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
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.
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
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
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.
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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