1OHV means OverHead Valve - an engine design where the camshaft is installed
inside the engine block and valves are operated through lifters, pushrods
and rocker arms (an OHV engine also known as "Pushrod" engine). Although an
OHV design is a bit outdated, it has been successfully used for decades. An
OHV engine is very simple, has more compact size and proven to be durable.
Downsides: it's difficult to precisely control the valve timing at high rpm
due to higher inertia caused by larger amount o