I have a 66 300HP with factory air and a 5 blade fan. My 66 AIM C60/C2 lists 2 fans; 3789562 (5 blade)and an opt fan (part# not legible). Can someone advise the 7 blade number. Is the 5 blade correct for a 4 sp and 3.36 rear? I am contemplating a 7 blade fan upgrade to hopefully improve the AC efficiency after a recent R134 conversion.
-
-
Re: C2 7 blade fan
For what its worth, here's what Noland Adams has to say on the subject of C60 equipped '66 cars:
"The fan blade assembly with C60 was part number 3789562, with an optional fan blade assembly, part number 3863137. In this case optional meant the assembly line was it install whichever fan blade assembly Chevrolet purchasing was able to furnish to the assembly plant. The fan blade assemblies both had five blades, yet each was quite different and they are easily distinguished from each other."
If factory concours is your objective, you might NOT want to go source a 7-blade fan because most all of these were dated on one or more of the blades. That complicates finding/getting a 'correct' part for your car.... -
Re: C2 7 blade fan
Randy------
The "optional" 1966 fan blade for A/C cars was GM #3863137. This was a 5 blade fan of 18" OD and 34 degree blade pitch. It contained no stamped-on part number. It was never available as a SERVICE part. The other fan used in 1966 PRODUCTION for A/C cars was GM #3789562. This is also a 5 blade fan of 18" diameter. It's overall configuration was a bit different, though, and its blade pitch was 28 degrees. This fan is usually marked with an "H", but usually no part number is present. This blade assembly was once available in SERVICE.
Curiously, although the 3789562 was once available in SERVICE, it was never catalogued as the SERVICE replacement for 1966 Corvette A/C applications; as far as SERVICE was concerned, it was specified as the unit for use on 63-64 Corvettes with A/C. For 1966 A/C applications, the SERVICE fan blade assembly specified from the very outset was GM #3853943. This fan blade was, supposedly, the 64-65 PRODUCTION fan blade assembly for A/C cars. I don't think that it was ever actually used, though, in PRODUCTION for those years. The GM #3853943 was a 7 blade fan of 18" OD. It was discontinued over 20 years ago and replaced by GM #3931003 which was of a more-or-less similar configuration. That fan blade assembly is also now discontinued.
If you wish to use a 7 blade fan assembly, I think that the GM #3955182 will work for you. This is a 7 blade fan of 17-1/2" OD. It's still available from GM for about 125 bucks, list.In Appreciation of John HinckleyComment
-
Re: C2 7 blade fan
Joe and Jack,
Thanks for the detailed responses. Both fans are 5 blade! As the JG says all ac cars are 7 blade I assumed the optional fan number was a 7 blade. I don't judge my car but do like to comply with the guide where possible. I had asssumed I had the wrong fan as there are errors in the AIM also.
Is it a logical assumption that a 7 blade fan will move more air across the condensor/radiator.Comment
-
Re: C2 7 blade fan
Randy-----
I don't rule out the possibility that the 7 blade GM #3853943 was used on some 1966 cars with A/C. "Officially", though, it was not. The 2 fan blades "officially" used in PRODUCTION for 1966 A/C Corvettes were BOTH 5 blade fans.
A 7 blade fan of the SAME DIAMETER AND BLADE PITCH as another 5 blade fan will move more air. However, I don't think that it will move proportionately more air (i.e. it won't move ~40% more air).In Appreciation of John HinckleyComment
-
Re: C2 7 blade fan
Randy - For better or for worse, the '66 Corvette TIM&JG (Judging Manual) is in err. There is a team reviewing and recommending revisions to the TIM&JG and I know the section on fan blade assemblies is a candidate for revision. Anyway, both Jack and Joe have provided an excellent analysis of the situation which is supported in the C60 section of the AIM. Both the fans listed in the AIM for the small block C60 RPO, i.e. the "usual" on and the "opt." are 5 blades and 18' in dia. BTW, the BIG BLOCK fan blade assembly for C60 and non-C60 is 5 blades and 17-1/2" in dia., i.e. there is no fan blade assembly change with the C60 RPO for BIG BLOCKs. If you would like pictures of the two small block C60 fan blade assemblies, let me know and I'll send some to you. PeteComment
Comment