Since by your own words that you've had "many" failures lately; have you given thought to HOW you are installing them?
Don't drive on the "inside", rather on the edge. Driving on the "inside" will have a tendency to draw the OD smaller as it enters the hole in the block. The current issue of "Hot Rod" or "Car Craft" (don't remember which) has an article about this very subject.
Good luck!
