Hello, I have been lurking for a while, I have found tons of useful info here on this site, but I have a question I just can't get figgured out on my own. I have a old parts tractor made in the early 90's, I don't know what make other than it was green and had rear steering. but anyway the tractor is very clearly labeled 16HP, as is the engine cover. The engine is a horizontally opposed 42a707 which my research tells me that the 42a707 is a 42cu in engine, as far as I can tell 42 inch motors are 18HP. but my engine cover very clearly says 16hp on both sides.
was this common? if I take a head off and measure the bore what if it is actually a 42cu in motor? is it 18 or 16 HP? does it matter?