granbycorvette

I have a 17" 4 blade fan. The tips run straight out. I believe it is for a 1955-56 corvette. I also have a 17 " 4 blade fan with the tips curved toward the radiator. I've noticed 1957-1960 fans have the curved tips. I assume the curved tips are an improvement. My question is are the curved tips an improvement? What is the improvement? Better airflow? Less noise? Less power consumption at high rpm? All of the above?

Easy Mike

Have you posted in C1?

granbycorvette

Thank you for prompting me to rephrase my questions in C1 forum. So far no answers in C1 or C3. I carefully measured both 1955-56 and 1957-60 blades and found the 1955-56 has a pitch of 29 degrees and the 1957 up has a pitch of 31.5 degrees. This subtle difference is not obvious until measured. Unless the flared tips somehow reduce drag, my conclusion is the 1955-56 has less drag at higher rpms and probably flows less air at low rpms. I need a fan engineer to explain the function of the flared tips. The increased pitch and flared tips were introduced at mid-year 1957 when the 265 grew to 283, so testing may have determined more airflow needed under extreme conditions with the 283, and that is why the fan was redesigned. i'm not sure if 3735314 applies to both fans. Do you have anyway to verify? The only photos I have of the FI 283 show the early fan, which makes the case that Chevy knew the early fan had less drag and used it on the high rpm FI 283. Or my photos are incorrect. I have no photos of a stock 270 hp 283, so no idea which fan came on that engine.