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How close is too close on fan?

68stang289

68stang289

Member
Problems, problems problems. I'm getting a little tired of issues with this car! I added power steering to my 70 428. After finding out that I was running a 69 block with a 67 style harmonic balancer, I was able to locate the correct 69-70 balancer to fit the 69/70 style 3 groove crankshaft pulley I got.

Now with all of that installed, I'm really tight on my clearance between the crankshaft pulley and the fan. I torqued the balancer down to spec, so I don't think it is an alignment issue with that. I'm running an aftermarket flexalite style fan with no shroud. I have an inch and a half spacer in place between the water pump pulley and the fan, with approximately one and a half inches from the fan to the radiator. I have, at most, an eighth of an inch of space between the crankshaft pulley and the tip of the fan blade. So thus my question...just how close is too close?

I was thinking I would just order the 2 inch fan spacer and run that. That would give me roughly 5/8" of clearance between the crankshaft pulley and the tip of the fan blade, and still give me an inch of clearance between the fan and the radiator. Thoughts before I burn this car to the ground?
 
Obviously since you have room between the fan and rad, you need a longer spacer to move the fan forward. Also, why not use a shroud?
 
"cmayna" said:
Also, why not use a shroud?
Click to expand...

The car did not have one when I got it. It's kind of one of those "I'd like to see the car up and running before I work on little issues like that" situations really.
 
Well since you are working on the fan location situation, I'd throw a shroud on there.
 
"cmayna" said:
Well since you are working on the fan location situation, I'd throw a shroud on there.
Click to expand...
:stu
Why remove the fan twice? Get the shroud and spacer and do them at the same time.
 
The fan is too close when it contacts the radiator...

Sorry...but it's true!
 
Wow, 5 replies and no answer! Bunch of post-count monkeys around here. . . :sarc

1-1/2" from the rad should be OK. But 1/8" from the crank pulley is too close. That fan will flex! Get that 2" spacer. An inch from the rad is fine

Robert
 
When the fan flexes it will increase the clearance because the fan would tend to flatten out. I don't recall the clearance between my fan and pulley but recall it being pretty tight.

You'll have to decide on a shroud before you can set the proper distance. The fan blades should be a little less than half way out of the shroud. I can tell you that my stroked Windsor heats up real fast without a shroud.

Anyway, if it clears the pulley when not running there is no reason it should not while its running.

Sent from my HTC Inspire 4G using Tapatalk 2
 
Here's a pic that may help and I think the flex fans blades have a lot more curve to them than the stock solid ones so that probably puts it closer to the crank than a stock one would be. At worst you could shave a 1/4" off the 2" spacer if need be.
radiatorfanandshroud.jpg


Jon
*Sent from my laptop using my spindley long fingers*
 
"66benchcoupe" said:
Wow, 5 replies and no answer! Bunch of post-count monkeys around here. . . :sarc

1-1/2" from the rad should be OK. But 1/8" from the crank pulley is too close. That fan will flex! Get that 2" spacer. An inch from the rad is fine

Robert
Click to expand...

Huh? Didn't my first reply basically say to move the fan forward?
 
"Sluggo" said:
When the fan flexes it will increase the clearance because the fan would tend to flatten out.
Click to expand...

True, but as the fan relaxes and returns energy, say upon decelleration, it will flex back beyond its original position and then settle. I've seen it. That's why I say 1/8" is too tight. I've actually seen old fiberglass flex fans flex towards the radiator and tearing them up.

Robert
 
"cmayna" said:
Huh? Didn't my first reply basically say to move the fan forward?
Click to expand...

Yeah, I guess it did. But I read it as "Hey, lets complicate the issue and throw a shroud into the mix."

So it goes. . .

Robert
 
Man, a guy goes out to get a beer (or 6) and this post blows up! Thanks for all of the info guys! I will definitely be replacing the 1 1/2" spacer with a 2" spacer to gain the extra clearance. The flex of the fan as the speed of the motor slows down is what had me concerned the most.

As far as cooling goes, I've never had an issue. The car runs at right around 180* the whole time she is running (that is, when she was running...6 years ago). And that's reading off of a good Autometer gauge, not the factory one.
 
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