Cooling fan and clutch question?

[Pacecarjeff]

I have seen that all of the early Chevrolets used the short water Pump through 1968 (except Corvette = through 1972) With this pump was I thought Always used a fan with 3" bolt spacing. Now I find out from some people that the 67-8 Z/28, as well as the L-78 used the later 3.25" spacing.??  is this true?

I had thought that spacing was not used on Chevrolet motors untill 1969.

3.25"  is the spacing used for the later "long" water pumps.
Are the water pumps different on those 2 - 67-8 Chevy applications, as to use a differnt fan and clutch.

I know that all the other motor divisions used the larger spacing, and Chevy was different. Why were these 2 applications different then the rest of the Chevrolet engine line?

[lakeholme]

First, take a look at this:
http://www.camaros.org/coolingsystems.shtml
I realize this only addresses part of your question...
I think Kurt can help you with the rest.  He straightened me out on the 3 vs 3.25 spacing a while back.

I went back and found that thread.  Take a look:
http://www.camaros.org/forum/index.php?topic=482.msg2790#msg2790

[Pacecarjeff]

Thank you - That is very helpfull information.
I learned something new, never realized that Chevy used the 3.25 spacing before 1969.