1967 327 w/ AC fan rivets

[Patrick H.]

I have done a lot of reading of past posts going back 20 years in search of the proper information regarding the engine cooling fan for a 1967 small block with AC. The car I am working on has a 7-blade big block fan, which is not correct.

Those past posts indicate that by 1965 the 5-blade fan moved from a mushroom-shaped (or rounded) rivet to a flat rivet, and that for Corvettes they used 4 rivets to retain each fan blade.
The current 1967 Judging Guide, however, says “Air-conditioned Small Block fans were either one of two assemblies. Both have five blades with an overall diameter of 18" and use five mushroom head rivets to attach each blade to a reinforcement arm.”

Is the judging guide incorrect with regard to the configuration and number of rivets used in 1967 small block w/AC cars?

Thanks.

[Tony S.]

Patrick. Just a clarification on 65 fans. All non-A/C cars have a 5-blade fan including L78. The 65 A/C fan is a 7-blade fan. If you are utilizing the 65 TIM/JG as a reference for a '67, I'm not sure if the same holds true for '67.

Tony

[Patrick H.]

Tony,

The reference was to 20 years of posts on the forum that suggested the round/mushroom rivets changed to the flat configuration by early 1965.

My quote is from the 1967 manual.

FYI the search feature on this new board format is very robust. I found it very easy to find data on the 3789562 fan. However, that data doesn’t seem to match the 1967 manual.

Here is an example:

https://www.forums.ncrs.org/forum/technical-discussion/118893-67-fan-blades

[Daniel Y.]

Pat - 67 fans are entirely different configuration. see page 174 of the TIM&JG

5. Engine Cooling System
Fan
Small Block
Non-air-conditioned Small Block cars use a 5-blade fan assembly part number 3770529 with an overall diameter
of 17-1/8”. Five flat head rivets attach each blade to an elongated triangular shape reinforcement arm on the fan
spider. The center of the reinforcement has an “H” stamped on the front, not visible when installed and one of
the reinforcement arms has a “W” stamped on the rear.
Air-conditioned Small Block fans were either one of two assemblies. Both have five blades with an overall
diameter of 18" and use five mushroom head rivets to attach each blade to a reinforcement arm. The arms of fan
assembly part number 3789562 have an elongated triangular shape with the front of the reinforcement having
an “H” stamped in the center.
Fan assembly part number 3863137 reinforcement arms have a rectangular shape. The front of each blade has
a manufacture date, a blade part number and a manufacturer’s code stamped on three lines near one of the
corners. The date format is M-Y where M is the month, A-L and Y is the last digit of the year. A March 1967
example is:
C7
912239
SC
Big Block
The fan blade assembly for all Big Blocks, with or without air-conditioning, is part number 3888366 with five
blades attached to each center reinforcement arm on the fan spider with five flat head rivets per blade. A “W”
logo is stamped into the rear of one arm of the center reinforcement. Each blade is 4" by 5.68" with an overall
diameter of 17-½”.

[Leif A.]

Pictures of my 3789562 from my '67 factory A/C, factory power steering car. Fan is 18" in diameter.

[Patrick H.]

Dan Y. -

That’s the same verbiage I copied.
The question remains- do 67 AC fans (3789562) have 5 rivets or 4? Flat rivets or round?

My point was that 20 years of discussion board data on fans doesn’t match the 67 JG. Please read the linked thread. It infers that pre-65 rivets were round/mushroom heads, post-65 were flat, and Corvettes used 4 rivets, not 5. I’m not saying that the thread linked is correct, but it summarizes the many others on the subject.
Dave Liukkonen in that thread and others suggests 4 flat rivets.

If we’re going to buy one, I want it to be the right one.

Leif A. - known original to the car? Flat or rounded head rivets?

[Leif A.]

Dan Y. -

That’s the same verbiage I copied.
The question remains- do 67 AC fans (3789562) have 5 rivets or 4? Flat rivets or round?

My point was that 20 years of discussion board data on fans doesn’t match the 67 JG. Please read the linked thread. It infers that pre-65 rivets were round/mushroom heads, post-65 were flat, and Corvettes used 4 rivets, not 5. I’m not saying that the thread linked is correct, but it summarizes the many others on the subject.
Dave Liukkonen in that thread and others suggests 4 flat rivets.

If we’re going to buy one, I want it to be the right one.

Leif A. - known original to the car? Flat or rounded head rivets?

Patrick,
I didn't buy the car new in '67 so I can't speak to your first question. The rivets are rounded/mushroom heads on the front side...see pics.

[Garry B.]

Joe Tripoli wrote an excellent article in a Restorer magazine several months back on a great span of radiator fans.. It's the issue with the black '55(?) on the front with the lovely lade posing with it on the cover. I referenced that article recently because I received a point deduct on my small block AC car at National for the fan blade not having a W stamp. Joe's article makes mention of the W on non-AC cars, but no mention of the W stamp on AC cars. I also have looked for the W on my 4 Star Bowtie '67 factory small block AC car and cannot find any sign of a W stamp on it either. Above, Dan makes no mention of the W on AC fans either. One point is no big deal, but it's important when trying to verify original fans and their application. The message is conflicting.

