I just had an interesting chat with Mike at Waterpumpman when he returned my call. He was really surprised that I am interested in a cast impeller and said that he generally throws them away when they come in and uses stamped for his rebuilds because they are cheap and he believes they work good. I told him that it is my understanding that many Pontiac guys have proven that a cast impeller with tall veins and a properly fitted divider plate results in lower engine temp's. He told me that he can give me whatever I want so if I want a cast impeller with tall veins it's no problem... but, he did say that the tall veins are prone to bits breaking off so he wanted to warn me about that.
Unfortunately I have an early 69 short pump so he doesn't have a core but as long as I don't need an original I can give him any short casting and he'll rebuild it with a cast impeller.
Mark
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