Merry Christmas all,
I have a fixed drive radiator fan on my 56 Merc and it sounds like an airplane going down the road. I figure that if I put a clutch on the fan it could slip at higher speeds and perhaps quiet down a little. The problem is that there is a little less than 2.5" of clearance between the face of the water pump and the face of the radiator.
Anyone know of a fan clutch that might work in my application?

Pete

Pete:

You might try one of those fiberglass flex fans. The don't take up much room, and the blades "feather" at higher rpm for less drag and noise.

John - "The Hoosier Hurricane"

Thanks John but I hate the look of flex fans. After a little more research I think the best thing to do is to find a stock 5 blade fan like the one on my 57 Ford. the blades are grouped as 3 and 2 with spaces between those blade groupings .
That fan is quiet and I'll bet that the arrangement of the blades is the reason. The current fan on my Merc is a 6 blade unit with evenly spaced blades.
Anyone got a stock 5 blade that they want to sell ?

Lemme guess, an electric is not an option?

My car has a large pitch uneven spaced 5 blade fan that has stainless flexible trailing edge that works very well. I'm not sure what car it is off, except that it is a Ford part and it looks like it belongs, (not like an aftermarket add on). I think a lot of cars in the 70's started getting the flex fans to reduce drag and HP loss at higher revs. It might be worth looking for one, it looks like it would pull more air than the one in the photo and it has the added advantage of the flex blades.

Your wright about the uneven spacing to reduce noise, you will also see that on alternators for the same reason.

I put a clutch type fan, viscous is what I think they are called, on my 57 312". The fan I used I bought from Ford parts in 1963 to put on my 62 406. I kept it when I sold the car and have been dragging it around ever since. I used the shortest fan spacer I had, but the bolts I had were a little long and I wanted it forward a little more. I had a spare spacer I had milled down so it was just a flange with the hole spacing I needed. That was enough for the bolts not to bottom out. I am attaching a picture that may not show enough detail, but you can see it in there. I have close up pictures, but don't have them in my computer. The 5 blade fan may be all you need.

Paul J. - '57 E Code

Well I found the 5 blade fan I wanted on ebay and bought it. Then I took the 5 blade fan off of the 312 I have on the engine stand and installed it on my Merc.

No more airplane, that 5 blade with the gaps brought the fan noise down to about nothing.

The new on will go on the 312 for my 57 Ford .