I have a 272 in my '55. The builder of the car installed a Saginaw PS pump, alternator, and AC compressor on a 3-sheave crank pulley. The concern I have is the AC compressor drives off the fan/water pump pulley. Considering the belt tension needed on the compressor, is it putting too much side pressure on the water pump bearings and seal? I've considered moving the compressor belt to one of the other grooves on the pulley but it presents alignment challenges I'd prefer not to undertake if the water pump can handle the tension. Anybody have any experience with this set up that can give an idea of water pump life?

I've been running the crank/water pump/alternator/ac compressor on one belt for a couple years now. I was concerned about slippage, but it hasn't been a problem. The car has EFI, and electric fans and runs a 90 amp alternator. When everything is on including headlights, that loads probably as big as the a/c is.

The pump's several years old, it's one of Pegleg's aluminum ones and might have a little better bearing.

miker
55 bird, 32 cabrio F code
Kent, WA
Tucson, AZ

Miker, is this a serpentine belt or V-belt?

V-belt. Alternator low in the generator position, compressor above it. Saginaw pump in the original pump location, on the second belt.

miker
55 bird, 32 cabrio F code
Kent, WA
Tucson, AZ

If you are running a double groove fan pulley the PS pump on the opposite side it helps by pulling against the compressor/alternator pressure. My compressor is below the alternator so the belt pressure is pulling down and to the passenger side from the fan pulley. My alternator and PS pump are each by themselves on a separate pulley on the crank. I just think it is better to have the AC pulling on a crank pulley. It is what it is, I guess I'll wait to see if it causes any water pump problems. Thanks for your reply. 

I'm running a single grove w/p pulley, so the compressor and alternator are on the passenger side. The p/s pump runs only off the crank pulley. No fan load, it's electric.

miker
55 bird, 32 cabrio F code
Kent, WA
Tucson, AZ

I gotcha'.  Looks like we are in similar situations. maybe the pump bearings can handle it. Thanks for clearing it up.
Gene