Could anyone please help me out? What fan do I have to use - will say what diameter and how many blades - for my 68 400cci (YS coded) without AC? The car has a correct 4bbl quadrajet and power steering (if this should be of concern) and I´m using the correct GM fan shroud (and a non-stock but exact fitting RodneyRed radiator). Driving a car without AC I already was told NOT to use a fan clutch.

Concerning the fan shroud I think it should be a 19" fan, correct? So I only have to know how many blades... And where to get it...

YearOne and ClassicIndustries are selling 6-blade Flex-a-lite OEM fans, both times showing the same picture. But Year One (# FA24) is telling they are an upgrade for direct-drive 4-blade fans, Classic Industries (#FL5719) is talking about using them together with a fan clutch... And Ames (# FP191HA) is showing exactly the same pic, too, labeling it for use w/o clutch but is selling it twice as expensive as the other two suppliers (USD 69.00 vs. 34.95)...

Any input would be appreciated!

Thanks and best regards

Thomas

PS: Will I need a fan spacer, too? And if so what length should it show (GM offered 1 1/2", 1 15/16" and 2 9/32", only the first is available at Ames)?

I would assume that you are looking for a fan similar to the one I have, a five blade 19" flex fan. As for the spacer, I can check the length for you later today.

Pic:
http://www.frojdh.com/bilder/main.php/view/bird/underhood/enginebay/flexfan_oem.jpg

SnowCruiser,

thanks for the pic. One question remains: I was told the fan (regardless how many blades) should be half in, half out of the fan shroud. On your picture it´s comletely out and at the same time your fan spacer seems to be the largest one possible... Does your fan provide your car with optimal cooling?

Cheers

Thomas

The fan spacer is 2", and as far as I know it's been on the engine throughout its existence. As for optimal cooling, I've had no overheating problems with the setup. Even in heavy traffic on a day like this (+30C) the needle just barely goes past the middle marking on the rally gauges, which I assume is about 210F.

The fan actually sits about 1/2" into the shroud, although fromn the angle the pic is taken it doesn't show very well.

Like Snow Cruiser, my original fan sits about a half inch into the shroud. It is the AC flexfan, however and has no spacers.

With a little more battle wear in the ompartment, here's my w/o a/c flex fan with factory spacer, measureing about 2.5".

My 7 blade 19 1/2" factory w A/C clutch fan rides half-in, half-out. No spacer.

http://pg.photos.yahoo.com/ph/v_papesh/detail?.dir=/e852&.dnm=7a53re2.jpg&.src=ph

Vikki, do you have the long or short hub water pump on your car? I know that the 4 1/2 pump was introduced somewere in the production year (possibly to improve cooling).

Water pump is 4 1/2" from back of casting to front of fan hub; fan is dated J68 and is 9796134, and fan has 1" clearance to shroud.

My car is a 4th week Nov 68 build.

Service parts found here: http://thefirstgensite.com/library/fbillustrated/group01/GR01_Num.pdf

Of the two pictures posted here we obviously have a clutch type fan on Jim's sweet '68 A/C car (with an A/C belt issue?)
and Amervo's direct driven FLEX fan. There is also
a direct drive rigid fan that the fins don't flatten at rpm. This would be the type I use myself. I started with a two inch spacer and have played around with that. Right now I've got a 1.5" spacer and it pulls quite a lot of air like that.

I think my 68 400 w/o A/C came with a clutch fan. I am putting one on. Does this help or is a flex fan better?

Greg, what are you noticing with the "(with an A/C belt issue?)" comment?

My car, produced second week of December 1968 at the Lordstown plant, uses the short hub (4") water pump. Although the pump has been exchanged several times over the years, I am pretty sure that the pulleys, brackets etc are originals. Even if the long nose pump was introduced around mid 69, it seems that there were old pumps still being used at the assembly line.

As for the clutch fan vs flex fan efficiency, I've tried both and my personal experince (which is not by any means scientifically proven...) is that the flex fan performs better at idle or in traffic, clutch fan keeps engine cooler at highway speeds.

