New aluminum fan blade problem

[rivcokid]

Hi all - I waited at least 6 months for the new aluminum fan blades to appear. I got mine and we just went out this morning to put on in my 31 roadster. Guess what? It doesn't fit. We put the new blade on the water pump housing (sealed bearings so a leakless one) and couldn't get it on far enough. Took out the calipers and the ID on the original steel fan blade is 1.79 inches, whereas the new aluminum one measures 1.68. There's also about the same difference depth wise too. In short, the castle nut will go on but barely, we can't get a cotter pin in, and when we do tighten the castle nut, the entire pump and fan blade will not move. Naturally, this happened Saturday morning of a 3-day weekend, so calling Snyders is out until Tuesday.

Has anyone else run into this? I'm wondering if the fan blade housing has to be thicker due to the nature of aluminum. BTW - I have no way of machining this thing myself.

Thanks for any ideas as usual!