"Same heads, cam, carb, headers, gears, vert, etc." All these thing will work different with different displacements, rod ratio's, torque, rpm etc.. so it could these part's we're just more suited to the 418.
I thought the 360 ran better for what it was than the 418.
Have upgraded from stock stroke to stroker a number of times over the years.
Have never seen just a couple of tenths. Always at least double that. So it would be very hard to convince me otherwise when I have actually done it, and raced both ways
