Camaro Research Group Discussion > Originality
772 fans and unstamped fans
67 kemie ss:
According to what I have read, there were two types of fans produced in 69 - the 772 stamped fan and the unstamped variety. According to Jerry's 69Z book, the unstamped was far more common, while Kurt's CRG report states:
•There were two versions of an 'unstamped' fan made by Hayes-Albion. 3947838 was the earlier 2" pitch version and 3956684 was the later 2.25" pitch version.
I interpret these comments to mean that the unstamped fan was available throughout the 69 production year such that a 69Z could have had either - and would most likely have an unstamped fan. Is this correct? The reason I ask is that I hear again and again from restorers (and HBC included) that the unstamped fan was an 'early' fan and that the dated 772 was used almost exclusively later in the production year.
OK, to be even more specific, would a 5C car have an unstamped 2.25" pitch fan?!
Thanks!
z28z11:
My 01C X77 original is unstamped, while my 03D Z11 original is a 772. I thought I read a long time back that the BB cars usually came with a 772, but I'll have to go read up on that from Jerry's Definitive book before casting that statement in stone (I have an unstamped fan for my 12A L78).
Regards,
Steve
z28z11:
The following is an even better answer from the Archives:
In 1969, the clutched fan changed to a seven-blade design (still 18 inches in diameter) with aluminum fan blades. Cars with AC or K02 received the same fans as the 1969 Z28 and L78/COPO cars. There were two manufacturers of this fan and a mid-year fan pitch change (2 to 2.25"), yielding four variants of this fan.
•The 3937779 fan had a 2" pitch and was made by Schwitzer. It was used early in the 69 production year (until approximately November of 68) and has the part number and month / year stamped on the fan blades.
•The 3947772 fan replaced the 779 fan and had a 2.25" pitch. It was produced by Schwitzer and was used during the remainder of the production year (and through the early 70's) and has the part number and month / year stamped on the fan blades.
•There were two versions of an 'unstamped' fan made by Hayes-Albion. 3947838 was the earlier 2" pitch version and 3956684 was the later 2.25" pitch version. The fans are normally stamped H and FRONT, but no part numbers or dates are stamped on the fans. They are similar to the 772 and 779 fans but with minor design differences (specifically: the design of the center section and details of fan blade rivet attachment).
From what has been observed on original cars, the 3947772 fan and the unstamped fan were used interchangeably and with approximately equal usage. As noted above, the 3937779 fan was only used on early 69 cars.
I guess my unstamped fan for the BB is likely O.K. - now I've got to go dig it out and determine if it's a Hayes or a Switzer, and the pitch.
KurtS:
That's directly from http://www.camaros.org/coolingsystems.shtml#fan
Not sure what to add. That pretty much tells it all.
69Z28-RS:
Steve,
The way I read that section on 1969 7-blade fans, ALL of the switzer supplied fans have the PN/date stamped on the blades, and NONE of the hayes-albion fans have the stamped PN, so the existence of the PN stamp establishes which company supplied the fan, and this is true for either the early pitch or later pitch fans from either company. My original fan is the 772 fan (stamped and dated) which should then be a switzer. A year or two ago I bought an unstamped unit at Carlisle which should be an Hayes-Albion. I should do a comparison of the two to see/notate the design differences. The most interesting aspect of that discussion, which taught me my 'new fact for the day' was the change in pitch mid-year. Obviously the earlier fans of either company would load the engine less (2" pitch) AND provide a bit less air thru the radiator (less cooling), so they apparently believed they had 'cooling issues' and redesigned the fan pitch for more air (to cool more), but also more HP loss.
Note: Kinda makes me think the earlier '69 Z28's might have been a bit faster than later ones given the changes thru the year (fan pitch, additional exhaust restriction on later cars with resonators, etc)... Was there a period of time between when Z28's had the earlier fan pitch, but transverse muffler (w/o resonators)?? :) Those cars should have been a bit faster right out of the factory.. :)
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