Lycoming doesn't make a maintenance manual for your engine. They published the Lycoming Direct Drive Overhaul Manual which includes your engine. There's also SSP 1776 that has the metrics and there's also a parts catalog. Lycoming does publish an owner's manual for your engine. But, truth be told - you should really know what you're doing when you go into your engine - or have someone there to guide you. There's nothing worse than killing your family, friend's son or people on the ground because you really didn't know what you were doing when you tore into your engine like it was for your lawn mower. Then there's AD, SB, MSBs for your engine then there's manuals for your accessories just as complex as your engine. Some you have to pay for, some you can find for free. You just have to search. Oh, yea - they publish updates for everything too so you have to be careful as to what version you get. Also there's AC 43.13-1b and the whole AC series. You can also search 14 CFR for stuff that covers your engine too like how to do a compression check, clean plugs, inspect stuff and so forth. Don't worry - some smart engineer with years of experience and education, a PE license, insurance, peer review process, etc etc etc wrote the stuff that's FAA approved or accepted - if it's made there's PMA approval, STC's too - don't forget that stuff.
But truth be told - the aviation industry is filled with people too lazy to read, failed to pay attention to their instructors, barely passed their classes, have no interest in aviation, think they're smarter than they actually are, will tell you "that doesn't matter" when you tell them they're not doing it as the book instructs (because they never read the book), they barely made it out of high school where they took shop and as many P.E.s as they could. They're poor, foolish, have low IQ's, and are just plain lazy. So maybe you're better off doing things yourself.
Good Luck