Hello,
Quick question on my 1993 RX-7.

I have the Greddy underdrive alternator and water pump pulleys and I'm not running the airpump any more.

Will I get enough belt contact on the water pump to keep things going smoothly?

I assume that you can't run the water pump backwards to gain more belt engagement?????

Thanks,
Brian

87 TII
93 R1

 

The underdrive pulley for the water pump, as you may have noticed,
is far bigger than the stock pulley, and so is the alternator pulley. This increase will allow for the new belt to contact properly without slipping and without need to have the air pump idling for the contact.
As for spinning the water pump backwards, bad idea! The vanes on the pump are designed to spin in one direction and will move the water in that direction only, opposite direction will only cavitate the water and cause overheating!
Art