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Car Forum / MINI / December 2005

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Head question,

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Fitzy - 26 Nov 2005 15:00 GMT
Can any one identify this cylinder head please, 12G202
I came across it in a shed, with a full set of valves, and double valve
springs, its been ported and polished,
will it fit on a 1000cc engine,
one broken stud in T/stat housing,
Thanks
Fitzy
** - 26 Nov 2005 15:29 GMT
Hi, Fitzy,
It's an 1100 cc head. It will fit a 1000 cc engine, but the compression
ratio may be a bit lower.

keith

> Can any one identify this cylinder head please, 12G202
> I came across it in a shed, with a full set of valves, and double valve
[quoted text clipped - 3 lines]
> Thanks
> Fitzy
Fitzy - 26 Nov 2005 17:52 GMT
Did the 1100 heads have double valve spring set up ?
Fitzy

> Hi, Fitzy,
> It's an 1100 cc head. It will fit a 1000 cc engine, but the compression
[quoted text clipped - 9 lines]
>> Thanks
>> Fitzy
Tim - 27 Nov 2005 09:21 GMT
is possibly either a after market set of springs been fitted or it could
possibly be a Cooper 997 or an MG 1100 head. Some of the last of the 997's
did come out with the 1100 casting. More likely to be a MG head though.

> Did the 1100 heads have double valve spring set up ?
> Fitzy
[quoted text clipped - 12 lines]
>>> Thanks
>>> Fitzy
Fitzy - 28 Nov 2005 07:51 GMT
I am tempted to fit it to my City E after overhauling it,
will it make much difference,
Fitzy

> is possibly either a after market set of springs been fitted or it could
> possibly be a Cooper 997 or an MG 1100 head. Some of the last of the 997's
[quoted text clipped - 16 lines]
>>>> Thanks
>>>> Fitzy
Paul Prescott - 28 Nov 2005 11:15 GMT
> I am tempted to fit it to my City E after overhauling it,
> will it make much difference,
> Fitzy
I thought I read somewhere recently that the 12G202 was nearly as good as
the 12G295?
Does it have any stampings anywhere? I have a 12A1456 with CAHT88 24.0
stamped on the upper surface just behind the heater outlet.  I believe it's
an unleaded stage 3 with 24cc chambers, from Mini Spares, but it appears to
be based on a 850/948 casting.  It's got 12G295 sized valves, double springs
and the ports are well opened up. I have't tried it yet, but with the right
induction, it should make quite a difference; need to calculate the
compression ratio first.  Could be worth looking for similar markings on
yours, given the double springs and modded ports, and also worth checking
the chamber volume...
Paul
Fitzy - 28 Nov 2005 14:13 GMT
In the casting under the rocker shaft is,
23453.......MOWOG........12G202... and stamped next to the heater outlet is
3225    22.7    90
any ideas
Fitzy

>> I am tempted to fit it to my City E after overhauling it,
>> will it make much difference,
[quoted text clipped - 15 lines]
> the chamber volume...
> Paul
Paul Prescott - 28 Nov 2005 14:50 GMT
Could be that 3225 22.7 90 is a head modifier's identification mark, but,
sorry, I don't recognise that one. the 22.7 could be the chamber volume....
3225 couldn't be the valve sizes, could they (32mm inlet, 25mm exhaust),
although 32mm sounds a bit too big for a small bore valve...
Paul

> In the casting under the rocker shaft is,
> 23453.......MOWOG........12G202... and stamped next to the heater outlet is
[quoted text clipped - 21 lines]
> > the chamber volume...
> > Paul
Fitzy - 28 Nov 2005 17:17 GMT
Thanks for the input Paul,
I think I will lap in the valves, a set of new seals, remove broken stud,
and bang it on ,,,,,
Fitzy

> Could be that 3225 22.7 90 is a head modifier's identification mark, but,
> sorry, I don't recognise that one. the 22.7 could be the chamber
[quoted text clipped - 33 lines]
>> > the chamber volume...
>> > Paul
Kelley Mascher - 28 Nov 2005 20:38 GMT
The 12G206 / 12G295 used a 31mm inlet so this isn't out of the
question. In other words, I think your right about ID marks.

Kelley

>Could be that 3225 22.7 90 is a head modifier's identification mark, but,
>sorry, I don't recognise that one. the 22.7 could be the chamber volume....
[quoted text clipped - 8 lines]
>> any ideas
>> Fitzy
Fitzy - 29 Nov 2005 11:12 GMT
I have just checked the valves,
32m inlet and 25m exhaust, looks like you where right,
seats are pitted to the point of a recut, valves are ok though,
Fitzy

> The 12G206 / 12G295 used a 31mm inlet so this isn't out of the
> question. In other words, I think your right about ID marks.
[quoted text clipped - 14 lines]
>>> any ideas
>>> Fitzy
erik fishead - 07 Dec 2005 00:05 GMT
>I am tempted to fit it to my City E after overhauling it,
> will it make much difference

Yes, but it depends on how it feels with the standard head.

