[Singleton]

Originally Posted by 68WarDog

Why would anyone want to underdrive the waterpump and alternator?

Typically, Pontiac had their non-A/C engines underdriven by 8 to 15%.(water pump driven at 85-92% of crank speed).

The CVF pullies I have on my non-A/C GTO are both 6.2", (crank and WP), for a 1:1 ratio, (or 100%). The High-flow that CVF offers is the same 6.2 wp pulley with a 8" crank, for a 129% overdrive. I'm going to try a 8" wp pulley to underdrive it to 77.5% of crank speed. My engine idles at 1000, (manual trans), so the water pump will still be turning at 775 rpm. I run a flex fan with no cooling issues, but I don't like the fact that the fan is turning 6000 rpm at my shift points. By underdriving it 77.5%, at my 6000 rpm shift point, the fan will now be turning only 4650 rpm. Less stress on the fan blades and less drag.

[68WarDog]

[QUOTE=Singleton;6348546]Typically, Pontiac had their non-A/C engines underdriven by 8 to 15%.(water pump driven at 85-92% of crank speed).

Agreed, however Pontiac engineers weren't dealing with todays higher hp applications and performance standards. Also today's fuels don't provide the cooling and lubrication affect of the 60s and 70s.