Techtips

Techtips

If you’ve ever taken apart an engine, or at least stripped the outer covers off of one, you’ve probably faced this reassembly dilemma: Which case screws go where? On most engines, the screws securing any given case or cover are of varying lengths. Some differ only very slightly, but if you use one that is too short, you could pull the first few threads out of the hole; and if the screw is too long, it could bottom out before pulling the cover snugly against its mating surface.

Usually, you can solve this puzzle by randomly inserting a screw into each hole (don’t thread them in) and observing how far each one projects above the surface. When ail of the screws are the same distance from the case (usually somewhere around 3/8to 1/2-inch), it’s then safe to thread them in and tighten them.

But there’s an easier way, using a technique that’s as old as the hills. With a Magic Marker or a Sharpie, draw a simple outline of the case or cover on a piece of cardboard. Mark the location of all the case screws with a round dot that’s about as big as the head of one of the screws, and use a punch or an awl to poke a small hole through the cardboard at each dot. Then, as you remove each screw, push it through its representative hole in the cardboard. Not only will you then know exactly where each screw belongs during reassembly, but the cardboard serves as a good means of keeping all that particular case’s or cover’s screws together until they’re needed.

-,Paul Dean