66-7 427 vs.'65 396 Fan Assemblies (diameter)

[Wayne M.]

Hate to stir up any controversy, but the fan that was and is on my late '65 L78, when I bought the car in 1988, [shown in thumbnail, hidden below the 2 auto-load pics] is only 17.04" in diameter (like that for a 396, rather than the 17.50" dia., which is on the GM drawing for the 3888366 '66-7 BB fan). Hope you can read these drawings at posted resolution. Notice last line on left bottom of '66-7 drawing reads "similar to 3872792". I take that to mean that (maybe ?) only the diameter has changed, indicated from the blade length of the '66-7 (5.93") being exactly 1/4" longer than that shown for the "792" dwg (5.68"). Other dimensions are essentially the same. All other stampings on my fan point to it being the '66-7 unit [FRONT, H, and 66, as well as W on backside of one spider].

Measurements taken in 2 stages; from edge of center hole to tip of blade, along centerline of rivets; then add 1/2 of dimension of center hole [2.377 to 2.380", painted, per dwg]; then multiply this radius by two for the diameter. (To Jack H.; all 5 blades were exactly same length).

Might add that my '65 car is so late that the next big block assembled in St. Louis was a 427, although the chances of its original fan surviving 23 years at the hands of various Bubbas is slim.

So .... what does the '66 TIM&JG say as to overall diameter; could my car have an early hybrid 3888366 fan with short blades like the 396 one ? And I'd like to shake the hand of any judge who can proclaim the difference between 17.0" and 17.5" overall dia., with the fan in place on the car .

1966-7 427 fan from Noland's Vol 2 page 415


1965 L78 fan from Noland's Vol 2 page 286

[Loren L.]

Re: 66-7 427 vs.'65 396 Fan Assemblies (diameter)

"And I'd like to shake the hand..."
No you wouldn't....just because your shaking hand would already be formed into a fist.....and deservedly so. I'm sure that the judge with the "measuring eye" would quickly tell you to "quit waving that blueprint in my face"; Old #23564 has been nothing but a trouble maker ever since it was found; but it does kinda disturb the advocates of "Chevrolet Was Restoring cars To Abolute perfection" creed when you point out that they couldn't even keep track of how many they had built......

[Keith B.]

Breakout your tape at Bowtie Check Off

How would you feel if your was car going for Bowtie check off and the judges were measuring your fan on the car with a tape measure and throwing it out because it was 1/8th inch off and had a "W" on it.

Gee that would never happen.... Wait it happened to me!!!!

[Ray G.]

Re: 66-7 427 vs.'65 396 Fan Assemblies (diameter)

Hello Wayne;

You've been involved longer than I have.

I have the utmost respect for the judges, having been on both sides.

But the judges who think they know the most and are the most positive about their comments aren't always correct, and are usually the most in need of Judging schools, seminars, and DVDs.

In the last few years bringing documentation pictures and prints as in your original posts seem to the best defense/offense on controversial subjects.

That's my 2 cents.
Hope it helps.
Ray

[Bill W.]

Re: 66-7 427 vs.'65 396 Fan Assemblies (diameter)

Ok Wayne heres another one for you to think about. My original blade from 17346 measures about 17" has a H and front stamped on one side & a W stamped on the other. my blade from 16120 has the W and has something on the front but is to rusty to read .It is the exact same measurments . BUT the blade from 17346 has flat headed rivits on the front side and 16120 has round head rivits on the front side. Maybe more than one supplier or running changes?.....Bill

[Bill W.]

Re: 66-7 427 vs.'65 396 Fan Assemblies (diameter)

hey Wayne where are you ?

[Wayne M.]

Re: 66-7 427 vs.'65 396 Fan Assemblies (diameter)

hey Wayne where are you ?

Sorry, Bill & others -- Am in the early stages of upgrading / building a new computer and am having to re-learn all the terms /options and decide which way to go .

Re your fan on # 16120; never seen the round rivet heads after '64 (but then I've not been out much ) Are the blade angles similar to # 17346 ? Is the "W" on the back of # 16120 ? I have a '64 SB 5-blade fan (3770529 ?), and it has round rivets but no back-side stamping on the spiders or hub. Maybe they did have more than one supplier, but this was certainly a low volume need for L78's.

On your # 17346; sounds like the 427 fan, except no "66" stamped on the front (which I believe is what one would expect on a 396).

I'd be curious to know if someone has measured 17.5 inches overall diameter using method [1/2 the center hole diameter plus the length of each blade from center hole edge to blade tip (all x 2)]. This challenge extends to those with the "66" stamped on the front, ie. those with 427's.
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Apology: didn't mean to criticize judging of this item, but merely to point out that it is quite difficult to measure the diameter of such an asymetric object, even on a work bench, and when separated from the clutch assembly.

[Tony S.]

Re: 66-7 427 vs.'65 396 Fan Assemblies (diameter)

Wayne. My car is 23340. My fan is 17" (I removed it and measured it). There is a "H" and "FRONT" on the front of the fan (covered by the fan clutch) and a "W" on the back (it's visible on the car). Each of the five blades are attached with 5 flat rivets.

Tony

[Bill W.]

Re: 66-7 427 vs.'65 396 Fan Assemblies (diameter)

H is on the front W on the back on 17346..16120 is so rusty I need to do some blasting. but yes all angles, shapes & measurements seem to be the same . Bill