Most Delco alternators that I am familiar with have separate fans, the fan is just pinched between the pulley and bearing spacer. The only problem that I have heard is that with the larger pulley the alternator wont charge at low engine rpm. Okay for a drag racer but not very good for a street driven car.

Paul

After doing some more research the march150 (last pic) might be a better compromise.

gets my ratio closer to the corvettes and z28 from the early 70s

my car does a lot of highway cruising with 3.42 rear gear

the 1.75 ratio should be ok

fairly minimal electrical draw on this car

7 inch crank pulley 3 inch one piece alternator fan/pulley 2.33 stock ratio now

7 inch crank pulley (new 4 inch pulley) 1.75 ratio

i realize this search for half a horsepower is perhaps silly to most

im having a blast finding it