The reason for the Swap is that it elimanates # 7 cyls. trying to fill its
intake runner from the same area of the plenum imediately after # 5. By
swapping 4 and 7 it eliminates this-- another side benefits is # 7 runs cooler
for it is not as lean..
Notice in the firing order below ---if 4-7 were swapped-- no two cyls fill
adjacent to one another in sequence
>
>
>
> My freinds that run mountain motor pro-stock's do some wierd stuff with
> firing orders... I can't remember the sequence but it's not GM...18436572.
>
> K
> ----- Original Message -----
> From: <richk@mercurylink.net>
> To: <land-speed@autox.team.net>
> Sent: Friday, March 12, 2004 7:04 PM
> Subject: 4-7 firing order cam swap
>
>
> > Twice I've run across this in the past month but haven't seen any
> > technical discussion on the subject. Swapping chevy firing order giving
> > claimed increase of 3 - 20 HP in a simple A - B cam comparison. What's
> > being gained here? How does exhaust or intake design affect this?
"Sparky"
Lakester 2211
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