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So, while the stang is at the body shop, I've been aquiring some parts for upgrade to the 66 289. A 500cfm Edelbrock carb and an older weiland intake was picked up from the used market.
Anyhow, I went ahead and rebuilt the Eddy. While inspecting the old Weiland intake, I noticed that the temp sensor had been ground down into the aluminum. I didn't ask why, as the guy basically gave it to me.
Anyhow, threw it up on the mill to get it cleared out and was going to weld up the ground down edge.
After getting the old sensor out, I noticed that the threads are significantly deeper than the sensor. It's a 3/8 pipe thread on the sensor, but when i thread it into the sensor hole it seems fairly loose. Mind you there's no teflon on it at the moment.

My question is, is this fairly normal? Or did someone happen to run a 3/8 straight thread tap in this hole possibly? Or is there a much longer sensor that I should be using. When the sensor is threaded at full depth, there isn't much protruding into the flow of water. Also, if I was to use sealant to put this in, doesn't it ground to the motor? It's a one wire hookup, so it makes me think no.

Should I just get rid of it and buy a new intake instead? Am I just asking for trouble here?
 

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Yes, it grounds through the engine. Apply sealant to the threads and screw it in. Set your VOM to ohms and touch one probe to the brass part of the sensor and the other probe to the manifold. If the ohms read a very small number (1 ohm or less) your sensor is making good electrical contact with the manifold.
If the sensor tightens up in the threaded hole as you screw it in it has not been messed with. It doesn't really need to be exposed directly to the flowing water as long as it is near the water. Some people ask about putting a T in the manifold and attaching 2 sensors to the T- 1 for an electric fan temp sender and 1 for the gauge temp sender. This is not recommended as the senders are exposed to "stagnant" water.
 

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The temp sensor on my E-Brock intake needed a brass adapter, maybe yours does too. Like awhtx said, it doesn't have to come in contact with the coolant. It's a closed system so the temp anywhere inside the water jacket will be picked up by the sensor.
 

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Discussion Starter #4
Yes, it grounds through the engine. Apply sealant to the threads and screw it in. Set your VOM to ohms and touch one probe to the brass part of the sensor and the other probe to the manifold. If the ohms read a very small number (1 ohm or less) your sensor is making good electrical contact with the manifold.
If the sensor tightens up in the threaded hole as you screw it in it has not been messed with. It doesn't really need to be exposed directly to the flowing water as long as it is near the water. Some people ask about putting a T in the manifold and attaching 2 sensors to the T- 1 for an electric fan temp sender and 1 for the gauge temp sender. This is not recommended as the senders are exposed to "stagnant" water.
It only tightens up when the hex portion is completely tight to the bottom. It doesn't necessarily tighten up like a pipe thread bottoms out at the narrow portion of the male end.

I can check resisitance as noted though.
 

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Discussion Starter #5
The temp sensor on my E-Brock intake needed a brass adapter, maybe yours does too. Like awhtx said, it doesn't have to come in contact with the coolant. It's a closed system so the temp anywhere inside the water jacket will be picked up by the sensor.
I was curious of this too.
 

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That isn't going to work as a PO has tapped the hole too deep. You mentioned a mill in your opening post so I'd mill it down until the sending unit will tighten up before the hex bottoms out.

Your other option is to drill and tap the manifold for 1/2" NPT. Then get a 1/2" NPT to 3/8" NPT bushing. You can buy one at the hardware store that is nothing but an external 1/2" NPT and an internal 3/8" NPT with no hex at all.
 

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Discussion Starter #11
That isn't going to work as a PO has tapped the hole too deep. You mentioned a mill in your opening post so I'd mill it down until the sending unit will tighten up before the hex bottoms out.

Your other option is to drill and tap the manifold for 1/2" NPT. Then get a 1/2" NPT to 3/8" NPT bushing. You can buy one at the hardware store that is nothing but an external 1/2" NPT and an internal 3/8" NPT with no hex at all.
I thought it was awfully deep. Bummer.
Yes, I could drill/tap for 1/2" NPT and bush it down. Or I guess I could just buy another intake.

I didn't want to get too deep into aftermarket parts that wouldn't swap over if I decide to go 351W . Need to get it on the street first and enjoy the 289 before I make motor decisions.
 

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So, while the stang is at the body shop, I've been aquiring some parts for upgrade to the 66 289. A 500cfm Edelbrock carb and an older weiland intake was picked up from the used market.
Anyhow, I went ahead and rebuilt the Eddy. While inspecting the old Weiland intake, I noticed that the temp sensor had been ground down into the aluminum. I didn't ask why, as the guy basically gave it to me.
Anyhow, threw it up on the mill to get it cleared out and was going to weld up the ground down edge.
After getting the old sensor out, I noticed that the threads are significantly deeper than the sensor. It's a 3/8 pipe thread on the sensor, but when i thread it into the sensor hole it seems fairly loose. Mind you there's no teflon on it at the moment.

My question is, is this fairly normal? Or did someone happen to run a 3/8 straight thread tap in this hole possibly? Or is there a much longer sensor that I should be using. When the sensor is threaded at full depth, there isn't much protruding into the flow of water. Also, if I was to use sealant to put this in, doesn't it ground to the motor? It's a one wire hookup, so it makes me think no.

Should I just get rid of it and buy a new intake instead? Am I just asking for trouble here?
It's (probably) a manufacturing defect....... although it could be that someone tapped it out with a straight tap.
I've seen a few of those manifolds where that particular hole had a hex plug from the factory, but it was in way deeper in the hole than it should have been.
Awhtx's repair advice is the best course if you wish to repair that defect.
 

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Discussion Starter #13
Like i mentioned, it sure feels like it's a straight tapped hole until you get way at the bottom it will taper. What to do, what to do.... For the $180 vs the few hours of drilling/tapping that thing. Might just not be worth it.
 

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I have a mill and a 1/2" NPT tap so it would take me about 30 minutes to do it. That vs a couple of hundred bucks would be a no-brainer decision for me.
 

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That looks like a straight tapped hole to me. By the looks of the milled surface someone tried to make a repair. Find a bolt that size and see how it fits.
 
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