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Discussion Starter #1
Where should I install the fan temp sensor? It's a 180* sensor, and the manifold to radiator thermostat is a 190*. If the fan sensor is located in the intake manifold, won't the fan run at all times unless the engine is cold?
Also, where do you plumb the heater to on the manifold/ pump?
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The heater return goes to the pump, the inlet to the front passenger side outlet port on the intake. I would swap out the 180* fan sensor for at least 190*, in can be in the second outlet on the manifold, or you can install a tee and use one outlet for both.
 

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Here are a couple of pictures of my setup. Breeze sells a T for the front passenger side port that allows you to run the heater and a sensor. I found that the fan sensor wouldn’t trigger the fan in this spot unless I had the heater on a little. A bypass heater control valve would have solved that problem but, I ended up installing a thermostat housing like the one pictured and put the fan sensor in that port. Rich is correct, you need at least a 190 degree on switch. I am converting to a Holley Sniper EFI system and it will control the fan so you can have the thermostat housing and switch for the price of shipping if you want.

HTH

Norm
 

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Discussion Starter #4
I've read about some who put it in the drainage petcock bung in the lower PS radiator. Any benefits putting it here vs in the manifold? Any reason why should I get a higher temp fan sensor if the thermostat in the water neck is a 190*? is this to prevent the fan from running continuously? Does the coolant temp vary depending on where in the manifold you place the sensor? I'm guessing that it would. would placing it in the radiator allow you to run a lower temp fan sensor since it's had some time to cool off?
I'm trying to figure out a way to keep the fan from running continuously.

The heater return goes to the pump, the inlet to the front passenger side outlet port on the intake. I would swap out the 180* fan sensor for at least 190*, in can be in the second outlet on the manifold, or you can install a tee and use one outlet for both.
 

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My setup was a 180 thermostat with a fan switch on at 200 and off at 185. The fan would be off while driving at highway speeds and come on in stop and go traffic.
 

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You have (or maybe will have) the same situation as me. I used to use one of those temp sensors that you shove the probe in between the radiator core tubes. Then I re-did the fan control and put a sensor in the fitting driver side front of the intake. I had 2 sensor options 180 and 195. Seemed to me that a 180 would have the fan come on and never go off, so I used the 195. I also have a manual toggle switch. For me the temp sensor is more of a fail safe function for when I forget to flip the switch. I am a bit weird in maybe worrying too much but I don't especially like the temp sensor operation as the engine cycles from 180 to 195 to 180 etc if I let the sensor do all the work. So I flip on the switch whenever it is hot out and then, no matter how hot it gets, the engine is rock solid 180 all the time.
 

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In your picture, the square pipe plug would be the one going to the heater control valve with the return to the water pump as mentioned. The hex fitting can be used for your engine temperature gauge.

I run my fan switch from the lower hose area (inlet side) of the radiator. I soldered a pipe fitting into the tank for the fan switch. This way it reads the true temperature of the coolant/water. You can use your petcock port if you want, just keep in mind you'll be removing (with a mess) the lower radiator hose when draining, or you can put another in-line hose petcock to serve that purpose.

I'm not a fan (no pun) of the "T" stat housing port due to it's inconsistencies with true constant readings.
 

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Discussion Starter #8
You have (or maybe will have) the same situation as me. I used to use one of those temp sensors that you shove the probe in between the radiator core tubes. Then I re-did the fan control and put a sensor in the fitting driver side front of the intake. I had 2 sensor options 180 and 195. Seemed to me that a 180 would have the fan come on and never go off, so I used the 195. I also have a manual toggle switch. For me the temp sensor is more of a fail safe function for when I forget to flip the switch. I am a bit weird in maybe worrying too much but I don't especially like the temp sensor operation as the engine cycles from 180 to 195 to 180 etc if I let the sensor do all the work. So I flip on the switch whenever it is hot out and then, no matter how hot it gets, the engine is rock solid 180 all the time.
I have a 190* thermostat on my intake, so maybe I'll get a 195* fan temp switch that can keep the temp between 190-195.
 

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With a 195 on switch your fan will run all the time as the off temp is either 180 or 175 on the ones I can find.
 

