[Land-speed] BBC Firing order

[Kirkwood]

Well, if you think of the crank as a long torsion bar with a load at one
end, what have you accomplished? As John points out, the crank does twist.
So with a 5-7 you apply a twisting force close to the reactive load. With
the 4-2 you have moved the twisting force farther away from the load. The
longer the torsion bar, the less stiffness. You are imparting more twist,
not less twist, in a 4-2 set-up. But maybe that is the purpose.  Skip, if
you have individual port injection; how can there be interference from
either firing order?

 

I have been reading about this controversy ever since marketing created the
idea to sell more cams. Regardless of the magazine article, I have never
seen an honest, factual engineering study with good data.

 

The altered firing order cam would trade 5-7 interference for 4-2 

interference  wouldn't it ? Maybe it would reduce crankshaft harmonics by 

eliminating the normal 7,2 sequence crank twisting .   -John