Wvbuzzmaster
Well-Known Member
So this is a quick question about cooling fan theory.
The car is 1972 Duster with 340 and purple camshaft, probably around 350 horsepower with a factory 22” radiator (not sure how many cores).
I have zero issues with cooling, as I have been driving it everywhere and long runs on 90 degree days. It will cool back down to the first line in the normal temperature range on the gauge after heat soaking to the middle of the normal range within 5 minutes and won’t budge off it running around at any speed, so perfect. However it has a fixed 7 blade 17” diameter (wide blade) fan in a factory shroud with 19.5” opening, about 1.25” clearance from tip to shroud. Position is about half exposed so that direction is fine. In reading, anything more than an inch of clearance to the shroud is not optimal, so the shroud is designed for 18” fan.
So my friend kept telling me to get away from the fixed fan, get a thermal clutch fan, but everyone wants about $300 for 7 blade 18” clutch fan cause “it’s hemi” and they are half right, but it’s also everything else too. So on eBay I scored an 18” thermal clutch fan of 18” diameter with 6 blades (wide blades) for $80 shipped, unknown correct for, but came off of a Mopar, I am not factory correct so seemed legit enough for me.
So will going to an 18” diameter 6 blade clutch fan be better than a 17” diameter 7 blade fan because it will fill the rad shroud better, or will it just perform as good as what I have without giving up 20 horsepower?
Bonus question, will it help to reduce belt squealing when blipping the throttle to keep it cleaned out when idling around town due to the dampening in the fan clutch reducing the load on the belt during a throttle blip?
The car is 1972 Duster with 340 and purple camshaft, probably around 350 horsepower with a factory 22” radiator (not sure how many cores).
I have zero issues with cooling, as I have been driving it everywhere and long runs on 90 degree days. It will cool back down to the first line in the normal temperature range on the gauge after heat soaking to the middle of the normal range within 5 minutes and won’t budge off it running around at any speed, so perfect. However it has a fixed 7 blade 17” diameter (wide blade) fan in a factory shroud with 19.5” opening, about 1.25” clearance from tip to shroud. Position is about half exposed so that direction is fine. In reading, anything more than an inch of clearance to the shroud is not optimal, so the shroud is designed for 18” fan.
So my friend kept telling me to get away from the fixed fan, get a thermal clutch fan, but everyone wants about $300 for 7 blade 18” clutch fan cause “it’s hemi” and they are half right, but it’s also everything else too. So on eBay I scored an 18” thermal clutch fan of 18” diameter with 6 blades (wide blades) for $80 shipped, unknown correct for, but came off of a Mopar, I am not factory correct so seemed legit enough for me.
So will going to an 18” diameter 6 blade clutch fan be better than a 17” diameter 7 blade fan because it will fill the rad shroud better, or will it just perform as good as what I have without giving up 20 horsepower?
Bonus question, will it help to reduce belt squealing when blipping the throttle to keep it cleaned out when idling around town due to the dampening in the fan clutch reducing the load on the belt during a throttle blip?
