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| 12G938 a different casting of 12G940 ? https://www.ausmini.com/forums/viewtopic.php?f=2&t=61589 |
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| Author: | 74snail [ Sun Mar 07, 2010 10:08 pm ] |
| Post subject: | 12G938 a different casting of 12G940 ? |
12G938 head - is it a different casting of the 12G940 head ? Was just reading about it but not much information that is easy to find, according to some people it had a thicker deck and extra metal around the ports but still 9 head studs Any more information ? . |
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| Author: | 74snail [ Sun Mar 07, 2010 10:21 pm ] |
| Post subject: | |
Actually I should use the search more often  
http://www.ausmini.com/forums/viewtopic ... 0d76048963 and it would seem as though I already have one on the Morris Nomad , but I would'nt mind another
So by answering my own question I have to assume that a 1100S / 1300 auto 12G938 head is the one you want if you want to do lots of mods and metal removal . |
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| Author: | drmini in aust [ Mon Mar 08, 2010 7:19 am ] |
| Post subject: | |
12G938 (stamped near thermostat housing) is an 1100S head. 12G1805 (stamped near there too) is a Mk2 Cooper S head. They are BOTH the same early 12G940 casting (look on top, between rocker posts). The main difference is the Cooper S one has 1/16" bigger inlet valves, and a tidy up inside the ports. And 2 more head stud holes drilled. |
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| Author: | 74snail [ Mon Mar 08, 2010 9:31 am ] |
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Cheers , thanks Mr G . |
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| Author: | drmini in aust [ Mon Mar 08, 2010 2:35 pm ] |
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`12G940' must be BMC/BL/Roverspeak for `cylinder head casting'. 
Just about every 1275 head they've cast since 1969 (apart from the 12G1316 smog one) has 12G940 on it somewhere. |
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| Author: | Drexxle [ Mon Mar 08, 2010 4:16 pm ] |
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my question is: isnt the 12g940 a big block head, and doesnt this need the block pocketed to make it not smash valves, so how is the 12g938 the same if its for a small block. |
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| Author: | EST-071 [ Mon Mar 08, 2010 4:27 pm ] |
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Drexxle wrote: my question is: isnt the 12g940 a big block head, and doesnt this need the block pocketed to make it not smash valves, so how is the 12g938 the same if its for a small block.
A Morris 1100S is in fact a 1275 motor. Cheers Pete |
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| Author: | GT mowog [ Mon Mar 08, 2010 5:04 pm ] |
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Drexxle wrote: my question is: isnt the 12g940 a big block head, and doesnt this need the block pocketed to make it not smash valves, so how is the 12g938 the same if its for a small block.
Just to help (hopefully) clear a point or 2 up here. When the heads are cast, they have cast in to them a number which is from the moulding pattern, in this cast that is 12G940, some refer to this as it's casting number, HOWEVER this is not it's part number. It's part number could be one of several, two of which the Doc has put up ie 12G238 (which is the 'stocker' type) and the 12G1805 (MKII Cooper S / Clubman GT), which both use the same casting but are machined and fitted with different accessories. These heads are loosely referred to as '12G940' heads because that is usually the easiest number to read, however it is incorrect to do so. With the BMC / Leyland stuff, some of it does use the casting number also as a part number, but much of it does not. |
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