Time for a Radiator Upgrade...?

[AuroraGirl]

Yeah that's how a flex fan works, so basically not very well, they are sharp so it's easy to cut yourself on and known for flying apart at high rpm. The thing is a clutch fan engages and disengages with heat. A flex fan flattens out as you increase rpm, so they are great at idle, usually depending on rear end bearing ok at cruise but terrible at high rpm, like going up hill or towing. We do a far bit of work on squares at the shop and I've removed a few flex fans and installed fan clutches and 5 blade fans to solve cooling issues. The reason we typically install the 5 blade fans is they are easier to get than the 7 blade.

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IM lucky the box of 78 k10 parts had a 7 blade. I used the clutch that was on the one o nthe truck over since that 7 blade has been laying face up for 20 years.

eventually new clutch

 

[84-C20]

OK @AuroraGirl If you want for fun, and I'm sure you already know the answer to this, but since you know I geek out on this stuff, in your picture the 3 blade fan has what type of fan clutch? And the 7 blade has what type of fan clutch? Bonus points if you can name the approx differences in lock up percentages?