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Discussion Starter · #1 ·
I am looking to replace the piece on the picture with one that has a spot for a sensor. The trouble is I don't know what I am looking for. So what's the name of that shiny piece/neck thingy connecting the radiator to the engine block?
617587
 

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Just so you know, any temperature sensor that you use on the housing won’t give you an accurate temperature reading of the block or heads.
that’s because you’ll be using a source down stream of the thermostat.
better to use a spacer under the housing that has ports to use on it.
like this.



 

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Discussion Starter · #4 ·
Just so you know, any temperature sensor that you use on the housing won’t give you an accurate temperature reading of the block or heads.
that’s because you’ll be using a source down stream of the thermostat.
better to use a spacer under the housing that has ports to use on it.
like this.



Very interesting. But we're talking the difference in distance of about 2 inches, if that. Does it really make that big a difference in temp?
 

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Emphasis on SMALL hole. -1/8" On the side of the cylinder head , between number1&3 cylinders, below the spark plugs , their should be a 1/2" pipe plug , chev used that port for the engine temp . sensor on many vehicles for many years .
 

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Discussion Starter · #10 ·
Emphasis on SMALL hole. -1/8" On the side of the cylinder head , between number1&3 cylinders, below the spark plugs , their should be a 1/2" pipe plug , chev used that port for the engine temp . sensor on many vehicles for many years .
There is a 1/2 hole between cylinders 8 and 6. It's currently used for the temp gauge sensor. The one on the thermostat housing will be used for the fan sensor. That's the plan anyway.
 

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Discussion Starter · #12 ·
What about between 1&3 ?
Actually. Yes. There is a hole there as well. And there appears to be some sort of sensor screwed in there. None of my 3 aftermarket gauges (oil pressure, temp, battery) are connected to it. The wire disappears into the tick wad of wires hidden inside a plastic wire sleeve. My assumption is it is connected to some factory warning light on the dash. What's your opinion?

617618
 

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You can buy a thermostat housing that goes up a little farther before it turns 90 degrees and that should give you access to the threaded port that is next to the housing. I moved my gauge sending unit there because it’s got 1/2” threads, but my new heads only have 3/8” threads for the sending unit.

There may be a slight difference in temp measurement compared to the temp at the head, but I’m using a high flow thermostat with the small bleed hole and the temps seems to read accurately at that manifold fitting.
 

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Discussion Starter · #15 ·
That's probably for the warning light . What does the sensor in your intake control ?
That one turns the fan on. Except that it's currently screwed into the spot where there should be a heater hose. I'm hooking the heater hoses back up so I need to move that sucker. Hence I need a thermostat housing with a plug in it.
 

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Discussion Starter · #16 ·
You can buy a thermostat housing that goes up a little farther before it turns 90 degrees and that should give you access to the threaded port that is next to the housing. I moved my gauge sending unit there because it’s got 1/2” threads, but my new heads only have 3/8” threads for the sending unit.

There may be a slight difference in temp measurement compared to the temp at the head, but I’m using a high flow thermostat with the small bleed hole and the temps seems to read accurately at that manifold fitting.
That's a good point. It's so tightly wedged under that hose though, I wonder how much I would need to extend the neck by. Do you have a suggestion for a spacer or a thermostat housing that gives me the room I need?
 

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Why not then remove the thermostat altogether?
The thermostat continues to work normally at least with a 1/16" hole. The thermostat housing was the only place left for a temp sensor on a 350 in my '32 ford. I brazed the fitting on a Danchuk repro cast iron thermostat housing. Ditto on the comment on not not using chrome pot metal housings.
 

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The coolant return is often called a ‘water neck’ in catalogs. The thermostat brings the engine up to operating temperature sooner than if not present. This controls the operating mechanical clearances which are not the same cold static clearances you measured when putting it together at room temperature. Getting the engine up to temp evens out the cylinder to cylinder power because the front pair run cooler than the middle and certainly the rear cylinders. The bypass is used for several purposes but reducing the chill on the front cylinders is a big part of its function while the thermostat maintains the average coolant temp.

The hottest parts of an SBC is the center adjacent exhaust valve seats. GM normally takes he’d coolant off the drivers side head between cylinders 1 and 3 as this is just a bit off the hottest spot in the engine and the first to see trouble if it’s brewing. This is the hottest spot not only because of the adjacent exhaust seats being near by but also with a clockwise turning coolant pump it’s output slightly favors the passenger side, an out come of the direction of pump rotation. There is an internal bypass on the passenger side used to balance the flow slightly, it was eliminated on the counterclockwise rotation serpentine belt drives starting on the 96 Vortec.

Bogie
 

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Discussion Starter · #20 ·
The coolant return is often called a ‘water neck’ in catalogs. The thermostat brings the engine up to operating temperature sooner than if not present. This controls the operating mechanical clearances which are not the same cold static clearances you measured when putting it together at room temperature. Getting the engine up to temp evens out the cylinder to cylinder power because the front pair run cooler than the middle and certainly the rear cylinders. The bypass is used for several purposes but reducing the chill on the front cylinders is a big part of its function while the thermostat maintains the average coolant temp.

The hottest parts of an SBC is the center adjacent exhaust valve seats. GM normally takes he’d coolant off the drivers side head between cylinders 1 and 3 as this is just a bit off the hottest spot in the engine and the first to see trouble if it’s brewing. This is the hottest spot not only because of the adjacent exhaust seats being near by but also with a clockwise turning coolant pump it’s output slightly favors the passenger side, an out come of the direction of pump rotation. There is an internal bypass on the passenger side used to balance the flow slightly, it was eliminated on the counterclockwise rotation serpentine belt drives starting on the 96 Vortec.

Bogie
This is great insight. Thank you.
 
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