67 Big Block Fan

[Ben C.]

Good afternoon all. I have a puzzling question regarding what I thought was a great find. I found a five blade five rivet fan(both sides of the rivets are flattened without any mushrooming), however the diameter measures
17-1/4". It does not measure 17" and does not measure 17-1/2". Other identifying marks is that it has a "W" on one side and an "H" on the other. Is this a big block or a small block fan ?????

Finally it had been chromed without a copper base. Some is pealing off, but 60-70% will not easily peal off. Any recommendations to safely remove the rest of the chrome? Sandblast? Week long alkaline stripping? Reverse electroplating?

Thanks,

Ben Czerniawski (20305)

[Joe L.]

Re: 67 Big Block Fan

Good afternoon all. I have a puzzling question regarding what I thought was a great find. I found a five blade five rivet fan(both sides of the rivets are flattened without any mushrooming), however the diameter measures
17-1/4". It does not measure 17" and does not measure 17-1/2". Other identifying marks is that it has a "W" on one side and an "H" on the other. Is this a big block or a small block fan ?????

Finally it had been chromed without a copper base. Some is pealing off, but 60-70% will not easily peal off. Any recommendations to safely remove the rest of the chrome? Sandblast? Week long alkaline stripping? Reverse electroplating?

Thanks,

Ben Czerniawski (20305)

Ben-----

I think you have a small block fan. It's probably GM #3770529 but it could be others, too. The fan you seek, GM #3888366, has "front" embossed on the hub section and, usually, "66" as well. Other fans may also have the "front" but only the 3888366 has the "66".

The 3888366 is quite difficult to locate. It was used only on Corvettes and only for the 1966-70 model years. It was discontinued in April, 1971 and replaced by the 7 blade GM #3955182. However, I believe it is now reproduced.

[Wayne M.]

Re: 67 Big Block Fan

... I have a puzzling question regarding what I thought was a great find. I found a five blade five rivet fan(both sides of the rivets are flattened without any mushrooming), however the diameter measures
17-1/4". It does not measure 17" and does not measure 17-1/2". Other identifying marks is that it has a "W" on one side and an "H" on the other. Is this a big block or a small block fan ?????

Ben Czerniawski (20305)

Ben -- does it look like in these pics ?
The "66" refers to the last 2 digits of the part # 3888366 which is called out as the 427 fan for all '66-7 and '68-70 (my book ends in '70) for BB without C60.

These are notoriously hard to measure diameter. Jack H. has a suggested method wherein you measure center hole (2_3/8") then from the edge of center hole to the tip of one blade (through the centerline of the rivets; 7_3/8" in this case), then double this and add to the center hole measure. This total, so measured, is 17.13", which is a long way from the parts catalog 17.5". Maybe I should'a measure a couple more blades and averaged .

[Ben C.]

Re: 67 Big Block Fan

Ben -- does it look like in these pics ?
The "66" refers to the last 2 digits of the part # 3888366 which is called out as the 427 fan for all '66-7 and '68-70 (my book ends in '70) for BB without C60.

These are notoriously hard to measure diameter. Jack H. has a suggested method wherein you measure center hole (2_3/8") then from the edge of center hole to the tip of one blade (through the centerline of the rivets; 7_3/8" in this case), then double this and add to the center hole measure. This total, so measured, is 17.13", which is a long way from the parts catalog 17.5". Maybe I should'a measure a couple more blades and averaged .

Wayne, it looks exactly like these pictures but no "66" and no "front". I measured it and it is exactly as you measured 17.125! I do have 400 h.p. C60 option, however. Any additional comments will be appreciated.

[Ben C.]

Re: 67 Big Block Fan

Joe , Wayne Midkiff sends pictures and measurements. Mine looks exactly the same and measures "17.13" as he directs, which is also his exact measurement. Mine does not have either "#" or "FRONT". What do you think?

Also my car does have C 60 option. Any other comments?

Thanks

Ben.

[Joe L.]

Re: 67 Big Block Fan

Joe , Wayne Midkiff sends pictures and measurements. Mine looks exactly the same and measures "17.13" as he directs, which is also his exact measurement. Mine does not have either "#" or "FRONT". What do you think?

Also my car does have C 60 option. Any other comments?

Thanks

Ben.

Ben-----


There are other fans which APPEAR pretty much like the 3888366. The difference is the BLADE PITCH. It's usually pretty hard to discern one from another unless you have both and compare them very carefully.

I have never seen a known 3888366 that did not have the word "front" stamped on it. Most that I've seen also have the "66".

There are definitely other fans that have only the "H" on them. The "W" is a manufacturer's ID mark and will appear on any fan manufactured by the company denoted.

[Ben C.]

Re: 67 Big Block Fan

Wayne, would you be so kind as to provide a picture of the "66" fan "end on". By this I mean a picture in the long axis of the fan viewing one blade in cross section so that I can see the Pitch of the fan blade as compared tp the fan center. Joe Lucia, who is probably correct, feels my pitch is not the same. I may have a lower pitch fan blade.

Thanks.

Ben Czerniawski

[Ben C.]

Re: 67 Big Block Fan

Joe,

I did ask Wayne to provide me with one more picture being "end on" demonstrating the blade pitch. A photo of one blade in cross section as compared to the fan base should give me the pitch that I need to compare. I have a gut felling that my pitch is lower or at least incorrect as you have proposed. If I do get to compare I will inform you of the results.

As always, thanks for your expertise.

Ben Czerniawski. (20305)

[Wayne M.]

Re: 67 Big Block Fan

Joe,

I did ask Wayne to provide me with one more picture being "end on" demonstrating the blade pitch. A photo of one blade in cross section as compared to the fan base should give me the pitch that I need to compare. I have a gut felling that my pitch is lower or at least incorrect as you have proposed. If I do get to compare I will inform you of the results.
Ben Czerniawski. (20305)

Here it is, Ben

top fan is the "66" BB one of the previous post. The bottom one is the '63-5 327 fan for all except C60. #3770529. Just measured the "529" using the same method proscribed above; get 17.25" diameter, versus GM Parts & Accessories Catalog spec of 17_1/8" (go figure with these diameters ) The bottom fan has the round head rivets as it was from a '64 L76. You can see the greater angle on the BB blades.

[Ben C.]

Re: 67 Big Block Fan

Wayne, great photos. I have an excellent small block fan blade to swap for a big block. Must have correct rivets and steep blade pitch!!!!!

Thanks,

Ben Czerniawski (20305)

[Ben C.]

Re: 67 Big Block Fan

Joe, I have a small block fan blade in excellent condition to swap for a big block fan blade with correct rivets and PITCH!!!!!

Thanks,

Ben Czerniawski (20305)

[Joe L.]

Re: 67 Big Block Fan

Joe, I have a small block fan blade in excellent condition to swap for a big block fan blade with correct rivets and PITCH!!!!!

Thanks,

Ben Czerniawski (20305)

Ben-----


I doubt that you'll get too many takers on a trade. The small block fan, especially if you have the 3770529 as I suspect, are quite common. In fact, it was available from GM until not too long ago.

The 3888366 is quite difficult too find.