My 1973 4/4 sport had no slats on top and 8 extractor slats on the side. It had a fully balanced Vulcan crossflow with twin 40's, hot Kent cam and a 4 branch that glowed in the dark. Never overheated, never got wet. Still like the top slats though.
The garage left the oil filler cap off on my current +4, and oil coming onto the windscreen gave me early warning. When a piston comes up through the slats you know you've overcooked it. I am sure Morgan did not put them there for that reason !
