
One noticeable thing about the original SBC firing order is that it not only has most names in the list, it also has all the most performance oriented names in its list. I have never seen a credible explanation as to how this helps anything other than cam makers profits. The charging robbing effect is identical except for being relocated from 5/7 to 2/4.Ĭylinders 5/7 and 2/4 both have the intake ports grouped as pairs with only a divider wall between the ports so it does not alter the geometry of the 90 deg in firing order separated ports.

The Chevy 4/7 swap simply moves the 90 deg sequence adjacent pairs to another position.
