318/340 questions please help!!

Like most said already, the 340 had a bigger bore, lager valves that opened to bigger higher flowing ports, larger rods, floating pins [same as early 273/318], a windage tray, beefier main caps, side webbing increase in 1970.

Basically some of the things they improved [rods] or thought was an improvement were also then phased into the other small blocks. I think the lil beaker floating rods are fine for a 273/318 and the larger ones probably aren't needed, just extra weight in the rotating assembly.

as for 273/318's, the ideas with floating pins,steel cranks were already incorporated long before the 340 came a long, it's evolution baby.