SB/BB cooling fan interchangeability?

[miketyler]

I am considering upgrading my stock 7 blade fixed fan on my 340 to a BB fan with clutch. Are the hub hole patterns the same? The BB fans are a larger diameter and have a greater pitch (so I'm told). Has anyone tried this and realized a noticeable improvement? I would probably have to trim my shroud for the larger diameter and was considering spacing the radiator closer to the fan so I could put a high CFM SPAL pusher up front for aux cooling when I need it. 

[Chryco Psycho]

the clutch is the same bolt pattern , there were a # of different fan sizes you probably need a 17 or 18 " the C bodys were larger at 19-20 " , Flexalite has a 6 blade fan 18" that will bolt on

[miketyler]

There really isnt much wrong with my current setup - I was only considering this if there is a benefit of more flow via a larger diameter or higher pitched fan or gas savings from running a clutch. Is the flexalite fan higher pitched or a better solution than stock? 

[Chryco Psycho]

it is similar to stock , the cluch will save you $$ & power though as it will free wheel when it is not hot enough to need it