Clutch fan, new shroud, doesn't fit!

[boatillo]

So I have a thermal clutch on my stang that was using a huge 5 blade fan with no shroud on a 4 core brass radiator. Decided to order a shroud one day because I heard that's the smart move - fan doesn't clear it (20" standard shroud fits the radiator fine). No problem, I'll buy a smaller clutch fan - but wait they don't make them in <17" sizes which is what I need to clear the bottom of the shroud (engine sits low, fan is not centered on radiator, thus the non-clearance on bottom when sides and top have 1" free).

Get out the angle-grinder and cut 0.75" off each blade on my 18" fan? Or is this a really bad idea...

I could change to a flex-fan, which they make in 16", and ditch the clutch. But I read nothing but bad stories about noise, broken blades cutting throats, and parasitic drag of up to 10 rwhp.

Or put the original fan back on without a shroud.

 

[2+2GT]

A 17" clutch fan should fit perfectly. Why did you get an 18"?

 

[Pony66]

If you cut on your fan, you will likely unbalance it and kill your waterpump.
There are 17" clutch fans, one is on my car. I always debate on getting an electric fan.
Why does you engine sit low?
You may try Vert. mounts which are a little taller.

 

[2+2GT]

Why does you engine sit low?
You may try Vert. mounts which are a little taller.

A common misconception. Click here:

Mustang Motor Mount Recognition

 

[boatillo]

A 17" clutch fan would fit it perfectly, if the engine sat a little higher - no way am I replacing the motor mounts at this point, and my air cleaner probably would not clear the hood if I did. As it is, a 17" fan barely scrapes the bottom of the shround (tested with everything mounted), a 16.5" fan should give ample clearance after any motor shake.

Would I really unbalance the fan by grinding length off? Worst job I might end up with is the blades being like milligrams off.

Whats with those fans that have 5 or 7 blades that are not evenly spaced? Wouldn't they be an odd balance on your water pump?

 

[boatillo]

Alright I found a 15" clutch fan, which is tiny, but will fit no problem. Is there even a point to using a shroud if the fan blade tips will be like 2" away from shroud's wall though?

1) 5-blade 18.5" fan with clutch and no shroud (been there for years, no boiling over, but I haven't really driven it in hot weather for a long distance)

2) 6-blade 15" fan with clutch and shroud

3) 6-blade 16" flex fan and shroud, no clutch

4) 6-blade 18" fan with clutch and no shroud (better than the 5-blade?)

5) 6-blade fan handcut to 16.5" with clutch and shroud

 

[2+2GT]

A 17" clutch fan would fit it perfectly, if the engine sat a little higher - no way am I replacing the motor mounts at this point, and my air cleaner probably would not clear the hood if I did. As it is, a 17" fan barely scrapes the bottom of the shround (tested with everything mounted), a 16.5" fan should give ample clearance after any motor shake.

Would I really unbalance the fan by grinding length off? Worst job I might end up with is the blades being like milligrams off.

Whats with those fans that have 5 or 7 blades that are not evenly spaced? Wouldn't they be an odd balance on your water pump?

The engine is probably low due to sagging motor mounts. They do that with age. Finding correct 67 replacement mounts is a pain, only GN has mounts the correct fit, and they aren't the cheap ones. The 67 Ford AC fans were 17.5", IIRC.

Balancing a fan is difficult, but not impossible. Get it wrong, though, and it'll kill your water pump quickly.

The 5 and 7 blade fans were very carefully spaced to even the weight. The varied gaps were intended to avoid harmonics.

 

[boatillo]

Every dang thing on these cars is a chore, I swear! Buy the most innocuous part (say my new vent window handles) and it never fits without modification!

I'm going to do a 17" clutch fan and just cut the bottom off this shroud. 3/4 of a shroud is better than no shroud, and the fan runs nearly to the bottom of the radiator anyway.

 

[2+2GT]

I'm going to do a 17" clutch fan and just cut the bottom off this shroud. 3/4 of a shroud is better than no shroud, and the fan runs nearly to the bottom of the radiator anyway.

Don't. It'll kill the structural integrity of the shroud. Move it lower. Many times I have redrilled the mounting holes lower, even ground a bit of plastic to get closer to the lower hose fitting and tank. Anyway, 3/4 of a shroud leaves a gap that just kills it's effectiveness.

 

[boatillo]

Alright, I guess I've made a decision on this then. Went back out an looked at how much lower I could mount the shroud on the radiator - not much. I could gain maybe 1/8" if I cut a lot of the bottom off and then I would have to pack foam around the rest of the edges because it wouldn't sit very level on the rad.

Not worth it, I am going to mount it as it is supposed to go, and switch over to a 16" flex fan and 1" spacer. I will gain 0.5" clearance on the bottom of the shroud, which is quite enough as the fan on there now only clears the tranny lines by that much. The motor mounts are rock solid.

Thanks for the help, I will be creating new posts on power steering and disc brakes in the future!

 

[2+2GT]

I gotta wonder why your engine sits so low.

 

[NY-67stang]

I had a shroud that rubbed too. I had to squeeze the sides inward a bit and that pushed bottom & top out just enough to let everything clear.
The same thing happened with my buddies aftermmarket shroud. He was ready to take it off before I showed up. Mind you it was not enough to deform the shroud, just enough toget everything to clear.

