There are 2 freeze plugs on the INLET SIDE of the 3.8 E Type cylinder head - part no C11530
Anyone know the thread size - 1.1/8 BSP has been mentioned - is this correct and where do I source 2 in no male plugs if this is the correct size.
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Hi , I don’t think they are freeze plugs , as freeze plugs (core plugs in uk) are not threaded , they are designed to pop out if the water freezes . think they must be to blank off the water ways to the e-type inlet manifold , as most heads the water ways are open , see pic , if I come across a supplier I will let you know .
Not much help sorry , but don’t like seeing a question with no reply’s 
The 3.8 Mark X has the same two core plugs and a C.11531 copper washer is used with them, so it must be threaded, not a simple disc.
The first vendor I would try is XKs Unlimited. www.xks.com
They are familiar with all the XK heads.
They are called core plugs because they plug the hole left in the casting from the sand core that formed the internal passages.
The simple disc type plugs are also called Welch plugs after the guys that invented them and marketed them beginning about 1905, and Hubbard plugs after the company that descended from the Welch brothers and still markets them. The story on the Hubbard website is that in 1905 the Welch brothers were out road testing a car they had built and a pipe plug fell out, so they hammered in a coin and it got them home.
This type are sometimes called freeze plugs because, if you leave plain water in the block over the winter and it freezes, sometimes if you are lucky, they will pop out from the ice expansion rather than the ice cracking the block. Sometimes, no guarantee.
Thanks I really appreciate ALL replies.
Finally found some so the work on the cylinder head can be completed.
Because I only have about three threads to read it is hard to tell if they are 11 or 12 pitch without an optical comparator. The UNF would be 1 1/2 X 12 and the BSP would be 1 1/8 X 11 BSP. The BSP is a nominal size measuring 1.492 so very close to the 1.500 of the UNF.
The UK was getting away from Whitworth and going to American threads at that time. At Jaguar, the Mark V chassis and the XK engine were the first major changeovers to the ANF thread system.
The XK engine has no BSPP or BSF threads anywhere that I know of.
Only BSPP that I find are on the carbs and fuel pump which were made by SU.
Rob,
The adapter for the temperature bulb and the heater takeoff are 3/8 BSP,
and the top cover bolts on a Moss box are BSF.
Peter B.
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