[Patrick H.]

Thanks Leif.

Just trying to determine between 20 years of DB posts and the JG which description is correct.

[Patrick H.]

I referenced that article recently because I received a point deduct on my small block AC car at National for the fan blade not having a W stamp. Joe's article makes mention of the W on non-AC cars, but no mention of the W stamp on AC cars. I also have looked for the W on my 4 Star Bowtie '67 factory small block AC car and cannot find any sign of a W stamp on it either. Above, Dan makes no mention of the W on AC fans either. One point is no big deal, but it's important when trying to verify original fans and their application. The message is conflicting.

Garry,

How many rivets, and what configuration are they on your Bowtie car?

[Garry B.]

Garry,

How many rivets, and what configuration are they on your Bowtie car?

Patrick, here are a couple of photos from my 4 star BT car of front and back of fan. The '67 is a small block 300hp with factory AC which I believe addresses the OP.

[Daniel Y.]

Please read my post. I copied from the new TIM&JG non AC cars 5 flat rivets. AC cars 5 Mushroom head rivets. Leif posted pictures of his AC fan. it has the right configuration - 5 mushroom head rivets

if you car is non AC - it should be 5 flat rivets

hopefully that will answer you question.

[Rocco S.]

Patrick,

I also have a 1967 L79 with A/C. I purchased the car from the original owner about 10 years ago, who has since passed. So I can't ask any questions.

When I got the car it was fitted with a 7-blade fan which I thought was incorrect since it had a 1972 date code and a big block Schwitzer fan clutch (1966 date code) which has a shorter shaft than the small block fan. Therefore, the fan was not properly centered in the shroud but never experienced any overheating.

So I was on the search for a correct fan and fan clutch. I regularly visited a small old-time salvage yard and the owner gave me free run of the place. In their back room was a pile of fans and clutches, none newer than the 1970's. I thought I struck gold when I uncovered an 18", 5-blade fan connected to a correct small block Schwitzer clutch. Neither the fan or clutch were marked with a part number or date code. It did have the triangular arms with 5 rivets. The yard marked it with white ink "1968". $50.00 later and I thought I got a good deal.

I sent the clutch to McConnell (sp?) for a rebuild and he stamped the hub with a Jan 67 date code for me. The fan cleaned up nice and was painted semigloss black. The "correct" assembly was installed and has been working great. No overheating. Why the original owner installed a 7-blade fan and incorrect clutch is unknown.

After reading the 1967 judging manual I believe the fan is correct. However, I'm not sure if the rivets are the correct style. I have attached a few photos for all to review. This is the first time uploading photos with the new format. Hopefully I did it correctly.

Any feedback is appreciated.

[Garry B.]

I would like to add some additional information. I agree that the fan blade photos that Leif provided are what I know to be "one" of the correct configurations of fan blades and corroborated by Dan and others. One of my 67's AC small block cars has exactly the same fan blade. But, as the 8th edition of the JG also draws out, and supported by Joe Triopli's research and Dan's post, there was another 18" fan blade part number 3863137 used on '67 small block AC cars. It goes on to illustrate a stamp on this fan that had a part number (different than the GM part number of 386137 as used in the AIM) of 912239 with a date code and SC stamped on each blade of the fan. I have attached a photo of the fan blade on my 4 Star BT car that clearly aligns with the JG and with Joe's research that mine fan is different in some respects to Leif's, but still correct. I have also included just a portion of Joe's report published in the Volume 48, Number 1, Summer 2021 of the Restorer Magazine.

My point is the shape of these two fan blades used for this application do differ as shown in my prior photo, but they both have mushroom rivets and are 18" in diameter. So the JG is spot on (thanks Dan), but I didn't want readers of this thread to think that unless their fan looked like Leif's, that they have the wrong fan.
IMG_4455.jpg IMG_4457.jpg

[Patrick H.]

Please read my post. I copied from the new TIM&JG non AC cars 5 flat rivets. AC cars 5 Mushroom head rivets. Leif posted pictures of his AC fan. it has the right configuration - 5 mushroom head rivets

if you car is non AC - it should be 5 flat rivets

hopefully that will answer you question.

Once again, I am aware what’s in the JG. I posted it, you posted it. Reading it again is not what I was after and does not answer my original question.

As it differed from what was described on many posts on the DB here, I was looking for clarification that the JG was, in fact, correct. They JGs have been known to be wrong, and before we spent any money I just wanted to be sure what we should look for in a fan.
It appears that an 18 inch fan with round/mushroom head rivets in a “5 of diamonds (or clubs or…)” configuration is correct.

So, my conclusion is that the current 67 JG is correct, and some of the posts on the DB over the years are not. That’s what I wanted to know, and thanks to all of those who posted pictures of their fans, or sent them to me directly.

PH