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Post by Deleted on Oct 5, 2009 19:50:43 GMT
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Post by MiniHaven on Oct 5, 2009 20:30:45 GMT
give Johnspeed a call as it looks like one of carls jobs .
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Post by Deleted on Oct 5, 2009 20:43:16 GMT
thank you
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Post by MiniGT5 on Oct 6, 2009 3:45:38 GMT
Looking at it I would say it was a standard A- Series 11 Stud leaded head I can see it has had some work done to it double valve springs etc. 17 is probably the chamber size which will give you a really hi CR. 13 is probably the valve clearance  What sive are the valves, what are the ports and valve guides like N  |
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Post by paul1275s on Oct 6, 2009 15:06:04 GMT
I agree with Neil on the 17 for the combustion chamber volume. Not sure about the .130 though, could be the amount the head has been skimmed by, which also correlates with the smaller than standard chamber volume. (should be 21.6cc on a standard 12G940)
12G940 is the casting number for a 1275 head, no way of telling whether or not it is unleaded (without looking at valve seats), it's age suggests that it would not have hardened valve seats as standard although it may well have been converted. Also the drilling for the 10th and 11th stud/bolt may have been added later.
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Post by Deleted on Oct 6, 2009 20:24:10 GMT
12g 1805 on the thermostat end is cooper "s" 17cc vlm
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Post by Deleted on Oct 7, 2009 14:34:12 GMT
is that good
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Post by paul1275s on Oct 7, 2009 17:48:51 GMT
Well, to translate all the technical talk for you, It is a late sixties to early seventies A series (not A plus) head from a 1275 engine. It has been modified to some degree, we would need to see piccys of the ports and chambers to confirm. It will not have been an unleaded head when new, it may have been converted, again we would need to see pictures or inspect the head to see for certain. It was used on the Mk3 Cooper S and also the MG1300/1300GT cars. It used to be THE head to have, it has nearly the biggest standard valve sizes fitted to an A series (35.2mm inlet, 29.2mm exhaust) and also has the catchet of being a Cooper S head even though it was fitted to other cars. Still fairly sought after, they are getting rare, worth even more if it has been ported or if it has had hardened valve seats fitted to allow use with unleaded fuel. Also if the chambers have been reduced to 17cc from the 21 cc it was originally it will make for quite a high compression engine which may not run that happily on 95 octane unleaded.
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Post by MiniGT5 on Oct 7, 2009 17:54:32 GMT
But you can always used dished pistons or just use an octane booster and all should be OK. I presume this is what came off your 1330 engine did that have dished pistons N |
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Post by Deleted on Oct 7, 2009 18:24:45 GMT
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Post by MiniGT5 on Oct 7, 2009 18:49:16 GMT
Valve Guides have been bulleted for gas flow. but its hard to tell the valve sizes with a tape measure you really need to remove the valves and measure them with a vernier caliper. Also I would clean the blue paint flecks out of the inlet ports before tou start it up. Chambers are the kidney bean shaped recess the valves are sunk into. N |
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Post by Deleted on Oct 7, 2009 19:13:21 GMT
we do this week at let you know thank you
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Post by mccarefree on Oct 28, 2009 19:42:38 GMT
That looks like a nice head and I'd agree with Paul's assessment that the 17.0 is the cc volume of the chamber but I'm not sure 0.130 is the skim. Rule of thumb is 0.012" skim reduces chamber volume by 1cc so a 0.130 would represent almost 11cc off the chamber volume leaving a volume of 10. Even allowing for some re-shaping of the chamber this is not likely. Even a 17cc chamber volume will give a very high compression unless you use a deeply dished piston. I'd guess that 4744 is the engineer's serial number for that actual head.....be interested to hear the end of the story. Cheers, Martin.
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