What RichH said times 10.
The Atomic 4 is a great auxiliary engine for most purposes. Most marinas can't or will not work on them and will charge you around $80/hour if they do. They are much more likely to tell you it is 'done' to get you to install a diesel which they will likely service as well. You can do most (if not all) of the service on this engine yourself and save a boatload of bucks in the process.
When we got our boat with A4 about 8 years ago I knew almost nothing about the engine. I have learned quite a lot since then and I am now moderately capable of doing all or most of the work it needs. The Moyer Marine forums even Don Moyer himself are great resources to help get you through any 'challenges' you might encounter.
At a minimum you should know how to replace the ignition components (spark plugs, wires, distributor, rotor etc.), change the oil, clean the carburetor, change water pump impeller etc. If I had to pay a mechanic to do these items I could not afford my boat.
Post your question over at the Moyer website for additional encouragement.
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