For a 1970 350 how many blades should the fan have and is a clutch used, if so thermal or non-thermal? Thank you.
My 71 skylark has a 350 4 barrel carb and AC; it came equipped with a 7 blade thermal clutch fan. Your normal driving circumstances and geo location may drive needs due to load temperatures . The fan clutch should give you a little better fuel economy also as it will free wheel at higher speed and air flow. Hopefully someone else will confirm same requirements for the 70 year.
If you have AC, a thermal clutch was normally used. My 71 GS with AC has a 7 blade thermal clutch. Stay away from flex fans and direct drive fans with fixed blades. Flex fans decapitate stuff and are deadly. Fixed blades, even OEM type, are loud and kill horsepower. Thermal clutch is the way to go
Thanks for the replies. I have acquired a seven blade fan and new thermal clutch. Just had a thought, are the radiators the same on 350 AC and non AC cars? Also any know the length of bolt needed to attach fan to water pump. Can't use old bolts, there was a spacer on the fan.
The radiators would be the same as far as fit. There might be a difference in the number of rows, maybe. The clutch mounts to the pulley and water pump flange with short studs, and nuts. They are like carburetor studs, course thread on one end, fine thread on the other. I believe they are 5/16 threads. Here is one source, https://www.amazon.com/Edelbrock-80...ywords=carburetor+studs&qid=1628862051&sr=8-1 The lock washers aren't needed. ToddsGS has these. He probably has the nuts as well. https://www.stage1restoration.com/product/clutch-fan-studs/ The nuts you can pick up in any hardware store.
