What thread size is the cooling system's cylinder block drain plug?

I am working on a 1966 block, and I want to replace the plug because it is pretty rounded-off.

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63 Signet / 10 inch front drums / weber 2bbl / HEI / 2.76 rear end

NPT ?

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63 Signet / 10 inch front drums / weber 2bbl / HEI / 2.76 rear end

I have blocks with plugs from 1/4" pipe to 1/2" pipe. You'll just have to get it out and see.

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Official Cookie and Mater Tormentor.

I believe that my '62 is 1/2" NPT. (I can just get my index finger through the hole, and 3/8" is too small.)

Is it possible to get at the block drain plug while its in the can?
Can someone post a pic of where it is? I want to put a temp sensor in there for a thermo fan to replace the stock unit.

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Chris


The Wayfarers

six 'n out

Not a good place for coolant temp sensor - It's about half way through the coolant path and will measure colder. You want it as close to the thermostat as possible to measure the highest temp.

It's about half way between the oil pump and transmission on the side opposite the manifolds. You can reach it easily on US cars. With your steering stuff there, I can't be certain.

^^^ As above, it is a low flow area of the block and the coolant temp there could be well below the rest of the system's temperature.