Author Topic: CRG Report on Fan Blades question  (Read 6710 times)

Higgi 67

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CRG Report on Fan Blades question
« on: October 21, 2018, 04:15:25 PM »
If I was physically able I would be pulling my hair out!…   Because of my disability I am forced to depend on internet documentation (photos, part numbers, parts suppliers, etc.)   for all of my part purchase guidance.    Then I have to bother friends to come do my wrenching.  I keep getting burned and wasting other peoples time and my money I don’t have.   

[NOTE: THIS IS NOT MEANT TO BE A BLAMING STATEMENT/ TONE] I want to be able to turn to the CRG site / reports as the final say, but even something as basic as the correct 4 Blade Engine Cooling Fan report is throwing me a curve.  Should be simple….,  Correct 67 fan for my car = part number #3839282 and spacer #3814241. My dilemma is this,  the photo in the CRG Report (cooling systems - fan blades) shows the strengthening ribs running continuous through the centering hole.  The spacer and fan blade don't appear to be compatible... I can find multiple examples of the centering nub on the spacer is not very tall / pronounced (which matches my memory from 34 years ago  for what that is worth).  There is even an eBay listing of a NOS #3814241 spacer right now with the short nub (see included pic) .

The CRG Report shows 2 spacers below the 67-68 fan photo.   The one on the left #3876828 is most like #3814241 (which makes sense since I think both are to interface with the same 4 blade fan).    But the offset surface of the ribbed center is too deep to engage that short nub.   The taller nub on the #3927792 spacer for 69 would work,  but that spacer itself is not the necessary thickness.

The stamping off-set of the ribs raises the centering hole away from the mating / contact plane of the 4 hole pattern surface necessitating a taller centering nub on the end of the spacer…   I have seen multiple examples of 4 blade fans that claim to also be part number #3839282 that the reinforcement ribs do NOT continue through the center.  There are truck fans #3881239 that include a third piece/flat plate with centering hole riveted to the assembly on the spacer side to aid the centering, but passenger car fans do not seem to include this added plate [not to mention the tolerance variation introduced by the third part in the assembly is not a good thing with higher rpm engines]. Also,  the 4 attachment bolts have too much clearance to depend on them to center the assembly (water pump bearing would not last long with the fan weight not centered).

WHAT IS THE CORRECT FAN?   With or Without formed ribs passing through the center? CRG photo shows ribs thru,    I don’t want to waste more money/ buy one type of fan and need to get another spacer.    But I want to have the factory match that came on my car (and I threw out as as a teenager in favor of a light weight fiberglass performance fan…).   This shouldn’t be that complicated, but everything I try to do seems to snowball into confusion these days.

bcmiller

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Re: CRG Report on Fan Blades question
« Reply #1 on: October 22, 2018, 03:56:56 PM »
I do not have a quick answer for you, but bumping the post so it is seen in the Today's Posts
Bryon / 1968 Camaro SS 396 coupe - now old school 468 big block
1967 Camaro RS/SS 396 coupe L35/M40 - 4 generation family project
Looking for 68 Camaro with body # NOR 181016

67 RS Ragtop

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Re: CRG Report on Fan Blades question
« Reply #2 on: October 22, 2018, 04:37:09 PM »
FWIW, I own an early production 67 (10B, Los. production) Convertible, and the 327 in it has the spacer you show, but the fan is not as shown at CRG. My fan does not have the continuous ridges, and they stop short of the pilot hole as your second picture shows. The fan appears to be the original one that came with the car, but as usual, things could have been replaced over its "life". Just an old guy talking, but I seem to remember that style fan on earlier production vehicles.

Mike S

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Re: CRG Report on Fan Blades question
« Reply #3 on: October 22, 2018, 06:01:10 PM »
 I check both my 67 L35's with original 4-blade 'production' fan and they look like the 'Ribs not thru centering' photo. Plus, they have the L35 specific 3857042 spacer and the center tip is flush with the fan when mounted even the 67 AIM shows the centers not connected.
Note; the fan does have the thin reinforcement spacer behind the pulley.
  What motor are you looking to put this on?

Mike
« Last Edit: October 22, 2018, 06:42:00 PM by Mike S »
67 04B LOS SS/RS L35 Hardtop - Original w/UOIT
67 05B NOR SS/RS L35 Convertible - Restored

Higgi 67

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Re: CRG Report on Fan Blades question
« Reply #4 on: October 22, 2018, 07:02:52 PM »
Thank you for the replies!     My car is an L30 "MK"  engine (275 hp, 327 cu in)

Based on the responses I suspect that the non-continuous design was used.  Late last night I found example pics online (attached) of an 1 15/16"  spacer with taller centering nub that looks like it would work with the continuous rib design...

