When installing a flywheel onto a engine/crankshaft I strongly recommend that you "lap the interface surface" between the flywheel and crank. The objective of this process is to insure an absolute perfect fit on the tapper.  If for any reason this is not the case you will probably NOT be able to remove the flywheel at some future date as it will be sure to friction weld the flywheel to the crank.

The process is simple enought, very similar to lapping valves into a cylinder head.  I suggest you use the fine lapping paste and not the coarse versionit is then critical that both surfaces be completely cleaned.  I personally use a spray can of brake clean and a clean rag. The final assembly tolls in addition to the obvious troque wrench to be able to reach the required 150 foot pounds of torque should also be a rather large hammer.  After first achieving the 150 ft.pds. take the large hammer and rap the flywheel bolt a number of time to insure it is tottaly seated on the cranshaft and then torque it again.

Now after doing everything right, it is still possible to have a problem.  The results can be pretty discouraging.  When all else fails a cut-off wheel and press are the only answer.