Author Topic: Fan and Shroud  (Read 529 times)

Offline stu in wichita

  • Jr. Member
  • **
  • Posts: 51
Fan and Shroud
« on: August 12, 2020 - 12:08:27 PM »
Not sure if this is where to post this but did not see a board for cooling system.

I've got about 400 miles on my '74 Challenger and all seems pretty good.  On a 90 degree day, the temp creeps up when not moving.  It doesn't overheat, but it gets over 100 here an I heave A/C, so it will get worse.  I assume that the problem is inadequate air flow so I bought a factory style shroud.  Problem is, the fan is too large to go inside it.

Here's what I have:
   - 318 2bbl auto, all stock
   - 26" Champion radiator
   - OER fan shroud.  Looks like factory shroud and fits Champion rad mounts perfectly.  Opening measures 20"
   - 5-blade metal flex fan, 20".  I thought it was stock but not sure.

Alignment with the center of the fan looks like it will be fine, except that the fan is tilted noticeably to the radiator, as if the engine is too low in the back.  That may be typical but I don't know.

I think all I need is a different fan, but I'm not sure what works best at a decent price.   Any help or suggestions will be greatly appreciated.

-Stu




Offline 70chall440

  • Sr. Resident
  • ******
  • Posts: 6184
Re: Fan and Shroud
« Reply #1 on: August 12, 2020 - 07:01:58 PM »
You have a number of issues going on here. First off, you need to determine if you have a heating problem or not. Do not rely on the gauge in the dash, you really need to have a quality manual gauge and a hand held IR thermometer.

As to your fan, I don't know which one it is but so long as you have a shroud you should be ok but perhaps you need a different fan; Mopar made a lot of different ones not to mention the aftermarket.
Current Mopar
70 Challenger RT 440-6 EFI, 73 Cuda 416-6 EFI
05 Hemi Durango, 01 Ram 4x4, 14 Ram 2500 4X4, 10 PCP Challenger 6 spd RT, 01 Viper GTS ACR, 52 B3B w/330 Desoto Hemi, 70 Hemi RR (under const)
Past Mopars
9 x Challengers. AAR Cuda, 4 RR, 2 GTX, 4 Chargers, etc... (too many to list)

Offline stu in wichita

  • Jr. Member
  • **
  • Posts: 51
Re: Fan and Shroud
« Reply #2 on: August 12, 2020 - 09:21:58 PM »
Thanks for your input.  It's definitely not overheating - checked with both external gauge and infrared handheld.   

I think the only issue is inadequate airflow at idle.  I am confident the shroud with a proper size fan will help a lot.   An 18" to 18-1/2" fan will give about 3/4 to 1" clearance on all sides, which should be okay according to a number of sources.

I am hoping you guys will have a suggestions before I buy a fan.  I think the original 7-blade fan is 18-3/8", but it would likely be hard to find one.   What about an aftermarket fan or flex fan?   I'm tempted to try a Flex-a-lite.  I know some people love them and others hate them, but they've been in business for at least 40 years so they might be fine.

By the way, I measured the tilt of the components - it isn't as much as I thought.   The bottom of the fan will be about 1/2" deeper into the shroud than the top of the fan.  The existing 2-1/4" spacer will locate the fan about centered in the edge of the opening.   

Thanks for any help.

-Stu

Offline 70chall440

  • Sr. Resident
  • ******
  • Posts: 6184
Re: Fan and Shroud
« Reply #3 on: August 13, 2020 - 12:03:26 AM »
The fan should definitely be inside the shroud. As far as finding a fan, I do not think that is as big a deal as you are thinking. There as some "rare" fans out there but that isn't what you are after.

Here is a 19" fan
https://www.summitracing.com/parts/rnb-621-323?seid=srese1&gclid=CjwKCAjwps75BRAcEiwAEiACMSdgQkbT-ers96GGEM7LlOk2npWyWMeN_48t2fFpZgnGtTIDB2rfExoC-4QQAvD_BwE

Here is a 17" fan
https://www.summitracing.com/parts/der-17317?seid=srese1&gclid=CjwKCAjwps75BRAcEiwAEiACMaGw7kJAV2xb8_DufFrtOCrs7RI2CvsdlLa7m2vswtV0pEmbK5RqqhoCyNYQAvD_BwE

There are lots out there, just google Mopar 18" fan...
Current Mopar
70 Challenger RT 440-6 EFI, 73 Cuda 416-6 EFI
05 Hemi Durango, 01 Ram 4x4, 14 Ram 2500 4X4, 10 PCP Challenger 6 spd RT, 01 Viper GTS ACR, 52 B3B w/330 Desoto Hemi, 70 Hemi RR (under const)
Past Mopars
9 x Challengers. AAR Cuda, 4 RR, 2 GTX, 4 Chargers, etc... (too many to list)