 

[boatillo]

Uggh, I am back to debating what to do.

1) 6-blade 15" clutch fan, shorter Hayden 2765 thermal clutch (to place fan 50/50 in shroud).

2) 6-blade 16" nylon fan, 1" spacer, no clutch.

I read the nylon fans move a ton of air, super light, and 16" would give me 0.5" clearance at bottom, 1.5" left & right, 2" top. Considered better than the steel flex fan?

However, I still like the idea of a clutch, but I am worried a 15" fan is too small. It would give 1" clearance at bottom, 2" left & right, 2.5" top. Top to bottom it covers the rad pretty well (16" rad height, 15" fan's tips are roughly parallel to bottom fins), but rad is 20" wide and shroud has a 19" opening.

I just want to make sure I am pulling enough air to never overheat. A Hayden standard thermal clutch runs the fan from 20-30% of shaft speed when "off" to 60-70% when on. Is a smaller fan that spins slower going to be up to the job? Should I ignore the benefits of a fan clutch?

 

[horseballz]

Is it possible that instead of the engine sitting low, the radiator is sitting high or possibly the wrong radiator for the car?
Just Asking,
Gene

 

[2+2GT]

Is it possible that instead of the engine sitting low, the radiator is sitting high or possibly the wrong radiator for the car?
Just Asking,
Gene

Anything is possible. I have seen some pretty crappy replacement radiators.

And I hate flex fans, no matter what they are made from. They are mindless, and loud, pumping tons of air whether the engine needs it or not. On the highway, a clutch fan shuts down, drifting at low speed, releasing hp and mileage from the engine. This is true at all speeds in cool weather.

There are also other hazards. I once sold a 70 hood to a guy with a BOSS 302. Zipping up the road one day, heard a loud THWACK, and one of his flex fan blades had come off the fan and went halfway through the hood. Not saying it's common, but…

 

[boatillo]

Is it possible that instead of the engine sitting low, the radiator is sitting high or possibly the wrong radiator for the car?
Just Asking,
Gene

Quite possible, as far as I know this radiator is not manufactured any longer; bought from cj pony parts 6-7 years ago. 20" 4-core brass, the pre-drilled mounting holes do not line up with the radiator apron but it is mounted nearly as low as it can go, almost touching car's frame. As with many of our Mustangs mine is quite custom, I don't even remember what year the 351W was manufactured or where my engine builder found mounts that would work, but it all works.

Guess I will order the Hayden clutch and 15" fan, why no one makes a 16" clutch fan is beyond me.

 

[2+2GT]

Guess I will order the Hayden clutch and 15" fan, why no one makes a 16" clutch fan is beyond me.

Doesn't match any original size I know of- no one would need it. Something is screwy if your engine is that far from the center of the shroud.

 

[Pony66]

A common misconception. Click here:

Mustang Motor Mount Recognition

Thank you for that link. I read the last part about the convertible mounts. It states "One common misconception is that convertibles had the engine mounted at a different height than coupes. This is a result of force-fitting the incorrect mounts. The convertible mounts were intended to provide the same installed height. The early/late 66 mounts should also result in the same installed height. "

I thought that the mounts are taller so that the engine sits in the proper location. Everything I have learned was by screwing up the first time.
I just remember ordering special mounts for my vert. It still confuses me.

 

[2+2GT]

Thank you for that link. I read the last part about the convertible mounts. It states "One common misconception is that convertibles had the engine mounted at a different height than coupes. This is a result of force-fitting the incorrect mounts. The convertible mounts were intended to provide the same installed height. The early/late 66 mounts should also result in the same installed height. "

I thought that the mounts are taller so that the engine sits in the proper location. Everything I have learned was by screwing up the first time.
I just remember ordering special mounts for my vert. It still confuses me.

The 67 all had the same frame brackets and rubber insulators. (even the 390 used the same frame brackets). Ford found they had a vibration problem in convertibles. To reduce tooling cost, they simply set the frame brackets at a different angle for the convertible, by moving one bolt hole. This changed the angle of the rubber pad, eliminating the vibration. The rubber and the lower steel part of the insulator were unchanged, but the changed angle required a completely different upper piece. Now everybody's happy, and you simply buy what you need.

Then time passed. Ford dropped the mounts. No worries, Anchor and everybody else still offered the 2257 (ht) and 2286 (cv) mounts. Then Anchor noticed how slow the 2286 sold, and how much it looked like the 2257, and dropped it, telling everyone to substitute the 2257. Of course, it takes a big prybar to do this, and even if you succeed, the engine sits wrong.

Anchor is about the largest maker, so everybody else dropped the 2286, too.

I see the 2286 still offered, on eBay, etc. They are lying. It's a 2257 in the box. I know. I ordered them all.

I once talked to the actual guy at Anchor who decides such things about re-releasing the 2286. He laughed. Said unless I wanted 10,000 of them, no dice.

 

[Max Power]

The 351 engine in my 69 also sits chronically low. The radiator, which is the second 24" one I have had, basically sits on the frame. I have had to cut out the bottom of the last two shrouds I have had. I have a 16.5" flex fan, and it comes within a whisker of actually hitting the tranny cooler lines. I have no idea why.

To the OP, if you are worried about overheating, why not just run a 24" radiator?