[Tom Vaught]

Originally Posted by lust4speed

My stamped steel impeller water pump runs as cool as the previous cast impeller pump. Both kept the engine temperature at thermostat while stuck in traffic with the A/C running on hot days - and you can't ask anything more than that.

The original water pump out of my '67 was a stamped steel impeller right from Pontiac. I'd say that would mean that Pontiac was happy with the stamped impeller's performance.

Bet in about early 1965 Pontiac did some serious Desert Testing to verify that the stamped impeller was going to do the job. Normally OEMs do at least two years of Hot Weather Testing as a sign-off process. So the original water pump probably had all of the proper contours/parts to do the job right with the new impeller.

Great info lust4speed! Did not realize the stamped impeller was offered that early, (being a 64 Guy)

Tom V.