I put a 12G202 from a Clubman saloon on my 84 Sprite. No rolling road or
anything, just done and tuned on the side of the road. No noticeable
increase in power but there was a noticeable increase in torque.

After the head swap it would beat a lightly kevved 2.0i Sierra to 60. Not
bad for a 100,000 mile 998.

erik.
Fitzy - 08 Dec 2005 20:42 GMT
> >I am tempted to fit it to my City E after overhauling it,
>> will it make much difference
[quoted text clipped - 9 lines]
>
> erik.

for a 998 it feels ok and drives ok at the moment  ,,, but I am tempted to
fit this head just to experience the difference, I am not in to speed,  if I
get more torque then I will be happy,
Fitzy
MiNiFrEeK :) - 26 Nov 2005 19:29 GMT
Good if you want to "turbo" it !!!

Just slap it on and watch the thing flyLOL , I put a 1300 head onto my 1000
block and it just flies now (60+bhp from -50bhp)

> Hi, Fitzy,
> It's an 1100 cc head. It will fit a 1000 cc engine, but the compression
[quoted text clipped - 9 lines]
>> Thanks
>> Fitzy
TurboJo - 27 Nov 2005 22:53 GMT
12G202

997 Cooper, Austin/Morris 1100, MkII Midget/MkIII Sprite

Inlet 1-5/32" Exhaust 1" Chamber volume 26.1cc

Don't think these had double valve springs as standard.

> Can any one identify this cylinder head please, 12G202
> I came across it in a shed, with a full set of valves, and double valve
[quoted text clipped - 3 lines]
> Thanks
> Fitzy
SpyderMan - 27 Nov 2005 22:45 GMT
hi,

I think the MkII Midget / MkIII Sprite had double valve springs.  The
9CG engine (948cc) Spridget heads did, where the 9CC (948cc Sprite MkI)
heads did not (did they use the same heads??) .

Terry Horler's truly excellent Original Sprite and Midget book seems to
back me up on this, so it's not just my alcohol addled mind playing
tricks :)

Best regards,

Phil

> 12G202
>
[quoted text clipped - 3 lines]
>
> Don't think these had double valve springs as standard.
8<
SpyderMan - 27 Nov 2005 22:46 GMT
hi,

I think the MkII Midget / MkIII Sprite had double valve springs.  The
9CG engine (948cc) Spridget heads did, where the 9CC (948cc Sprite MkI)
heads did not (did they use the same heads??) .

Terry Horler's truly excellent Original Sprite and Midget book seems to
back me up on this, so it's not just my alcohol addled mind playing
tricks :)

Best regards,

Phil

> 12G202
>
[quoted text clipped - 3 lines]
>
> Don't think these had double valve springs as standard.
8<
Fitzy - 04 Dec 2005 00:49 GMT
Thanks to your help
we have ascertained that the 3225 is the valve sizes,
does any one know what  the  90  22.7   represents this is stamped on this
head near to the heater valve,
Thanks
Fitzy

> hi,
>
[quoted text clipped - 18 lines]
>> Don't think these had double valve springs as standard.
> 8<
Kelley Mascher - 04 Dec 2005 18:29 GMT
22.7 should be the chamber volume, 22.7cc. I haven't come up with a
good explanation for the 90 yet.

Cheers,

Kelley

>Thanks to your help
>we have ascertained that the 3225 is the valve sizes,
[quoted text clipped - 25 lines]
>>> Don't think these had double valve springs as standard.
>> 8<
Paul Prescott - 08 Dec 2005 21:09 GMT
With only the "90" left to explain, another thought came to me.  As this is
obviously a highly modded head with large valves and a small combustion
chamber volume (for higher compression ratio), it is possible that the firm
or person who prepared it were into even more extreme products.  This leaves
me to conclude that the "90" refers to the angle of the valves (i.e.
standard, upright). Inclined valve heads used to be the ultimate in 5 port
design, as I believe they flowed slightly better and could take slightly
larger valves. I've never seen one, but often read about them in the past.
The valve was only inclined by a few degrees, but this clearly involved lots
of engineering, reshaping the valve throats and seats, and redrilling the
valve guide holes.  I would guess that a new angle of 87 or 85 degrees could
possibly be achieved.  If this is about right, then maybe their more
traditional products would merely be marked with a "90" to indicate a
standard valve angle.  Hope this makes some sense.  Anyone still using
inclined valve heads?
Paul

> Thanks to your help
> we have ascertained that the 3225 is the valve sizes,
> does any one know what  the  90  22.7   represents this is stamped on this
> head near to the heater valve,
> Thanks
> Fitzy
Fitzy - 09 Dec 2005 23:09 GMT
Hi Paul,
that sounds very possible, I will go with that theory, unless someone knows
different,
Fitzy

> With only the "90" left to explain, another thought came to me.  As this
> is
[quoted text clipped - 25 lines]
>> Thanks
>> Fitzy
 
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