Jimc,
It is probably just the angle or the way the light was hitting it, but it looked to me as if it may be starting to frey a little on the edges, and the alignment off just a tidge. It all looks to be so very pristine everywhere else that
the belt looked "out of place". Lookin' at my stuff I shouldn't be one to talk. Another bad habit.
Now that is a rigid fan though isn't it?

Greg,
I wondered if you might be referring to the threads loose on it. Although the belts are all only a few hundred miles old, that AC belt does look rough. I purchased all repro belts with correct look and part numbers from Quanta and have wondered about the look of that belt.

The alignment was just a camera angle illusion in the other picture. It is straight.



I’ve been confused on terminology of fans used here. I have always called mine the flex fan because it is what my original window sticker calls it. The clutch was replaced in June ’75 when I got some AC stuff fixed but I don’t recall nor have receipts that show the replacement of the fan.

I figgerd as much, I mean it just had to be. And PLEASE don't think it was a dig, 'cause it sure wasn't.
As the fan option is plainly read on the sticker, we might open that for discussion too. Just to be sure I don't confuse the masses. I can't afford to loose more stars! What I truely wonder is if the FLEX has to do with the energy behind it. Seeing as how it is a clutch type fan, it COULD stand to reason the term comes from the different levels of torque at different temperature ranges (on a thermostatic clutch) or engine speeds (with a centrifugal clutch).

Greg, I never thought your comment was a dig. Actually I look for comments so that I can make future improvements. This old guy trys to learn something new every day. This site helps with that objective. You wouldn't believe how many things that I have changed or improved though comments here. In fact right now I'm mulling over a move of the emissions sticker on mine. But that is a long story.

Somewhere I read that the clutch in mine may be wax? Anyone know if that is true and how it works?

I have not disassembled mine, but other clutch fans I have seen have used silicone fluid and/or a bimetal spring to control engagement.

Some are temperature-engaged (turn faster with hot engine), others engine speed engaged (turn faster when engine is running slower, spins freely at highway speed to conserve horsepower and reduce noise) similar to the way the blades on a flex fan flatten at high speed.

The Vikkster has it down, but you wont have to disassemble to decide which you've got.
As I have seen, original equipment IS the thermal clutch that has a bi-metal, coiled spring on the front of it. The centrifugal does not have the spring, and uses a viscous fluid coupling that allows it to 'freewheel' at engine speed. The thinking is that at higher speed you are getting the primary air flow from driving.
When replacing you most usually have an option and the thermostatic IS less expensive.

Thanks Vikki and Greg.
Also, I’ve done some research and may have found, what might be, an explanation of the “Power Flex Fan” on my sticker vs. the definition here that doesn’t seem to match my fan type. According to the AMA specs and parts book there were six fans used in ’68.

9794230 4 blade 17 5/8 dia. F/6 exc AC or HD
9798940 4 blade 19” dia F/8 exc AC, AIR or HD, also- F/8 400 RA, also F/8 AT 2bbl exc AC,

480033 5 blade 19” dia F8 400 4bbl exc AC HD or RA

9788982 7 blade 18” dia F/6 AC or HD

9796372 7 blade 19 ½ dia F/8 AC *
9777012 7 blade 19 ½ dia thermo cont All V8 exc AC *
* I believe the parts book was wrong in which of these fans had the thermostatic control since the AMA specs show that the V8s with AC got it rather than the other way around.

Back to the “Power Flex Fan” on my sticker. It appears that a 19” 5 blade Power Flex fan is selected for the 400 and 400HO engine options to replace the standard 19” 4 blade fan. Thus, that is why it appears on the sticker. However, the AC option later substitutes another fan, a 7 blade, 19 ½” thermostatically controlled part. The AC option on the sticker simply does not spell out the new fan, which trumped the 400HO option.

This old guy learns something every day.

And this is most certainly the place to share that information. Us young pups (just short of 50) appreciate that.

