1966 427 390 HP w/AC Fan Blade Info

**Wayne M.** · August 28, 2009, 06:07 PM

Re: 1966 427 390 HP w/AC Fan Blade Info

Originally posted by Mike Browning (24893)

.... Can anyone please shed more light on the proper fan blade for an air conditioned big block '66? The blade that was on her in '88 may very well be the original. Its a 5 blade fan with triangular arms attatched with flat rivets. Pretty sure its 17.5". The blade lengths and widths all jive with Noland Adams specs. BUT, the only marks on this blade are: "FRONT" and "H". There's no "66" on the center ring or a "W" anywhere on the blades. The VIN is about 7200, built Dec 1st, '65. Any help would be much appreciated!! Oh yeah, some good info/pics of a BB fan clutch circa this car would be great too! Thanks, Mike

Mike -- according to Oct '66 P&A30 parts book, there's only the 3888366 5-blade (for both C60 and non-air big blocks) or the 3770529 (5-blade) for small blocks. There's a 3rd one listed; the 7-blade 3853943 which is normally associated with '64-5 air cars, but is nevertheless, called out as '64-6 w/C.A.C, (first design).

Anyway, attached links to comparison (side view between a "66" with W and Front, and a '529', to show difference in blade pitch.

Am not aware of any other fan for a BB air 1966. Does yours have 5 rivets per spider ? I've added a 2nd and 3rd pic link of my "366" fan for detail.

**David L.** · August 28, 2009, 09:34 PM

Re: 1966 427 390 HP w/AC Fan Blade Info

Mike,
The 3888366 fan was made by Hayes-Albion and stamped "H" (for Hayes-Albion), "FRONT", and "66" (part of the Hayes-Albion part number, not part of the GM part number). To determine the diameter of your fan measure the radius (center of hub hole to tip of blade). It should be 8 3/4" for a 17 1/2" fan. The pitch should measure 2 1/4". Put the fan on a flat table and measure the vertical distance to the highest part of any blade.

The 327 fan (GM #3770529) is a 17 1/8" dia. fan (r = 8 9/16") and has a pitch of 1 5/8".

The bolt circle should be 3" with a 2 3/8" dia. hub hole.

I have studied Chev.-Corvette-Camaro-Chevelle fans for over 30 years and have about 40 to 50 muscle car era fans in my "collection".

Dave

**Wayne M.** · August 29, 2009, 08:03 AM

Re: 1966 427 390 HP w/AC Fan Blade Info

Originally posted by David Liukkonen (3775)

I have studied Chev.-Corvette-Camaro-Chevelle fans for over 30 years and have about 40 to 50 muscle car era fans in my "collection".
Dave

Good info, Dave -- any ideas as to what the "W" on the back of one of the spiders stands for ?

**Timothy B.** · August 29, 2009, 08:31 AM

Re: 1966 427 390 HP w/AC Fan Blade Info

Dave,

That's great information, when looking at the fans sometimes they all look the same to me..

I am glad we have a archives here because this is the kind of information I would need to refresh myself about.

**David L.** · August 29, 2009, 10:05 AM

Re: 1966 427 390 HP w/AC Fan Blade Info

Originally posted by Wayne Midkiff (3437)

Good info, Dave -- any ideas as to what the "W" on the back of one of the spiders stands for ?

Wayne,

I have had many Hayes-Albion fans over the years (both 5 and 7 blade) and still have some in my "collection" but I have never been able to figure out what the letter "W" represents.

The Schwitzer fans generally, but NOT always, have a Schwitzer part number, date code, and sometimes the GM part number stamped on the blades.

Dave

**Wayne M.** · August 29, 2009, 11:27 AM

Re: 1966 427 390 HP w/AC Fan Blade Info

Originally posted by Mike Browning (24893)

...... Any help would be much appreciated!! Oh yeah, some good info/pics of a BB fan clutch circa this car would be great too! Thanks, Mike

Mike -- Big long thread on clutches and fans back in October of 2006; lots of pics. Here's the link.

https://www.forums.ncrs.org/showthre...66139&uid=6710

**Mike B.** · August 30, 2009, 09:01 PM

Re: 1966 427 390 HP w/AC Fan Blade Info

Originally posted by Wayne Midkiff (3437)

Mike -- according to Oct '66 P&A30 parts book, there's only the 3888366 5-blade (for both C60 and non-air big blocks) or the 3770529 (5-blade) for small blocks. There's a 3rd one listed; the 7-blade 3853943 which is normally associated with '64-5 air cars, but is nevertheless, called out as '64-6 w/C.A.C, (first design).

