GM Big Block Aluminum Water Pump

[dino67]

Thanks for the info on the 3975928 water pump. I've been using it on my 67 L78 for years also. It has the 5421 stamping too. I always wondered if it was an over the counter part or a factory part. Thanks for the input.

[bergy]

I've had one of these pumps on the shelf for many years.  Must be an early one with (no date).  Question for you guys who are running these pumps - do you find that it improved cooling?

[dino67]

I never had any  over heating problems, but can't say it cools any better or worse than a cast water pump. 

[cook_dw]

No real advantages other than weight.  Cools the same in my application but I run an electric fan so....

[twol78s]

The one on my 67 L78 seems to move coolant just fine. Never had the original cast iron pump on it, so I don't have anything to compare with,  though.