ORIGINAL: Flypaper 2
There was a Willys Jeep engine back in the 50'swith the valves in the side of the block into the cyl. Didn't work very well so they weren't around long. L head and flat head are the same thing. Same as your older lawn mowers, simple and reliable.
wernt around long? hah flatheads were the standard design from the dawn of automobiles until the mid 50's. Jeep actually used them for almost 15 years.