Anyway, attached links to comparison (side view between a "66" with W and Front, and a '529', to show difference in blade pitch.

Am not aware of any other fan for a BB air 1966. Does yours have 5 rivets per spider ? I've added a 2nd and 3rd pic link of my "366" fan for detail.

Hey Wayne - Thanks for the description and pics. My blade in question looks identical to the upper "366" that you show above the "529". I've got the "529" on my '65 350hp car. The blade pitch looks the same as yours. The rivets too. Just the absence of the "66" and "W". I'm not sure of the pitch. Thanks for all your help. Mike

**Mike B.** · August 30, 2009, 09:15 PM

Re: 1966 427 390 HP w/AC Fan Blade Info

Originally posted by David Liukkonen (3775)

Mike,
The 3888366 fan was made by Hayes-Albion and stamped "H" (for Hayes-Albion), "FRONT", and "66" (part of the Hayes-Albion part number, not part of the GM part number). To determine the diameter of your fan measure the radius (center of hub hole to tip of blade). It should be 8 3/4" for a 17 1/2" fan. The pitch should measure 2 1/4". Put the fan on a flat table and measure the vertical distance to the highest part of any blade.

The 327 fan (GM #3770529) is a 17 1/8" dia. fan (r = 8 9/16") and has a pitch of 1 5/8".

The bolt circle should be 3" with a 2 3/8" dia. hub hole.

I have studied Chev.-Corvette-Camaro-Chevelle fans for over 30 years and have about 40 to 50 muscle car era fans in my "collection".

Dave

Hey Dave - Thanks for the info. I just got off the phone with a friend who has a 425hp '66. All your measurements jive with my buddy's fan. Not mine. Pitch is a little shy and the blade appears to be 17 1/8" at the most. Rivets the same, but no "66" or "W". Thanks for the help. My research continues. Mike

**Mike B.** · September 2, 2009, 09:13 PM

Re: 1966 427 390 HP w/AC Fan Blade Info

Thanks to everyone for their information about '66 427 fan blades. It sure sounds like I should have a 3888366 which is 17 1/2" in diameter with flat rivets and higher pitch. It should have an "H", "FRONT", "66" and "W" stamped into the blade. I suppose I'll start hunting for one.

The BIG question is: Why does the 4th Edition '66 Judging Guide state on page 102 that the big block "fan blade assembly is part number 3872792 which is a five blade assembly attached to the center with five flat head rivets per blade. The blades are 4.00 by 5.68 inches before shaping with an overall diameter of 17.0 inches."

After mulling over the great info you all supplied me, I closely measured the blade again and found it to be exactly as stated in the JG. Definately 17.0 inches, flat rivets, high pitch with only "FRONT" and "H" stamps. What was their source for this info? Was it a mistake? The 5th Edition '65 JG page 137 states the same info for the 396 fan blade. My car was finished Dec. 1st, '65.

Could this be a leftover from the '65 production run? Why does the '66 JG contradict the parts manual info? Any last thoughts from all my gear head friends?

Mike

**Joe L.** · September 2, 2009, 09:47 PM

Re: 1966 427 390 HP w/AC Fan Blade Info

Originally posted by Mike Browning (24893)

Thanks to everyone for their information about '66 427 fan blades. It sure sounds like I should have a 3888366 which is 17 1/2" in diameter with flat rivets and higher pitch. It should have an "H", "FRONT", "66" and "W" stamped into the blade. I suppose I'll start hunting for one.

The BIG question is: Why does the 4th Edition '66 Judging Guide state on page 102 that the big block "fan blade assembly is part number 3872792 which is a five blade assembly attached to the center with five flat head rivets per blade. The blades are 4.00 by 5.68 inches before shaping with an overall diameter of 17.0 inches."

After mulling over the great info you all supplied me, I closely measured the blade again and found it to be exactly as stated in the JG. Definately 17.0 inches, flat rivets, high pitch with only "FRONT" and "H" stamps. What was their source for this info? Was it a mistake? The 5th Edition '65 JG page 137 states the same info for the 396 fan blade. My car was finished Dec. 1st, '65.

Could this be a leftover from the '65 production run? Why does the '66 JG contradict the parts manual info? Any last thoughts from all my gear head friends?

Mike

Mike-----

I would not rule out the possibility of the GM #3872792 fan blade assembly being used for early 1966. However, I'm virtually certain it was not used for the vast majority of 1966 Corvettes built. So, if your car is a very early car, then I'd say it's possible it was originally fitted with the 3872792.

