Petcock thread size

[Knebel]

Are all Petcocks (drain tap) on a 68 plymouth 1/4 inch or what thread do they have? I am trying to figure out how I can install a coolant sensor, I cant get the plugs out of my manifold.... and need the one spot i have for the sensor already in there. So i thought, just remove the petcock and put a sensor in instead.

 

[Big_John]

Should be 1/4 NPT.

 

[commando1]

A coolant sensor at the bottom of a radiator will give you an abnormally low reading. Not a good place for one.

 

[70bigblockdodge]

Coolant sensor is usually 1/8 NPT

 

[commando1]

Coolant sensor is usually 1/8 NPT

 

[Big_John]

But let's go back to getting the plugs out.

What have you tried? I know that a little heat with a torch goes a long way if there is pipe dope on the threads.

 

[Knebel]

Well, im under a carport in an apartment, that severely limits me. The one I got out before, to install my sensor, i had to drill out. No heat, no soaking worked....

So far i have just soaked it in pb blaster for 3 weeks, put the allen wrench in, used a pipe to have more leverage and the thing does not move one bit. Stopped because i didnt want to break the manifold.

Oh and the lowest i can adjust my thermostat is 150.

 

[commando1]

Is this a SB or a BB?

 

[jct]

have you tried hammering on top of the wrench while trying to get the plug out?

 

[Knebel]

Yes, tried hammering too. Its hard to get to. It is a sb with an edelbrock performer 318/360 intake.

 

[commando1]

Yes, tried hammering too. Its hard to get to. It is a sb with an edelbrock performer 318/360 intake.

And which one is breaking your ballz?

What do you currently have in #1, #2, and #3.
Trying to get a PICTURE of what's going on.

 

[Knebel]

I have a sensor for my electric fan thermostat in 2, water temp std sensor in 1. The rest are plugged with allen wrench pipeplugs. If i rip on it like a berserker, id either break the manifold, bend the allen wrench or round out the plug... but it wont move. The one i got out last year, i tried dry ice, heat, soaking it in all kinds of stuff, nothing.

 

[commando1]

 

[65sporty]

I use a Allen socket with a ratchet, did you drain down the coolant? I will hit the top of the plug with a hammer, use heat, and remove

 

[commando1]

Can try welding a bolt to it.

 

[livininharrow]

you are not trying hard enough. a pipe thread fitting will always come out as it is a tapered thread. you should not have to worry about breaking the manifold. more leverage my friend . also heat as mentioned followed with cold water immediately will tend to break the seal in the threads.

 

[celticwarlock]

This thread is a bit old, but might I suggest an Allen ratchet attachment on an impact gun? I have had a lot of success with that combination. Combined with heating/cooling and even without it, it should prove most effective.