Picture of a correct fan clutch for a '65 396/425

[Jonathan S.]

All,

I have a '65 judge manual, but unlike the '62 judging manual there are no pictures for correct fan clutches. I have read the words, but I am not very good a visualizing the description.

Does anyone have pictures of what the correct fan clutch looks like for a '65 396/425 car? If so, can you either post or PM them to me.

Thanks in advance.

[Wayne M.]

Re: Picture of a correct fan clutch for a '65 396/425

Here's a couple of pics of what COULD be typical production for 1965 (no differentiation between clutch manufacture source for L78 or the small blocks). This is the Eaton design, with the spiral coil. You can see a faint "CK" ink stamp. There's also an ink date stamp "A3 ?" which will not decode to the '65 model year. There's also a Schweitzer (sp?) design [no pic] with a bimetallic strip, that IIRC, has a stepped shaft.

Notice the straight shaft, which is 0.3" shorter than the "CJ" stamped clutch for a small block, whether the Eaton or Schweitzer supplier.

[John H.]

Re: Picture of a correct fan clutch for a '65 396/425

There's also a Schweitzer (sp?) design [no pic] with a bimetallic strip, that IIRC, has a stepped shaft.

Here are photos of the Schwitzer "bar" clutch; this and the Eaton "coil" clutch were used interchangeably on both small-block and big-block applications (short shafts on big-blocks, longer shafts on small-blocks). Most Schwitzer clutches had the date stamped on the O.D. of the flange at the water pump end.

[Jonathan S.]

Re: Picture of a correct fan clutch for a '65 396/425

Wayne and John,

Thanks, this is just what I needed!

[Wayne M.]

Re: Picture of a correct fan clutch for a '65 396/425

............. (short shafts on big-blocks, longer shafts on small-blocks). Most Schwitzer clutches had the date stamped on the O.D. of the flange at the water pump end.

Here's an example of what John H. describes. Here's a small block Schweitzer clutch "CJ" ink stamp on the face; notice the stamping on the edge of the water pump flange 10.6.68.SC (Oct 6th 1968). Apparently, this stamping started sometime in calendar 1965.

Also, note the step in the diameter of the shaft, and the shaft is about 0.3" longer than the one on the big block "CK" shown in John's pic.

[Jim D.]

Re: Picture of a correct fan clutch for a '65 396/425

Here's a couple pics. of the Schwitzer clutch off my small block 65. Notice the date is stamped on the back side of the hub.

Jim

[David L.]

Re: Picture of a correct fan clutch for a '65 396/425

Jim,

I have probably seen about 50 or 60 Schwitzers fan-clutches in the last 30 years but never one that was date coded like yours. I learn something new every day. Does your 5-blade 17" fan (GM # 3872792, I assume) have a 2 1/8" pitch? The base 17 1/8" 5-blade fan (GM # 3770529) has a 1 5/8" pitch.

Dave

[Jim D.]

Re: Picture of a correct fan clutch for a '65 396/425

Dave,

I took the clutch off the fan looking for a part number but found none. The front face of the fan has a stamped "H" and a light blue daub of paint and on the back side of the fan, there is a stamped "W". My best guess on diameter is 17". I hope this helps. The car is a 1 owner, never been touched original and all the numbers/date codes that I've checked are correct (even the vac. advance unit is original- the judging guide is wrong but that's another story).

UPDATE - I did some more investigative work and found the "H" & "W" stampings indicate fan #3770529 which is correct for my small block, non A/C car.

Jim

[David L.]

Re: Picture of a correct fan clutch for a '65 396/425

Jim,

None of the fans made by the Hayes-Albion compary have a part number or date code stamped on them. They all have the "H" stamping, many have the word "FRONT", and some have the "W" stamping on the back side.

To measure the diameter of a fan simply measure the distance from the center of the hub hole to the tip one of the blades. This would be the radius. Need I saw more?

To measure the pitch simply lay the fan on a flat table and measure the vertical distance from the table to the highest point on any blade. The 65 396 fan (GM # 3872792) should have a 2 1/8" pitch. The base midyear fan (GM # 3770529) has a 1 5/8" pitch.

Dave

[Jim D.]

Re: Picture of a correct fan clutch for a '65 396/425

David,

Using digital equipment and using "R squared", the diameter is 17 1/8. The actual pitch is 1 3/4" on all blades. I believe this is a "base" fan which would be correct for my car.

Jim

[David L.]

Re: Picture of a correct fan clutch for a '65 396/425

Jim,
Your fan is GM # 3770529, the base fan. I didn't really read your first post with the clutch-fan picture careful enough. Apparently my eye caught the title "Picture of a correct fan clutch for a '65 396/425" in bold letters along with your pictures. I think it was a "senior" moment.
Dave

[Wayne M.]

Re: Picture of a correct fan clutch for a '65 396/425

Jim,

None of the fans made by the Hayes-Albion compary have a part number or date code stamped on them. They all have the "H" stamping, many have the word "FRONT", and some have the "W" stamping on the back side....

what about this one ?

[David L.]

Re: Picture of a correct fan clutch for a '65 396/425

Wayne,

Your Hayes-Albion fan stamped "66" is GM # 3888366 used on 66-67 427 Corvettes and 68-70 Corvettes (350 eng. wo/AC) The pitch should measure about 2 1/4" and diameter is 17 1/2" dia.

The "66" is the middle 2-digits of the 6-digit Hayes-Albion part number, NOT the last 2 digits of the GM part number.

I have at least 15 or 20 Hayes-Albion fans. Some of the Hayes-Albion fans have a 2-digit code. Example, the Hayes-Albion 7-blade fan used on the "late" 69 Z28's (w/2 1/4" pitch) has the number "94" (Hayes-Albion # 159432 and is GM # 3956684).
The "early" Hayes-Albion 69 Z28 fans (w/2" pitch) were usually stamped "84" but some do not have any 2-digit stamp.

I once owned a NOS 65-71 Chevrolet truck fan, GM # 3883159 (Hayes-Albion # 148932) that was stamped "H", "FRONT", "89" and "W" on the back side. It had 5 steel blades, 3 1/4" BC, 2 5/8" hub holes, 5 rivets/blade, and with a 2 1/8" pitch. I sold it as a "suitable substitute" for the extremely rare 67-68 Z28 fan (18", 3 1/4" BC, 2 5/8" hub hole, 4 rivets/blade, 1 5/8" pitch).

The dated fans w/ part numbers were made by the Schwitzer company.

Dave

[Ronald L.]

Re: Picture of a correct fan clutch for a '65 396/425

David, I agree that this is correct for 66, but question how the 17 1/2 is arrived at if that is how the fan is going to be described.

I have seen the prior posts...this fan is a tight fit, and is smaller than what is 'sold' as a reproduction that most call a 17 1/2" fan...

[David L.]

Re: Picture of a correct fan clutch for a '65 396/425

Ronald,
I have owned at least a dozen of these Hayes-Albion fans stamped "66" in the last 30 years and they all measured 17 1/2" in dia. (actually 8 3/4" radius from the center of the hub hole to the tip of one of the blades).
Refer to Noland Adams 63-67 book, page 426, lower left shop drawing, 17.50 DIAMETER. You will probably need a magnifying glass to read it.
I do not understand what you mean by "this fan is a tight fit". The 66-67 Corvettes w/AC use a 18" dia. 5-blade fan (GM # 3789562 or 3863137).
I have absolutely no interest in reproduction parts.
Dave