I foolishly removed the original fan some 35 years ago no longer have it.

I could use some recommendations for an aftermarket replacement fan blade.

There are several 5 & 7 blade aftermarket blades out there but can’t seem to find one specific for 68, I would think a 66-67 or 69-70 would work? I have read it takes 17.5" and 18" is the correct size.

This is a 68 427 w/ factory AC , I do have a Dewitt’s aluminum radiator, currently running an electric fan. I was planning on purchasing a fiberglass replacement shroud as well.

Thanks in advance, Mike

 

3955182 is the GM part number for your C3.

 

I don't have a dog in this fight, but I'm curious why you are going back to a clutch driven fan. Is there something wrong with your electric setup?

 

Thank you sir for this most valuable information. I have found a few original fan blades but I'm not willing to pay that much at this point, I think Corvette Central may have some replacements but they list them for 66-67 69-70 so this was some of my confusion.
I'll follow up with this hunt.

Thanks Mike

 

The more dogs the better!
I suspect I may have other issues with cooling. The original motor was either never in the car when dad purchased the car in 72 or when it was rebuilt in 74 and swapped by the machine shop or garage. Currently from best of my memory: I have 66 oval port heads with a later MIV block original 390 HP alum intake, this is a full roller motor and runs well, tot vac adv is close to 50 deg +- Mixture seams to be fine. The electric fan set up is a 2 speed from a Ford Torus, running dual temp sensors and relays.
The temp sensors a 190 & 210 I have tried several of them already and are located in one of those housing above the 180 deg T-Stat. The car will sit an ideal in hot weather with the fan cycling as it should. I have all the correct weather striping ect around the radiator. Running down the road at any speed the fan constantly runs. bring it to a stop for a while and it will cycle fine. 70mph the temp will rise to around 210 w/ AC on so I suspected the shroud was blocking to much air and opened it up with some spring hinged flaps that did seam to help some. So the main reason I want to go back to stock as the constant running of the fan especially at night with the head lights, AC (Sanden) turned on it loads the one wire high output alternator down to more than my liking.

Thanks Mike

 

 

Well, if you don't mind more dogs kibbitzing...

Have a read through this thread. The OP had a similar issue.

https://www.corvetteforum.com/forums...is-cursed.html

My preference is always to throw more electons at a problem, so my advive is biased towards that. If your alternator can't hang, that's an easy fix. But if you are overheating driving down the road now, I'm not sure that changing your fan will fix that. I'd look elsewhere first.

 

Nice engine!
seems to me you may need relief flaps in shroud to let more air in at speed?
that air needs to jam through that fan area and maybe flaps will get some more heat transfer..
edit..yes same as link above..also besure air dams are under car as well

 

I have an 18” (17-7/8”) 5 blade with a new HD clutch I can sell you.

 

I'm the OP of the thread that @Bikespace referenced. I just went through this hell...

I'm not seeing any other places on that shroud where air can pass through other than the fan opening. As I learned in my thread, the shallow shrouds (like yours) or the flat ones (like mine) with a single fan CAN work, but there needs to be places other than the single fan opening for air to be able to pass through. Air that passes through the rad at either end furthest away from the fan opening has to make one hell of a turn to be able to head towards and go through the fan opening. The more you force a fluid (air) to bend or turn, the less it wants to flow. At freeway speeds, the air will stall or "pack up" between the back of the rad and the shroud because it can't make that turn fast enough and move through the fan opening. The fan running while driving helps pull that air through at speed and the rad works like it's supposed to, but the fan shouldn't have to run while cruising down the road at anywhere north of say 40-45 mph, depending on your ambient temp.

You said you already added some spring loaded flaps, but where and how many? How strong are those springs? It may have not been enough. Adding the passive rubber flaps like these in other spots may be the ticket. These are what I added to my flat shroud with a single 16" fan.

 

All,

Thanks for all the good info and suggestions, fortunately I have a few months before it gets hot and will have plenty of time to try and skin this Cat.

I installed the electric fan/shroud so it can be easily removed, I'll bolt on and old flex fan I have and take it for a ride down the interstate to see how much difference that makes,

Again, Thanks !

 

Flexfan? Flexfan? Old flexfan?

It would be safer to drive with three lug-nuts per wheel than to run a flexfan.

 

.
just temporary to check if my electric fan shroud is to restrictive

 

it’s old. All metal ran it for over 20 yrs on 327.

 

.
the problem was: the after market 2 speed Taurus fan set up. Way over shrouded as suggested.