighth of an inch or so, rather than the .004" or so it's supposed to be.
Mark Langford N56ML "at" hiwaay.net website at http://www.N56ML.com --------------------------------------------------------