I have changed basically everything under my hood. I am running a carburated 350 out of a 1981 pickup with an RV cam and a high rise aluminum intake, and a points type ignition. anyways, the computer isn't used for anything; in fact, i removed the ECM and wiring harness completely (except the couple wires going to the tranny and VSS buffer). I have a Modine 4 row radiator in place of the stock one, and i mounted a 15" clutch fan off of an s-10 blazer and custom made a fan shroud. this setup works great except when sitting in traffic, which is why i have an electric fan placed in front of the radiator. currently, i manually turn the fan on, but my goal is to have this fan setup to automatically turn on when my temp hits 175-180 or higher (i am running a 160* thermostat)

I was hoping i could build a circuit that would be connected to the temp guage sending unit on the side of the block. this circuit could trigger a relay when the temp reached a certain point. I could test the resistance of the sending unit at this temp by placing it in a pot on the stove with a thermometer. the only problems is that i have no idea how to design circuits.

thanks in advance

 

Spal makes a electric fan circut that is adjustable and has a sending unit.

Goto www.Spal-usa.com

If you can't find what I am talking about send me a PM and I'll get you the part number. I think that the kit is about $50.00

 

found a bolt in thermostat that turns on at 185 and off at 165, $28.95.

thanks dude

 

i bought a kit from summit that works both of my fans and threads into the manifold, heads or anything else you can find. it also hooks to an acc output so it turns off 30 seconds after the car. its adjustable and turns off 10 degrees below when it turns on.
if you look under heating and cooling, then fan switches thermal, then universal, then go from there. it was 40 bucks and only needs wires hooked up and extended as necessary. havnt finished hooking it up yet but seems like a good idea

 

Once you get the switch, you'll still have to run it through a relay due to the current draw of the fan. If your car originally came with an electric fan, the relay may still be mounted to the driver's side firewall. If not the relay runs around $20 at a parts store (or hit the yards, you'll want the pigtail too). Power wire to and from the relay should be 12 guage, unless the fan you have uses less?

If you don't have the existing relay/pigtail and can get a kit for $40, it's a good deal.

 

the part im talking about from summit has a relay and a fuse. all you need to do it just hook up like 6 or 8 wires and mount it with 2 screws

 

I already have the relay in my car setup with a manual switch, I just want something that will turn it on automatically if the temperature rises; especially if i leave my car idling outside for a few minutes and i walk back to find my temp is up to 220 from 160 in 10 minutes.

 

If your passenger head has the provision, you can go with the factory switch for around $8-10. It will run, or course, at factory temps which may be a little higher than you'd like. The more expensive switch can be used but you'll have to find a place to install it. It may or may not fit in the factory location. Carb'd and TBI f-bodies have fittings in the water neck for the ecm's coolant temp sensor that might work, or you could tap a water passage on your manifold.