I'm looking for some assistance with determining:

1) What is the proper distance between the fan clutch and radiator? How close can I get to the radiator without causing damage during normal operating conditions?

2) If I should have a fan spacer (Part # 535253) on the water pump shaft.

I have a 69 Firebird which according to PHS came from the factory with 400 and turbo 400 which cam run a little high temp from time to time (208-230). I do drive it to work everyday and sometimes hit traffic, so the Southern heat and humidity takes its toll on the car.

All the engine components are stock and doesn't appear to be missing anything (that I know of), so I am curious if it should have a fan spacer on there between the water pump and the fan.

I am currently running the original 7-blade factory fan (#9796134) with the factory water pump pulley (#367161BM). The car also has a brass 4-core radiator on it.

There appears to be some room (2-1/2") to draw the fan closer to the radiator. I want to make it right and do whatever I can to make the engine run cooler without making aftermarket modifications to it. Did the car came with the fan spacer (#525253), however this piece is also 2-1/2" in length. That of course makes me wonder if fan clutches vary in size and depth. Or, maybe the radiator is a replacement and also differs in size from the original 4-row one.

I would like any advice from anyone who has a 69 factory 400 and if you could tell me if the 400 Firebirds came with a fan spacer. Thanks in advance guys.

Does your car have or come with A/C? I could be wrong, but I am almost positive that the only firebirds with the thermostatic clutch where the ones that came with A/C, that along with the 7 blade 19.5 in fan. If no A/C, it should be a 5 blade 19 in fan (power flex) on 400 V8's. Also, you might want to ensure you have a good working rad cap that is a 14-17 PSI cap. This will help a good deal. I am also not sure about the 4 core, there has been some debate about them, but I know my 400 (A/C car) came with a 4 core, I cant remember the exact specs on it, but I think there were two different sizes of 4 cores, one being 23 inches long and the other 21 inches long. I know some came with a spacer, but I dont know exactly which ones, but I do know the 400's with A/C didnt. Hope this helps you out some.

Do you have a fan shroud? Seems to me the fan blades were about half way in the shroud. Half the blade tip inside and half out.

50% in ,50% outside...is correct

USMC Ordy,

Yes, my car is a factory 400 & factory A/C car. The original A/C was replaced with a vintage air system by previous owner.

I'll check on the radiator cap (14-17 psi) and acquire the correct or a better one. As far as the fan spacer though, you say yours, also a 69 with 400 & A/C didn't come with one.

I believe like other FGF viewers indicated is currently sitting at about 50% in the stroud and 50% out or there abouts. Just seemed like the extra space near the radiator could call for a fan spacer like the ones that Ames Performance sells. If I remember correctly, it comes in a 1", 1-1/2", 2", then amybe also a 2-1/2" spacer.

Thanks in advance for the help!

Hey Craig, yes, my car is an original factory 400 with A/C. I have removed the A/C out of it since it was all jacked when I bought the car and also plan on going with the vintage air. But, to answer your question, my set up didnt have a spacer and was in fact sitting about half in and half out of the shroud. I did though add a spacer to mine, 1/2 spacer if I remember correctly, to push it in towards the radiator more and now it sits about 3/4 in and about a 1/4 out. Thats a guess and about where it sits, but could be slightly more in then 3/4. I was also having high temps and over heat problems last summer. I ended up having to replace the radiator cause it looked pretty bad and I put a alum 3 core in it and also replaced the pump with a Flow Kooler water pump and put in a 160 thermostat and now I run about 180 -190 on 90degree+ days with 80-90% humidity. I also had tried, before changing out the pump and radiator, using a 160, 180, and 190 degree thermostat and the car would still over heat. Also take a look at this post Water Pump Mod. This will also help if your water pump divider gap has never been adjusted.

Not to hijack the thread, but my clutch fan only sits about a quarter of the way into my shroud. I was always under the impression that adding a spacer and extending the fan away from the water pump put more stress on the pump shaft and bearings.

Is that BS? How many are running spacers with no problems? I would like to get the fan further into the shroud to be more efficient.

Would positioning the fan deeper in the shroud make it more efficient? Maybe the design reason it is mostly outside the shroud so that it sucks air from the front and spin it off to both the open sides and back combined?

Not sure if it is BS or not, but I know some cars came with a spacer.

I don't think the fan would be more effective further into the shroud, seems logical that it would be, but I've read somewhere that it is more effective with the tips half way in. Maybe it spills air off the tips faster or something. FAQ at Flex-a-lite answers it should be as close to 50-50 as possible, doesn't say why though.

I also found a little more info on this and it would pretty much be as Bluebird said. I found the info HERE. The fan blades on the engine should sit half in the shroud and half out of the shroud. If your fan is all the way in the shroud or on the outside of the shroud it will not pull air through, and get rid of the air from the radiator area.

USMC Ordy,

That information does surely help me out. I will continue to run without one and just concentrate on other areas to cool the car down. Thanks a bunch.

Craig

Do most agree that even a car without A/C should have the fan blades sit half in and half out of the fan shroud for best efficiency? Had not heard that before and I know mine is much further inside the fan shroud.

I dont have A/C running in my car and I do have a 1 inch spacer and it sits about 80% in and 20% out and I have a new alum 3 core rad with a flow cooler water pump and it runs between 170-190 on 90 degree days with 80-90% humidity. I hadnt heard about the 50 50 thing until this post was started and I started looking into it. While most the looking around the internet seems to agree with keeping 50% of the fan in the shroud and 50% out, I couldnt tell you honestly if it would make a difference as i am happy with the temps I am curently running. I am contemplating pulling off the spacer to see what it does and if I do I will report it back here. Would be interesting to know if anyone has done both and if their temps got any better running the fan half in and half out.

Anybody ever try the waterless coolant from
evens. I hear it a little on the pricey side
but does it work?

I know there are a crapload of Engineers on this board so someone has to explain this half in half out concept. My Electrical Engineering side says, put the fan all the way in the shroud where the back side of the blade intersects the back side of the shroud. Someone please explain.

I guess you need to think outside the shroud...

Think about how a water pump impeller pushes water away from the middle (centrifugal force), your fan has some of the same effect and the forward part of the blade will tend to recirculate hot air inside of the shroud, I think... maybe...

Actually that does make a little sense. I am guessing the Pontiac Engineers empirically played around with it back in the day. Whatever produced the most air flow is what they went with.