[BruceWilkie]

Originally Posted by Blackcat

I just have to wonder why it took so long? I remember going round and round with Cardone's engineers about the Impellers on the 62 Pontiac water pumps and the fact that they were sending people GMC impellers that flowed the wrong way! It took weeks of conversations and sending pumps and such to get them to change and help us. I had mentioned the fact that stamped impellers did not work as well as the cast ones and showed the ones I removed from customers overheating cars with stamped and that the replacements I put in with cast ran fine afterwords. Company's really need to listen to the community when offering replacement or re manufactured parts for cars. I wonder where my old thread about it went to?

fwiw there are about 4 different factory impellers for 4 bolt pumps 55-64 some are partial length reversed curve some are fwd curved, tall and short fin. Plus there is a reverse curve full length impeller. Each has its intended application. 4 cylinder, early 55-59 cooling scheme, and 60 up conventional cooling scheme. 55-59 Pontiac or GMC are the same pump and impeller.

Here is what I forwarded last week to GT182.

There are differences in the 4 bolt pumps used 55-63. I'll give you these links for reference to sort thru.
http://forums.performanceyears.com/f...olt+water+pump

http://forums.performanceyears.com/f...mpeller&page=2

http://forums.performanceyears.com/f...olt+water+pump POST 2 is interesting.

55-59 reverse cool scheme used the forward curved short length tall impeller. The newer ones used short length short or tall impellers curved in either direction or long length impellers with a reverse curve. Plus different wheel depths.

Look through the pics in the links.

You really need to read all the links to sort out truth from misconceptions. All impellers rotate in standard direction btw. Impeller Curvature is a design function. back curved pumps can be very efficient and less likely to cavitate at high speed.

Here is some cooling info you may want to look carefully at as well.
http://www.pontiacsafari.com/EngineCooling/index.htm Note distinct differences from early 55-59 "reverse flow" vs the 1960 "conventional"