I still have the first sears gocart with the original 4hp Tecumseh engine, that my parents bought me in 79-80 I'm now 46 years old and the engine has lasted threw me, my two sons, and now my daughter.
True enough it needs rebuilt now because it got to where is smokes a little so I pulled it off and put a 3.5hp briggs in its place, but I do still gave the engine, it still runs and even has the original spark plug in it.
I have recently bought a rebuild kit for it, and and need to get the block and head down to a machine shop.
But for an engine that is 32-33 years old, I'd say she's due for an overhaul.
Take care of your stuff as though it will be the only one you'll ever have, and just maybe it will be.