sbc...350,180 deg thermostat...16" pusher fan...I'm trying to pick which thermostat wiring kit for the fan... theres so frickin many my heads swelled...i'm lookin at a derale 16738 which is a probe type that goes in the radiator fins..on at 180 deg off at 170....should i go higher ? lower ? i want to get the right one.thanks..........whid
I am using a SPAL I like the idea of using the stock sending unit. It's more accurate than a bulb type outside the radiator. And you can program your own temps. It also ramps the fan up without running it wide open all the time. Not selling the brand or unit just my experiance.
Spend a few extra bucks and get an adjustable controller. I have the derale 16759 in my 37 buick (adjustable with radiator probe) and it works great. Fixed temp ones I have used never worked at their rated temps close enought for me. Derale 16749 uses the screw in sender with the same adjustable controller. Both are under $50 at summit racing.
I personally don't like the radiator push through the fins ones, I like the ones in the coolant. I have one of these on my flathead (msd dist won't clear the stock fan): Sending unit this is the kit sensor AND relay "The Satin are priced @ $56.00 ea. (sensor only)" Also one of these: Relay
For $30 get the one that goes into the bottom of the radiator replacing the petcock and has an adjustable control. Works great.
I don't like the ones that go on the radiator either. I had great luck with this in an OT car ('86 Regal 455 Buick) http://www.painlessperformance.com/webcatalog/largeview.php?SearchField=30103 You can also get the switch only (30111) if you don't need the relay and wiring.
I welded a 1/2 NPT bung near the radiator inlet (upper hose) for the thermal fan switch. The fan relay is hidden beneath the filler panel on the front side of the core support.
No one has mentioned it yet, but make sure that your fan on temp is HIGHER than your thermostat temp. It does absolutely no good to have the fan on and the thermostat closed. With a 180 (F) thermostat, I would look at a fan controller that turns on at 195 (F) and off at 190 (F). Good Luck.
Can you give a bit more info on this? A part number etc, I have searched around for options and don't remember ever seeing a setup like this. Thanks RustyNCA
Try and find a temp sender unit (goes in engine and senses coolant temp) that closes the switch inside at 195-200 degrees. Just wire up a relay to the sender and power and connect fan supply to other terminal on relay. Anybody putting a sender unit at the bottom radiator hose or tank is going to get a very different reading than the engine itself.
Why would you want a fan controller at the bottom of the radiator where it is reading already cooled coolent.
I pretty much feel the same, a temp switch (sender) in the engine that switches on a "temp A" and off at "temp B", and a relay makes for a dependable clean professional installation. I hate those radiator probes, even if they work ok they just look like cheese to me..... My ultimate answer is in my sig right now though.... http://www.wellsve.com/custom_searches/ds_fans.php?switch=sw555&submit=Submit
I don't know, I've got a switch in the bottom of my Griffen alum. radiator that's on at 200 degrees and off at 190, I use a 195 degree thermostat and when my SW temp gauge hits just under 200 the fan comes on, shuts off around 192-193. I'm guessing that's becaues the fan cools the water in the radiator not the engine. I've been happy with mine, so far. I think you are right in saying the reading will be different if the switch was in the engine but it's not much different, at least not on mine.
My cooling combo: 1956 F100 Stock SBC, no mechanical fan 3-Row Copper Radiator 16" Electric Puller Fan Only 205*/195* Coolant Temp Sensor in cylinder head Manual Switch on Dash 195* Thermostat 20 oz. Stainless Overflow Tank Maintains 195* around town/highway. Even at 105* outside, sitting in traffic for an hour, it won't go over 210*. Fan comes on at 205* and runs til temp drops to 195. I don't even have a fan shroud...I imagine it would run a little cooler with one, but it does well in the Texas heat, so I'm happy with it.
I use an electro-mechanical switch with a bio-mechanical controller that visually senses the temperature gauge.... a switch on the dash controlled by my finger.....
Altho my fan is controlled by a thermal fan switch I also have a manual switch on the dash "just in case". I also have a small LED on the dash to let me know if the fan is on or not... overkill, maybe.
If the radiator is cooling the coolant sufficiently without a fan, there is no need to turn on the fan. You don't need to know how hot the coolant going into the radiator is, you need to know how hot it is when it leaves the radiator. If you use a 180 degree thermostat and the coolant entering the engine is still 180 degrees, it can't soak up heat and stay at 180 degrees so the fan needs to run.
I think I would rather control my engine's temperature where it is hottest, before the coolant enters the radiator, not the temperature of the coolant returning to the engine. Believe me, that water entering the engine is not going to stay 180. Too many veriables. Just my 1¢ worth...
If the coolant coming into the radiator is 195 degrees and goes out at 110 without the fan running, why would you turn on the fan? You need to know when the radiator isn't cooling the coolant enough. You can only tell that by checking the output temperature.
Same as Y-Blockhead.... "just incase". I can flip the fan on manually, which I never really do, but it's there if I need to. The switch is a lighted rocker type, so I can tell if the fan is on or not. Also, if the thermal switch activates the fan, I can flip my switch to the on position and if the light is off, the fan is running. This is just peace of mind if the relay craps out, I can still manually turn the fan on and drive on. I do carry a spare relay in the fuse box if that ever does happen. Also, I forgot to mention I run a 7psi cap.
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