Head question,

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

Did the 1100 heads have double valve spring set up ? Fitzy

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)

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.

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

TurboJo wrote:

8<

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

TurboJo wrote:

8<

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.

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

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

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

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

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

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

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

22.7 should be the chamber volume, 22.7cc. I haven't come up with a good explanation for the 90 yet.

Cheers,

Kelley

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.

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

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

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