ORIGINAL: combatpigg
What is really handy for any modeler to have is a numbered drill index. Harbor Freight has been selling them for $10. You can "sneak up" on the best pilot hole size for whatever job or material you are running threads into. It really pays to have tight pilot holes going into the plastic mounts. Make sure that the engine lugs lay on the mount nice and tight before being bolted down so the case doesn't get distorted any.
Chuck,
Wouldn't it be better in the long run to drill slightly oversized holes and just use machine screws with lock washers, nuts and threadlock?