Help need new fan and have some questions

[ray_mcavoy]

Originally Posted by Navy_chief

Anyways I am needing to know what the stock fan set-up should be on the 1977 GMC SB 400 with factory air and which way rotation wise it should go I.E. Normal or reverse the engine has the long water pump also a 5 blade or 7 blade I also still have the facory fan shroud in place any help would be greatly appreciated.

Hi Navy_chief,

Dad's 77 GMC has the factory SB 400 and it has a 7-blade clutch fan. His truck doesn't have AC but it does have the large radiator that I believe was used with most all 400's and 454's.

If you're using the original V-belt setup, you'll want a normal rotation water pump, fan, and fan clutch. The reverse rotation stuff is only for the serpentine belt setups that drive the water pump pulley off the back (flat side) of the belt.