Well it has to be 18736542 the piston would not be at top dead center with 18476532. My problem is I don't know enough about too many things, the older I get the less I seem to know. I've checked everywhere and read a few hundred different opinions on what is the advantage or disadvantage of the swap and why. Intake, exhaust, smoothness, lope, everyone has an opinion and none the same. I finally found a Dec. 11th, 2006 article from Hot Rod magazine. Lunati gave them a 7-4 swapped cam to try on a big block. They have a bit of info that satisfied some of my curiosity about the switch.
Seems the early Fords have the same firing order as our Pontiacs and Chevs, if you renumber the cylinders with #1 on the left instead of the right. The later 351s and 5.0L Fords and the Chevy gen III and IV LS engines have the 18736542 firing order.
According to the crank and valve train guys at GM the swap beginning with the gen III was not made for smoothness or power gain or any of the other reasons tossed around but to even out main bearing load. Seems they had no problem with the earlier cranks but with the new engines the # four main had significantly higher peak firing loads than number two main. They swapped the firing order to even them out.
It's an interesting article with input from a lot of top race and engine people.