I believe the primary difference between the 3872792 and the 3888366 is the 1/2" difference in OD. I believe the blade pitch was the same or near the same. So, if you have a fan blade assembly that's 17" OD and with a blade pitch similar to the 3888366 pictured above, then you likely have a 3872792 and, I'd say, it's likely original to the car. The 3872792 is a VERY difficult fan blade assembly to find and it's very doubtful it got on the car by accident.

The 3872792 did not have a "66" stamped on it.

**Wayne M.** · September 3, 2009, 02:10 PM

Re: 1966 427 390 HP w/AC Fan Blade Info

Originally posted by Joe Lucia (12484)

.... I would not rule out the possibility of the GM #3872792 fan blade assembly being used for early 1966. However, I'm virtually certain it was not used for the vast majority of 1966 Corvettes built. So, if your car is a very early car, then I'd say it's possible it was originally fitted with the 3872792.

I believe the primary difference between the 3872792 and the 3888366 is the 1/2" difference in OD. I believe the blade pitch was the same or near the same. So, if you have a fan blade assembly that's 17" OD and with a blade pitch similar to the 3888366 pictured above, then you likely have a 3872792 and, I'd say, it's likely original to the car. The 3872792 is a VERY difficult fan blade assembly to find and it's very doubtful it got on the car by accident.

Mike, Joe --- lot of strange things here ('66 TIM&JG; Oct '65 [first issue of 1966 MY] P&A30 showing neither the '792' or the '366'; only the small block fan assy's '529' and 7-blade '943').

And the fan shown in my big pics is NOT 17.5" dia., but rather 17_1/8". My '65 L78 was in a front-ender in 1970, and I suspect the blade assy is a service replacement. Both the '792' and the '366' were still listed in the Jan 1970 P&A30B catalog, but here's my theory: the '366' GM drawing from Noland's Vol 2 (big scans below) has a notation "similar to 3872792".

I believe the two were EXACT except for the diameter (17.5" would have been too tight a fit on the 396 fan shroud). So when initial '65 stock of the L78 fan was exhausted, for service they used the same 'spider/hub' for both '65 and '66 BB, but just shorter blades on the '792'. That might explain why I have a short-bladed '366'. The blade lengths on the drawings for the L78 are 5.68" and for the "366" is 5.93"; exactly 1/4" longer (per blade) which accounts for the half-inch greater diameter of the 1966 BB assembly.

Anyhow; open to comments

.

**Mike B.** · September 3, 2009, 03:40 PM

Re: 1966 427 390 HP w/AC Fan Blade Info

Wayne and Joe,

Excellent information. This clears alot up. I'm just about convinced that my fan is a 3872792 blade. Why it ended up on my early December car is a bit of a mystery. She was in a front-ender back in the mid 70s, but from the photos I have of her in that state, I think the fan survived.

I took some close-ups of the fan for your review, but I'm having trouble reducing the size for attachment. As soon as I get a reply from the help desk I'll send them out. Or Wayne, would you tell me how? Could you send me an e-mail? Looks like you've got it down to a science.

Thanks again,
Mike

**Wayne M.** · September 3, 2009, 04:05 PM

Re: 1966 427 390 HP w/AC Fan Blade Info

Originally posted by Mike Browning (24893)

.

... I took some close-ups of the fan for your review, but I'm having trouble reducing the size for attachment. As soon as I get a reply from the help desk I'll send them out. Or Wayne, would you tell me how? Could you send me an e-mail? .....

Mike -- yes; email them to me at midstyle@3web.net Hope they're not over a couple of megabytes each, 'cause I'm (still) on a 56K dial-up ISP. Then two ways to go -- either I reduce to under the DB limits and email them back to you; or, depending on the resolution and detail, I could post them to MY Photobucket hosting account (like those 2 big close-up pics) and send you the links so you could attach them in your own thread.

**Mike B.** · September 4, 2009, 07:28 PM

Re: 1966 427 390 HP w/AC Fan Blade Info

Thanks to Wayne Midkiff, these shots have been reduced in size for your review. Please chime in with any comments you may have. I'm now thinking this fan is a 3872792 blade and may be original to my '66.

Thanks again for all your help,

Mike

427_Fan_Blade_Shots_002_(Custom).jpg

427_Fan_Blade_Shots_003_(Custom).jpg

427_Fan_Blade_Shots_004_(Custom).jpg

427_Fan_Blade_Shots_007_(Custom).jpg

1966 427 390 HP w/AC Fan Blade Info

1966 427 390 HP w/AC Fan Blade Info

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