1968 427 fan

[Pete G.]

Hello, I'm in the process of rebuilding my L68 w/ AC. It currently has a after market fan on it that I want to replace with OEM correct fan. All I have read indicate the factory installed fan (5 blade, part #3888366) was post factory recommended to be replaced with a 7 blade version (part #3955182) due to overheating issues with 5 blade fan on AC car.

My question is, since the 7 blade fan was recommended by GM post factory, does it matter for judging what date code I use? I believe this 7 blade fan was produced by GM for many years (at least into the 90's), the early versions of the fan (date codes I've viewed are J66 and I68) go for between $450 and $750 on eBay and don't match too well to the car's build date, can likely find a newer specimen for a lot less but don't wish to lose points in judging.

What should I do?

Thanks!

[Grant W.]

Re: 1968 427 fan

Hi Pete
Last year I had a very long email correspondence with Joe regarding some of the fan blades I had.
For 68 small block AC the correct fan blade is 3789562 It was also used for the 68 Camaro with AC
I had thought this fan blade was correct for my 68 B/B but as it turned out the correct one for my car is 3888366

So after collecting for 10 years or more I had 4 of these 3789562's They were hard to find. I just sold my last one last week. Sorry I wish you had posted it earlier.

You can put a 7 blade but will get points deducted as a replacement.

You can put a 3888366 and that is close but not 100% correct. To the untrained judge he may not beable to spot an original 3789562

I just sold a 3888366 for 495.00 I have about 5 or 6 loose ones and some with original fan clutches.

You can pm me if you want an original 7 blade to get you by for now.
Thanks, Grant

[Joe L.]

Re: 1968 427 fan

Hello, I'm in the process of rebuilding my L68 w/ AC. It currently has a after market fan on it that I want to replace with OEM correct fan. All I have read indicate the factory installed fan (5 blade, part #3888366) was post factory recommended to be replaced with a 7 blade version (part #3955182) due to overheating issues with 5 blade fan on AC car.

My question is, since the 7 blade fan was recommended by GM post factory, does it matter for judging what date code I use? I believe this 7 blade fan was produced by GM for many years (at least into the 90's), the early versions of the fan (date codes I've viewed are J66 and I68) go for between $450 and $750 on eBay and don't match too well to the car's build date, can likely find a newer specimen for a lot less but don't wish to lose points in judging.

What should I do?

Thanks!

Pete-----


The GM #3955182 fan blade assembly was never used for any 1968 Corvettes and, as a matter of fact, didn't even exist when 1968 Corvettes were being built. So, not only is a 3955182 not correct for a 1968 but there won't be a single one out there with a date that would be correct for a 1968. That really would not matter since if the fan is incorrect, I don't think you'd get any credit for a correct date code assuming you could find one. But, that's a moot point since you'd never be able to find a correct date. Also, I don't think there's any credit given for an incorrect date that's "closer to a correct date". So, if you decide to use a 3955182 I think any date will be as good as any other.

As far as a 7 blade 3955182 providing better cooling than a 5 blade 3888366, I don't think the difference is significant. In fact, I KNOW it's not. Many years ago I changed the original GM #3888366 on my original owner 1969 Corvette small block to a GM #3955182 in order to improve cooling. The change produced no significant, if any, difference in cooling.

[Dale C.]

Re: 1968 427 fan

Joe
Wasn't there a difference in the fans pitch on the BB A/C and non A/C cars? That made a difference in the airflow.
Dale

[Joe L.]

Re: 1968 427 fan

Joe
Wasn't there a difference in the fans pitch on the BB A/C and non A/C cars? That made a difference in the airflow.
Dale

Dale------


Not if we're talking about 1968. 1968 big blocks used fan GM #3888366 whether equipped with C-60, or not. For 1969 things changed, though. For 1969 big block with C-60 fan GM #3955182 was used while the 3888366 was used for non C-60.

[Pete G.]

Re: 1968 427 fan

Thanks for all the feedback!

I see now that 3888366 was applied to all '68 configurations. Interesting re: the 7 blade version 3955182 as I see currently advertised in eBay http://cgi.ebay.com/ebaymotors/66-69...-/120621371751 date coded I66 that seems to be for '66-'67 setups w/ A/C. Wonder why GM went from 7 blade application in '66-'67 to 5 blade model in '68 then back to 7 blade fan for '69? It seems there would be some cooling advantage of 7 blades over 5 blades, why else would GM revert back to 7 blade in '69?
Anyway, for judging w/o deduction need to acquire the 5 blade 3888366. Grant, seems you have a couple of these available, I'll be in touch!

Thanks again for all the info., very helpful!

[Joe L.]

Re: 1968 427 fan

Thanks for all the feedback!

I see now that 3888366 was applied to all '68 configurations. Interesting re: the 7 blade version 3955182 as I see currently advertised in eBay http://cgi.ebay.com/ebaymotors/66-69...-/120621371751 date coded I66 that seems to be for '66-'67 setups w/ A/C. Wonder why GM went from 7 blade application in '66-'67 to 5 blade model in '68 then back to 7 blade fan for '69? It seems there would be some cooling advantage of 7 blades over 5 blades, why else would GM revert back to 7 blade in '69?
Anyway, for judging w/o deduction need to acquire the 5 blade 3888366. Grant, seems you have a couple of these available, I'll be in touch!

Thanks again for all the info., very helpful!

Pete------


I don't know what the date code on this piece means, but it's definitely not 1966. The 3955182 fan blade assembly did not even exist in 1966. It didn't exist in 1967 or during the 1968 model year, either. It was released in late 1968 for first use on the 1969 model year.

[Wayne M.]

Re: 1968 427 fan

Hello, I'm in the process of rebuilding my L68 w/ AC. It currently has a after market fan on it that I want to replace with OEM correct fan. All I have read indicate the factory installed fan (5 blade, part #3888366) was post factory recommended to be replaced with a 7 blade version (part #3955182) due to overheating issues with 5 blade fan on AC car. .....

Pete, if your concern is just a general overheating problem with the 1967 427 / C60 combo, are you familiar with the raft of factory mods done to the early cars ? There's a Tech Service Bulletin issued in Dec of 1967, covering just about everything EXCEPT changing the fan blade assembly.

Examples: after VIN 00720, new pulley to increase fan speed; add slots in front valance panel (see pic below).

after VIN 01344 added new fan clutch to increase the slip speed.

after VIN 02469, added full fan shroud.

Your car is probably later than these, and therefore should have all these modifications.





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