Finding a parts catalog for a certain engine can be time consuming, if you don't know how to use the Search Engine.  As an example, let's say you have a Lycoming HO-360-B1B.  Enter B1B in the search box in the upper right side of the page and left mouse click the Search link.  If you don't see your catalog, check the Search in product descriptions and left mouse click the Search link.  If you put 360 B1B it will not return any results, because it has to match exactly.  PA-24 would find the service and parts manuals for this airplane.  If you need help email us and we will help you find the manuals you need.