[Jack21]

March makes two pulley ratio setups. High Performance, and Street Rod. For some reason, they don't make a big deal out of the Street Rod ratio, you have to ask about it. The HP ratio uses a larger diameter water pump pulley and underdrives the water pump. Good for reducing high RPM water pump parasitic HP loss, but not so good for low RPM cruise flow. The Street Rod ratio uses a smaller diameter water pump pulley (same crank pulley) that runs the water pump faster, and pushes more water through the engine at low RPM. Great for keeping engine cool at street RPM. Another help is an aftermarket, rather than OEM Ford high volume water pump.

The pulleys are about $50 or $60. Get one of each. One for the street, one for the track.