Anybody have any good ideas on how to use a cooling fan switch on an LS1? Doing a carb conversion with an electric fan and need to locate a fan switch somewhere in the cooling system.All of the switches I have found are large pipe thread and all the LS motors have is the two small metric threaded holes in the cylinder heads.

 

If you live in a hotter climate like we do here in Houston I would run the fan relay off the ignition switch. Most of those temperature switches don't work well without a computer telling the fans when to come on.

I built a nova with a 750 hp 421ci small block with dual fans and they run all the time even in 50 degree weather and the car runs fine. If you put it on a manual switch you will eventually forget to turn it on and like I said those temp. switches are not reliable.

 

i've got this one. It's adjustabe and goes in the radiator drain.
http://haywireinc.com/catalog/produc...2qvf5ri8dpihs0

 

How does this one go into the radaitor drain??From the pictures it looks like it has a tube that goes under a radaitor hose.

 

It goes in the drain, comes with an npt to compression fitting. The compression fitting tightens around the probe.
You can also thread, 1/8" npt, the end of a standard set switch.

 

Get a spal controller it will use the stock sensor. I just installed one and it works great

Tim

 

+1 on the SPAL Controller. Been using it on my swap for 6 years now.. and never over heated. Can change the settings on the fly...!

If your using a large Sender, you can try using the water pump, the flat area about the outlet. Just drill and tap it

 

Found this last night,Painless Genn III fan switch in kit form or just the switch on @ 205 and off @ 190. It will screw into the cylinder head in the stock location with no adapters.I think it would work OK,we are using an Afco dual pass crossflow radiator in a 62 Nova wagon with a stock LS1.




This Fan-Thom II kit comes with a threaded thermostatic switch that screws into the extra coolant temperature sensor port of the passenger engine head on Generation III and up GM engines for a professional looking installation. This is inexpensive protection for an electric fan and a vehicle's wire harness. Provides constant voltage, protects from voltage and amperage spikes and prevents the fan from back feeding voltage through the vehicle's wire harness.

This kit includes:

SPST 40 Amp relay
30 Amp circuit breaker
12x1.5M Thread Thermostatic switch 205°F On/190°F Off
Relay base with harness
Crimp-on terminals
Mounting hardware

 

I'll be using the PCM to control my fans. It's just one less thing to worry about.

 

The spal is 1/2 the price of the painless and my experience with painless stuff the spal is better overall quality.

I have used spal for years and never had to worry about quality or reliability.

Tim

 

The painless I am talking about is the f5 controler.

Spal also has a $35 relay stat kit.

Tim

 

Use a radiator probe or take some 1.75" tubing and weld a bung. Drill/tap to 3/8NPT and install common switch in a radiator hose

DO NOT INSTALL THE RELAYS TO ENGAGE WITH THE IGN SWITCH YOU WILL BURN OUT THE FAN MOTORS QUICKLY WITH CONTINUOUS USE

 

Spal fans can be run all the time. They specify what version can be.

Cheap fans will have issues.

I ran my spal dual set up for 8 hours non stop on drag week. .

Tim

 

I have a $34 derale controller that uses a probe in the radiator fins. it is adjustable and works fine. Normally I don't like the fin type, prefer something in the head, but like you are finding there isn't much made directly for the LS sensor threads. I put a little plumbers dope on the probe in the radiator to block the breeze and have been running it now for 3 years with no issues. I wired it to the stock relays I got with the Taurus fan. Did the whole cooling system for around $50.

That painless temp switch looks to be the ticket to me. At one point they sold just the switch for $35. Now they only offer it with the relay and wiring kit. Overpriced.

You actually have several other options.

The previous posts list several other places you can fit a larger sensor into a radiator hose or even the top of the water pump housing.

There is a member on here who takes 3/8 or 1/2 in temp sensors and turns them down in his lathe to fit the metric head. He can easily do that with a temp switch too.

You can also drill and tap the head to be 3/8 NPT. A very common mod on here. Both heads have fittings, so you can put it on either side of the motor.

Another option is to drill and tap the brass block heater plug in the side of the block. That is what I did to fit a Datsun sensor. Here is a picture of how to do it.

https://ls1tech.com/forums/album.php...ictureid=55426

 

Scram Speed now makes a thermal switch that screws right into the LS head. 180, 190, 200 degree . Works mint!

https://www.scramspeed.com/products/...witch-180.html

 

Running this on my twin fans….working great so far.