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Fan Control #383334 Tue Mar 04 2008 03:18 PM
Joined: Mar 2003
Posts: 1,354
Weeds Offline OP
Shop Shark
I am nearing the end of the wiring project on my 49 sub. I need to wire the electric fan for the radiator. I don't want to use a toggle switch but would rather use something automatic that turns the fan on and off as needed. My NAPA guys tell me that I need a sensor to tell the relay when to turn the fan on or off. Problem is their sensor is for a system that uses a computer. I notice Summit sells a kit that looks like what I want. 185 on, 175 off. The sensor/switch screws into the block or intake manifold. No mention of thread size or whether its pipe threads, metric or what. I am running a stock 283 and I don't see anyplace to screw this sensor/switch into the block or manifold. Also how do I match up a thermostat with a system like this? Maybe I am not looking in the right place. Have any of you faced this problem and what did you do to solve it? Many thanks in advance. Weeds

Re: Fan Control [Re: Weeds] #383336 Tue Mar 04 2008 03:40 PM
Weeds the sensors I have seen for a SBC & others are all the same thread & screw into the side of the head where your stock temp unit goes. As for the thremostat just run the stock one but drill two 1/8" holes in it so you won't get an air lock & it'll work fine w/your fan & sensor. The sensor will kick on the fan at a certain temp regardless of what thremostat you are running.

Re: Fan Control [Re: Weeds] #383338 Tue Mar 04 2008 03:43 PM
Joined: Mar 2006
Posts: 1,706
SW_Radial Offline
Shop Shark
The sensor from Summitt will screw into a few places do want to keep your temp gauge that screws into the block so that one is used , there should be a plug on your intake somewhere that you can use for the on/off sending unit ..
Yes it will be pipe thread.
worse case you can get a hold of a small block thermosat housing with a pipe plug in it you could use to attach your sending unit.
hope this helps

1952 Chevy Shortbed

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If It Aint Broke Fix It Till It Is!
Re: Fan Control [Re: Weeds] #383339 Tue Mar 04 2008 03:44 PM
Joined: Sep 2003
Posts: 151
Bluepen Offline
Wrench Fetcher
Hey Weed's I've got a double relay set up on my '46.I got the diagram from Mad Elecric and the relays and sensors from Jegs and Painless. I have not had any problems with it so far. As for the thermostat I went with a 180 and thats on a 350 SBC with an aluminum radiator. I hope that helps you out.

Just a firefighter,
Cleverly disguised as a responsible adult
'46 1/2 T Panel
Re: Fan Control [Re: Bluepen] #383348 Tue Mar 04 2008 04:04 PM
Joined: Aug 2004
Posts: 1,068
Hot Rod Dad Offline
Shop Shark
I strongly advise you still have what I like to call a panic switch, wired in parallel with your sensor, so that either one will turn on the fan. The reason for this is that I've had sensors fail before and the engine quickly overheats at the most inopportune time, such as in rush hour traffic on a hot day. Having a panic switch allows you to manually control the fan until you can get home and troubleshoot the problem.

This is why I have always preferred the old-fashioned fixed bladed mechanical fan that uses a thermostatic fan clutch. They don't typically fail, and unless you sit in traffic a lot, they work great. If you do sit in traffic a lot, then you can always have an electric "helper" fan that is manually controlled.

52 GMC 3/4 ton pickup
68 Big Block Vette
68 455 Firebird
Re: Fan Control [Re: Hot Rod Dad] #383603 Wed Mar 05 2008 03:07 AM
Joined: May 2001
Posts: 8,386
Cletis Offline
Extreme Gabster
I used the Centec electronic control on my '56. Summit part #910-64023. It has a pot to adjust when the fan turns on. It also has a built-in relay, but I used it to turn on a separate heavy duty relay. I'm very happy with it.

"It's just a phase. He'll grow out of it." Mama, 1964

1956 Chevy 1/2-ton 3100
1953 Chevy 6100 "The Yard dog"
1954 GMC Suburban Now with a new proud owner.
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Re: Fan Control [Re: Cletis] #383737 Wed Mar 05 2008 06:14 AM
Joined: May 2005
Posts: 9,115
Grigg Offline
Spal makes a nice fan controller, although I have not bought one yet it is on my shopping list.
click "fans" then "accessories" then third from the bottom, Part Number: FAN-PWM

Here is what they say about it:

This water resistant controller is programmable, and will read almost all OEM and Aftermarket sensors on the market.
-Programmable to activate at any temperature
-Factory programmed to 160 Low, 200 High
-Variable speed for reduced fan noise
-Uses OEM or optional SPAL Temp Sensor
-Waterproof extruded aluminum construction
-LED indicators for High, Low, and A/C

This is the instruction manual, tells a lot about how it works,


1951 GMC 250 in the Project Journals
1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
1952 Chevrolet 3800 pickup
---All pictures---
"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-
Re: Fan Control [Re: Grigg] #383899 Wed Mar 05 2008 07:18 PM
Joined: Mar 2003
Posts: 1,354
Weeds Offline OP
Shop Shark
Cletis, went to Summit's website. They do not show a part 910-64023 or a brand "Centec". Also can't find it in their catalog. Where did you run across it? Weeds

Re: Fan Control [Re: Weeds] #383935 Wed Mar 05 2008 09:08 PM
Joined: Feb 2004
Posts: 19,003
Hotrod Lincoln Offline
Find a thermostat housing for a late-model 305 or 350 with a 1/2" pipe plug thread in it. Install your sensor there, and keep the stock temp gauge fitting where it was originally, in the intake manifold.

Use the housing-mounted sensor to trigger a relay, the heavier the better, and include a bypass toggle switch to use in case the sensor/relay system fails for some reason. Those temp ranges sound about right for an engine with a 180 degree stat, which would be original equipment for your 283.

The murder victim was drowned in a bathtub full of Rice Krispies and milk.
The coroner blamed the crime on a cereal killer!

Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
Re: Fan Control [Re: Hotrod Lincoln] #383953 Wed Mar 05 2008 10:16 PM
Joined: Jun 2005
Posts: 1,925
gazim Offline
Shop Shark
Mine was made by - I believe I bought it from Jegs. Has a adjustable reostat and the temp pickup is a thin tube you insert thru the fins on your radiator

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