17.5” x 7 blade fan for 74 BB

Knodty

Knodty

Well-known user
Hi Guys it’s been a while since I was last on here.
Anyone know if someone has a 17.5” x 7 blade fan for 74 BB, for sale in the uk?
I’ve finally had enough of the endless problems with the Twin Spal fans I fitted to my BB about 20 years ago.

Ideally I need a viscous coupling and Shroud as well?

Cheers
 
Roscobbc

Roscobbc

Moderator
Do some research on fiscous coupling Pete - Rock Auto isn't a bad place to start. It appears that there are three spec's available - standard duty - heavy duty - extreme duty. Guessing that extreme duty is for 454 (perhaps 502) big blocks in truck. Presume that standard duty will be lo-po small blocks and heavy duty big blocks and hi-po small blocks. The manufacturers don't appear to publish much info on rpm/temperature the coupling 'locks' at. Guessing you (like me) will need a heavy duty unit. Later big block cars with smog crap and a/c I seem to recall struggle with cooling. Have you still got your OEM shroud? - you'll need that!
 
Knodty

Knodty

Well-known user
Roscobbc said:
Do some research on fiscous coupling Pete - Rock Auto isn't a bad place to start. It appears that there are three spec's available - standard duty - heavy duty - extreme duty. Guessing that extreme duty is for 454 (perhaps 502) big blocks in truck. Presume that standard duty will be lo-po small blocks and heavy duty big blocks and hi-po small blocks. The manufacturers don't appear to publish much info on rpm/temperature the coupling 'locks' at. Guessing you (like me) will need a heavy duty unit. Later big block cars with smog crap and a/c I seem to recall struggle with cooling. Have you still got your OEM shroud? - you'll need that!
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I did see the ones available at Rock Auto and was going to use that as a last resort, if I can’t get something cheaper over here. Some suppliers are asking silly money for original fans in excess of $1000. (Wish I hadn’t sold mine to Claremont Corvette for £20 back in the day. 😖 Mine did originally come with air con and had a 7 blade fan as standard. I seem to have read that all air con cars had a 7 blade fan, and non AC cars a 5 blade. I don’t really want to fit another flexi fan as a result of what happened to mine before. However I might do that as a cheaper option until I have a bit of spare cash.
 
Roscobbc

Roscobbc

Moderator
Mine is a 5 blade fan. Bought a new viscous coupling two or three years ago after seeing it leak fluid.....can't recall whether I bought it from Rock or Customville.
Btw you will definitely need a OEM shroud to get the best efficiency from the set-up.
 
Knodty

Knodty

Well-known user
Roscobbc said:
Mine is a 5 blade fan. Bought a new viscous coupling two or three years ago after seeing it leak fluid.....can't recall whether I bought it from Rock or Customville.
Btw you will definitely need a OEM shroud to get the best efficiency from the set-up.
Click to expand...
Yes I will for sure. Just wish I still had a usable old shroud.
 
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