Once a side cover comes loose, its hard to ever keep it tight again. When it comes loose, the crank bangs it around loosening the dowel pins. Once the pins are loose, there is nothing to keep the side cover in one spot again. The bolts cant, no matter how tight you put them. A good shoulder bolt that fits snug in the side cover bolt hole would help. Check and see if the dowel pins are loose in the block and side cover. If so, you MAY be able to make some new ones a bit bigger. If they are still tight then buy a stud kit. Get nylon lock nuts to use on the studs. Red locktite the studs in place. Buy a quality gasket. Some gaskets rip and seperate way too easy. Tighten the side cover down but not too tight. Too tight results in gasket being mushed apart. Good luck