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Valve sizes

Posted: Thu May 11, 2023 7:54 pm
by les
I have a 12G940 cyl head, as near as I can measure with little measuring equipment, or reference books where I am at the moment, the valve sizes are — Inlet 32mm exhaust 27mm, maybe a fraction larger, sorry for the approximation. The head has a blanking plug fitted instead of a bypass tube. What head is this from ??? Please of course !

Re: Valve sizes

Posted: Thu May 11, 2023 8:21 pm
by svenedin

Re: Valve sizes

Posted: Thu May 11, 2023 8:28 pm
by philthehill
The 940 head was fitted to several variants of the 1275cc 'A' Series engine.
It does not follow that the head was originally fitted to a 1275cc Cooper 'S'.
See chart below for details and valve sizes.
cyl head details (1).jpg
cyl head details (1).jpg (762.93 KiB) Viewed 952 times

Re: Valve sizes

Posted: Thu May 11, 2023 9:40 pm
by les
Thanks Stephen, thanks Phil. I’d say, from that info it’s from Austin/Morris 1300. I was able to eliminate the ‘S’ application as it’s only a 9 stud head. I was a bit mystified by the bypass plug but recall some dispensing with the hose.

Re: Valve sizes

Posted: Thu May 11, 2023 10:18 pm
by paul 300358
The blanking plugs are quite difficult to remove, I found that the best way is to weld a wheel nut to it and then use a long breaker bar.

Re: Valve sizes

Posted: Thu May 11, 2023 10:38 pm
by les
Thanks Paul but I’ll be selling the head, once I find a fair and reasonable price to offer it for.