How close or how far should a mechanical fan be from the radiator? I will make a shroud to fit, so it is not part of the equation right now.
I've heard 1-2 inches...but with a shroud, I don't think the measurment makes that much difference... R-
I heard about an inch away from radiator without shroud.If your running a flex fan,allow some area for movement.I have always been told when running a shroud the fan should be half in half out to draw the air flow the best.
I agree, the closer the better without a shroud, down to 3/4 " minimum clearance, with a shroud It's less critical, though I would still consider 1 1/2" as a maximum for good cooling.
I've always shot for 3/4"-1" if not using a shroud. Any more than that and you start recirculating the engine compartment air from the side in stead of pulling air through the radiator core...requiring a shroud to be certain that the air must p*** through the radiator core. JMO
No less than 1" for engine shift in hard braking. 99% of peple say, but mine is closer than that and nothing happened but 1% will tell you it cost them an $800 radiator. With a shroud you can afford to give it more room and would be wise to.
Shoot for about 1/2"-3/4" clearance from fan to radiator. The very important shroud should have 2/3 of the fan inside the shroud and 1/3 of the fan outside the shroud. Preferrably the shroud would have no square corners to trap hot air, although my A coupe 327 W/ a full hood barely gets to 180 degrees W/ the AC on using a home built square cornered aluminum shroud. Remember, what you are trying to achieve is to get fresh air through the radiator and out of the engine compartment.
I have built some very elegant fan shrouds, some of them for folks here on the H.A.M.B., and I can p*** on some useful information concerning radiator to fan spacing. 1. If you don't intend to use a fan shroud, and you can easily install the fan blade without the radiator fins s****ing all the skin off your knuckles, then the fan is probably too far away. I'm being sarcastic, yet I never seem to see one work properly without some sort of human flesh dangling from something razor sharp. 2. I would definitely use a fan shroud. They are easy to make and if made well, they work extremely well. If you live in a warm climate, a fan shroud should be thought of as a necessity. If you are stacking A/C condensers, supercharger inter coolers and so on in front of the radiator, then a fan shroud becomes mandatory. 3. With a properly designed fan shroud (i.e., no significant air leakage, no portion of the radiators core not having air drawn through it, etc..), one can not only hope to retain more fingers, but one can get away with murder, so to speak, with the fan spacing. 4. Based on my experiences, I would keep several things in mind. a). Leave yourself as much room as possible to install everything that needs installing. This sounds like common sense, but everything becomes a battle field the minute all of your nice parts that fit perfectly when you mocked everything up, become painted and pretty. b). Leave enough of a gap between the circular opening of the fan shroud and the fan blade tips to slide your fan belt through. This feature will come in very handy during the initial installation of the fan belt as well as if you ever chuck a fan belt out in BFE. You also need some room between the shroud and the fan blade to compensate for engine movement/shaking, etc., how much compensation you need depends on how your engine is mounted. You don't want the fan blade to hit the shroud, but you want it to fit nice and look concentric. c). If you are building a fan shroud for an early car, say like a 32 Ford for example, that requires the radiator and radiator shell to be able to be nudged around a bit before all of the sheet metal correctly lines up during final ***embly (and we all know how nothing on a car ever fits again once you paint it), you would benefit if the fan shroud had some built in adjustment side to side as well as up and down. You want to be able to get everything right where you want it during the final installation. d). A two piece fan shroud with a top half and a bottom half is a real darn handy thing if you ever have to service anything in the future, say like a water pump, belt, hose, timing chain and so on. Not that any of these things are prone to failure on YOUR car, it just makes your buddies fan shroud look like **** when his parts fail. e). Make your own fan shroud out of steel. You can weld it, add adjustable mounting tabs, bodywork it in fire and brimstone like a blacksmith, roll it, slice it and dice it and do whatever you want to with it to make it your own. Try any of that with one of those plastic aftermarket shrouds and you will quickly dislike plastic. Yes, aluminum is great as well, but I personally can do more interesting things with steel in much less time. 5. Bearing all of the above in mind, and to answer the fan blade spacing question in this current context of using a fan shroud. Center the fan blade in the fan shroud opening. Center it in every conceivable direction. Any air that the fan pulls will come through the radiator, as it has no choice now. Yes, I am aware of all the ifs and buts, air slippage, planetary alignments and so on. The same advice still applies. The fan spacing can be where ever you want it to be or need it to be, within reason, with a cleverly designed fan shroud.
Thanks everyone, I shall go forth tomorrow and make a mount for my 46 Ford. The fan and the radiator what to share the same spot right now.
The Jalopy Journal