Once assembled I suppose nobody would know the difference, but now actually 35 years later I'm disappointed with my teenage decisions (throwing stuff out).  Fortunately I did have my father's guidance that kept me from throwing away the original intake/Quadrajet carb when I put on the aluminum intake/Holley carb.  That Holley never did run right (pops & bangs on decal) no matter how many jet changes I tried.   But that was "water over the dam" a year later when I put the original carb/intake back on and it ran great.

Anyhow,  my frustration on this is lessened as I believe your cars (vs. report pic) represent the actual production parts referenced with the spacer in the report.    Again,  Thank you very much!

67 RS Ragtop

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Re: CRG Report on Fan Blades question
« Reply #5 on: October 22, 2018, 10:19:09 PM »
My original spacer looks like the one in your first post (much beefier), and it to is flush with the fan blade when assembled. I also have the reinforcement plate that is installed behind the pulley - forgot to mention mine is also an L30.

KurtS

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Re: CRG Report on Fan Blades question
« Reply #6 on: October 24, 2018, 06:01:21 AM »
The caption for the fan picture is clear: 1969 four-bladed fan (hover over the picture). It's not a 67 part. It is an original 69 part - I took it off an original 69.
The write-up also explains that there were 3 different fixed blade fans. Expecting the 1 picture to the correct one for your car is 'misguided', imo.
« Last Edit: October 26, 2018, 05:26:32 AM by KurtS »
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bcmiller

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Re: CRG Report on Fan Blades question
« Reply #7 on: October 24, 2018, 01:23:47 PM »
Kurt, hovering over the picture does not work for seeing the caption on my phone. The label on the pic says 67 to 69. Just being honest, I think we could make it more clear.  We could add a pic or two.
« Last Edit: October 24, 2018, 03:33:27 PM by bcmiller »
Bryon / 1968 Camaro SS 396 coupe - now old school 468 big block
1967 Camaro RS/SS 396 coupe L35/M40 - 4 generation family project
Looking for 68 Camaro with body # NOR 181016

Mike S

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Re: CRG Report on Fan Blades question
« Reply #8 on: October 24, 2018, 04:16:33 PM »
If you don't have a 67 fan then I can take a picture of mine.

Mike
67 04B LOS SS/RS L35 Hardtop - Original w/UOIT
67 05B NOR SS/RS L35 Convertible - Restored

bcmiller

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Re: CRG Report on Fan Blades question
« Reply #9 on: October 24, 2018, 08:26:33 PM »
Thanks for the offer Mike, we are working on getting a good pic. Will let you know if we need one from your car.  Ed has a couple of pics.
Bryon / 1968 Camaro SS 396 coupe - now old school 468 big block
1967 Camaro RS/SS 396 coupe L35/M40 - 4 generation family project
Looking for 68 Camaro with body # NOR 181016

KurtS

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Re: CRG Report on Fan Blades question
« Reply #10 on: October 26, 2018, 05:29:37 AM »
Kurt S
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bcmiller

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Re: CRG Report on Fan Blades question
« Reply #11 on: October 26, 2018, 05:21:38 PM »
Thanks Kurt!!!  :)
Bryon / 1968 Camaro SS 396 coupe - now old school 468 big block
1967 Camaro RS/SS 396 coupe L35/M40 - 4 generation family project
Looking for 68 Camaro with body # NOR 181016

Mike S

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Re: CRG Report on Fan Blades question
« Reply #12 on: October 26, 2018, 05:38:04 PM »
 I am so curious why the 5-blade fan layout looks the way it does. Logic would make me think the blades should be evenly spaced around the hub.

Mike
67 04B LOS SS/RS L35 Hardtop - Original w/UOIT
67 05B NOR SS/RS L35 Convertible - Restored

bertfam

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Re: CRG Report on Fan Blades question
« Reply #13 on: October 26, 2018, 06:24:17 PM »
Quote
I am so curious why the 5-blade fan layout looks the way it does. Logic would make me think the blades should be evenly spaced around the hub.

Nope. And not just the 5 blade fan. This was done on purpose to keep the noise from the fan as quite as possible. They would make an AWFUL racket if they were concentric.

Ed

KurtS

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Re: CRG Report on Fan Blades question
« Reply #14 on: October 26, 2018, 06:42:03 PM »
Noise.
Evenly spaced would howl at a frequency of 5 times engine speed. They stagger them so there's no one dominant frequency. Same with the alternator fan.
Even the simple fixed fan doesn't have the blades at 90 degrees to each other.
Kurt S
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