This is good info here.

Does anyone have an extra good clutch fan?

I had documented the fan and some other package detail on my car's page a few years back. http://www.abilitypc.com/photos/firebird/

I haven't updated it, and it does not contain part numbers, so I should make a comprehensive chart for the site. Thanks for the '68 info, I have the '69 and '67 info and will put this together when I have a few minutes.

If you buy a used fan with a silicone clutch, try to buy it right off the car or engine. If it's been sitting flat on a bench or shelf for a long while the silicone can seep into the bearing area. Vertically stored with no sign of residue, moisture, rust or damp dust should be okay too. Best bet would be to put a new clutch on a new or used fan, and be sure to check any used fan for straightness as well. A glass tabletop or granite countertop is a good surface, all blades should touch the surface at the same time. Vibration from a bent fan will quickly destroy your water pump bearings.

This is REALLY good info here! :-)

So, now I know
- that I will need a 19" dia 5 blade fan parts# 480033 without fan clutch (thanks to Jim)
- AND that the new 6-blade Flex-a-lite OEM fans sold by YearOne, ClassicIndustries and Ames aren´t OEM at all...

Does anyone know a source for these original 5 blade fans?

Thomas, also see the AMA specs posted at: http://www.firstgenfirebird.org/firebird/1968/ama/ama_page3.html#coolingsystem
Scroll down to the cooling system/fan information and see note "b".

“(b) 7 blade 19.5 dia. fan on all V-8 with A/C - 5 blade 19 dia. Power-Flex std. on 400 V-8 except std. 4 blade fan used with Ram Air Option.”

I have a spare 480033 400 non-AC Power-flex fan. It looks odd, but it's perfectly normal. The offset arms lower the noise level. The blades are riveted, with stiffeners, to the arms of the hub. The blades themselves are quite flexible.


I need to clean up the spacer to see if it is correct. You need a 2.5" spacer and 3 1/2" fan bolts to match, mine is about 2 9/32". This particular fan was mounted on a later model engine.

Vikki, what is the correct part # for the 69 flex fan? Mine doesn't look at all like that, the blades are less offset and are bolted instead of riveted.

nice floor

Vikki, by the looks of that fan, do you think the one I have is correct already? Here is a pic before I started tearing down.




According to my PHS, I should have a clutch fan. If this one is still a correct style unit, I may wait and find a clutch one in the future.

The fan in my photos is the 480033 Power-Flex, used on many non A/C applications.

Usage on '69 models (Firebird) is as follows:
4 blade 17 1/2" diameter: 6 cyl w/o A/C
4 blade 19" diameter, 2.3" pitch: 350 w/o A/C, Firebird 400 Ram Air
5 blade Power Flex 19" diameter: Firebird 400 exc. Ram Air, all 350 with Heavy Duty Power Flex Fan option
7 blade Power Flex 18" diameter: Firebird 6 cyl with A/C or Heavy Duty Power Flex Fan option
7 blade Power Flex 19 1/2" diamater: Firebird V-8 MT with A/C, Firebird 400 (exc. Ram Air) with Heavy Duty Power Flex Fan option, Firebird 400 AT except Ram Air with A/C and Heavy Duty Power Flex Fan option, all 350 with A/C and heavy duty Power Flex Fan option
7 blade Thermo Clutch 19 1/2" diameter: optional on all V-8 engines with or without A/C except Firebird V-8 (MT) and 350 H.O. when equipped with A/C

I would double check your PHS report with PHS. They will look it up again if you ask for verification. I had the previous owner's PHS for the Le Mans and I ordered one of my own; there was a discrepancy so I inquired and they confirmed the second one was correct. What is the fan code and description on your PHS?

I think the thermo clutch was standard with 400 with auto with A/C in '69 as well, rather than optional.

I have my PHS documents here at work and I think you may be onto something. The billing history and window sticker info do not coordinate on this issue. I'll try and contact Jim.

Thanks,

Tim