1968 Distance of fan from radiator with shroud?

[jochlela]

I'm replacing the shroud for a 20" radiator after the shroud was damaged on the top by the fan. I thought someone may have leaned on the shroud when the car was in transit to Australia but when I removed the shroud I noticed the bottom of the shroud was cut up by the fan.

Looking where the shroud was cut it looks like the fan is sitting to far within the shroud. There is very little of the fan sitting outside of the shroud where based on other threads the fans should be half in and half out of the shroud.

My thoughts are to replace the fan spacer with 2 1/4 fan spacer. Currently, the four blade fan (17 1/8 diameter based on my measurement) is 1 inch from the radiator with a 2 3/4 fan spacer so the fan will be now 1 1/2 inch away from the radiator. Will the fan be too far?

It cost me $40 to buy a new shroud and the $65 dollars to send it to Aust (still cheaper than buying locally) so to me it makes sense to shorten the fan spacer so I don't shred $105. Of course, as long as I don't lose too much cooling from the fan it I move it away from the radiator.

Thanks in advance for the replies.

 

[dalorzo_f]

Sounds like you are talking about two issues:

1. depth of fan in shroud
2. offest and fan hitting shroud

On # 1

as noted half-and-half-is the "norm", depth of fan will make no major difference to clearance to shroud, as you are talking 1/2" or so at a minor deflection angle... (ok, as the motor mounts flex it will drift a bit). I'd think more in than out should be better, but in reality it probably make zero difference if its 1/2" either way for the most part... unless you just idle it in your garage, as once you get moving dynamic air flow takes over from the fan and static idle conditions (the reason most suggest 1/2 and 1/2, to improve flow at a standstill....)

On #2

Someone leaning on the car will move the body, not the fan in relation to the shroud (the fender-bone-connected-to-the crossmember-bone, the crossmember-bone-connected-to-the-radiator-bone, etc) It all moves together in that light.

Under stressed driving loads and dynamics it all changes... (imagine holding a spindle/brake/wheel and the impact load of hitting a pothole at 50mph and how fast it's moving the assembly)

Moving the fan forward or back with a spacer will not address item 2, which seems to be your concern. If that is the issue you want to address I'd look at worn motor mounts (or modified) and the mounting of the radiator, as the shroud attaches to it.

Or maybe the wrong shroud was used..

 

[jochlela]

Nice to hear from your Richard.

All way around the shroud where the shroud joins on to the radiator there is flat section about 3/4" to 1" but then on the top and bottom of the shroud it flares out to accommodate the fan. Since the depth of the fan is so deep it is has passed the flared section and up to the flat section. The idea with the shorter spaced is to reduce the depth of the spacer back to a better fit to the flared section.

I agree with you statement about leaning on the car but as the shroud is made out of plastic you can push it down so it gets out of shape.

Are you available this weekend to have look? I will drive the CS to your place.

Cheers,

John

 

[CougarCJ]

Sounds like you have a water pump that is offset from the original.

 

[Northern Pony]

Jochlela;
I had a similar situation with my plastic shroud, and am surprised your shroud was only cut by the fan and not shredded as mine was, my solution was a shorter spacer. I had the long spacer that you have 2 1/4 and went to 1 1/2. You need clearance all around the dia of the fan. As yours is mine was tighter to the shroud the closer the fan got to the rad, and my shroud was a bit out of round, (poor after market parts ). Ideally your fan functions best the closer to the rad as possible, when I went with the shorter spacer, I then switched to a five blade fan, then all was well.
Keep in mind that with reving the engine you will get movement of the engine and hence movement of the fan within the shroud. Likely the shroud was an add on as the car was running hot and it was not looked at close enough. I believe you will get by with more clearance on your existing set up.
BoB

 

[jochlela]

Thanks Bob.

To be more correct with my description, yes the top of the shroud was shredded. I fixed it by cutting some plastic to go over the whole and then using small bolts and nuts to keep the plastic in place. Finally, I put 100MPH tape over the plastic to stop air flow between the shroud and plastic. It looked ugle but no troubles with heating.

The other weekend I wanted to show the car properly by having the bonnet open as the former owner (Steve - the mechanical guy) has done such a great job with the engine bay. I could notice the car was running hotter than normal without the shroud.

Sounds like a shorter spacer is the way to go first. My current spacer is 2 3/4.

Cheers,

John

 

[dalorzo_f]

Drop me a PM if you want me to drop by.

Would need to see your setup to provide input, happy to take a look...