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Discussion Starter #10
ok. large front PS 1/2" NPT plug will be needed for fitech temp sensor. can I plumb the heater to one of the smaller 3/8" NPT bungs?
 

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Discussion Starter #11
ok. just realized that w/ fitech, it has it's own temp sensor. that solves the fan thermo switch issue.
 

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Which other bungs are you referring too? I would not use the two at the back of the manifold. They might cause hot spots in the cylinder heads when the heater is in use. Coolant flow in the engine is primarily front to back through the block and then back to front through the cylinder heads. The hottest coolant is at the front top of the engine and that is where you should have your temperature sensors. Here are a couple of pictures. First is my original setup. The sensor in the T to the heater hose is now going to be the sender for my gauge. I have incorporated a flow through device into the heater hose system to allow a constant flow of coolant past the sender without the heater being on.

I copied your picture and added some things.
The nipple on the water neck goes to the pump as indicated by the black line.

1 is where your Fitech temperature sender should go.

2 is the outlet to your heater

3 is the return line nipple for your heater.

This leaves you with having to find a spot for your gauge sender.

HTH

Norm
 

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Discussion Starter #13
Which other bungs are you referring too? I would not use the two at the back of the manifold. They might cause hot spots in the cylinder heads when the heater is in use. Coolant flow in the engine is primarily front to back through the block and then back to front through the cylinder heads. The hottest coolant is at the front top of the engine and that is where you should have your temperature sensors. Here are a couple of pictures. First is my original setup. The sensor in the T to the heater hose is now going to be the sender for my gauge. I have incorporated a flow through device into the heater hose system to allow a constant flow of coolant past the sender without the heater being on.

I copied your picture and added some things.
The nipple on the water neck goes to the pump as indicated by the black line.

1 is where your Fitech temperature sender should go.

2 is the outlet to your heater

3 is the return line nipple for your heater.

This leaves you with having to find a spot for your gauge sender.

HTH

Norm
Thanks Norm.
The fitech temp sensor is a 1/2"npt fitting, so the only bung this would work with would be at the front PS where you indicate the heater intake goes. Unless I can find a 3/8" npt temp sensor. With your bypass coming off your thermostat housing going back to your pump, do you have an overflow coming off a filler T piece that runs to your overflow tank? Also do you find that your temp sensor going into your T piece on the manifold accurately records the temp? I've seen others report that the temp sensor isn't accurate unless they have the heater on, allowing fluid to run through that area.
 

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Are you sure the Fitech sensor doesn't have an adapter on it to take it out to 1/2 npt? As for the heater lines and coolant flow, I made this gizmo to allow a small amount of coolant to circulate even when the heater is off. Haven't tried it yet so don't know how well it will work. Will compare my gauge readings to the Sniper display when I get it running again.

The overflow/surge tank line comes off the T filler. I have the Breeze "it's not fancy but it works" surge tank. The bypass nipple on your thermostat housing has got to be connected to the water pump. This circulates coolant while the engine is warming up and the thermostat is closed to allow even engine warming. Without this connected you will get extreme hot spots in your cylinder heads, especially around the exhaust ports.

Norm
 

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Discussion Starter #15
Are you sure the Fitech sensor doesn't have an adapter on it to take it out to 1/2 npt? As for the heater lines and coolant flow, I made this gizmo to allow a small amount of coolant to circulate even when the heater is off. Haven't tried it yet so don't know how well it will work. Will compare my gauge readings to the Sniper display when I get it running again.

The overflow/surge tank line comes off the T filler. I have the Breeze "it's not fancy but it works" surge tank. The bypass nipple on your thermostat housing has got to be connected to the water pump. This circulates coolant while the engine is warming up and the thermostat is closed to allow even engine warming. Without this connected you will get extreme hot spots in your cylinder heads, especially around the exhaust ports.

Norm
OK, I checked and you're correct. the Fitech I got was a used unit, and there was an adapter taking the 3/8" NPT up to a 1/2" NPT. i'll likely put the heater on the PS 1/2" bung and pick the DS front 3/8" for the temp sensor for the EFI.
 
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