12 replies to this topic

[Trail of Dead]

Hey guys! I have a 1982 998cc Mini that I need to restore as soon as I get the right tools. The questions I have though are regarding a 997 Cooper head that I have. Will this head fit the stock 998cc engine in my Mini? According to this the engine in my mini is a A+ 998cc......

If this head would fit would I notice any significant gains in performance? I've tried to search both here and using Google to find the answer no avail. Is a 997 Cooper head rare? I'm sorry if I sound like a dunce regarding these cars....but like I keep raving on about I am a Yank and really don't know that much about the Mini....not nearly as much as you guys do. I'd like to use this head if it would be worth it, also I AM planning on swapping to a mild street cam and some roller rockers as well as stainless valves if that helps anyone. I was thinking of going with a Nitrocaburised (sp?) crank as well.....does this mean it is a forged crank? Basically I'd like to incorporate this head into a performance rebuild of the engine and attain at least 50 horse out of this little engine. It has to be possible, my Yamaha Banshee back home has 78 horsepower and it is only a 2 cyl, 420cc!

[Trail of Dead]

bizzzummppp!!!!

[Frog]

I take it the casting you have is a 12g202, this would be a 997 casting these heads were also fitted on morris minors, they have slightly larger ports compared to the standard 998 head but are not as good as a 12g295 (998 cooper head). I used to run a standard 998 A+ engine with a 997 head on & a mild road cam it went really well. Nitrocarbonizing the crank is just a modern term for toughening it pretty much like the old forged cranks. If you rebuild it correctly & get it set up properly it should be a good little engine. You don't want to use 1.5 rockers though as they are a nightmare on small bore engines unless you are going racing. I would say as you already have the head use it, you could always upgrade later if you want a little more power.
Hope this helps.

[lrostoke]

If the head is unmodified then you will need it skimming to raise the compression ratio..

The combustion chamber is slightly larger on the 202 and 295 heads than the standard 998 head.

[bmcecosse]

Yes- would need to skim the head by ~ 60 thou to get a decent compression ration. It is a slightly better head - but nowhere near as good as the 12G295 head - as others have pointed out!

[miniman_78]

Erm, Frog,
Aren't 12g202 heads from the 1098? Thought 997 heads had casting number 12g185

[Nightrain]

Erm, Frog,
Aren't 12g202 heads from the 1098? Thought 997 heads had casting number 12g185

The ONLY mini to have a 202 when it left the factory was the 997 cooper, by the time the 1098 found it's way into the mini it had a standard closed chamber head.
12G185 was the early Cooper S Head.

[miniman_78]

At home I have my 3e 1098 engine and it has a 202 head like my previous ones. So that means its the same head as the 997? I gave 2 of them away a few years ago for almost free. Think I won't do that again... Going to keep it for a future 850 project I think.
Googled around and found for the 202:
"The 997cc Cooper cylinder head was also fitted to varios standard tune 1098cc engines, including the single carburetter Austin/Morris 1100 and the 1098cc Minis, plus the high perfomance 948cc Austin Healey Sprite Mk 2 and MG Midged Mk1. For identification purpose the casting number is 12G202 and the inlet valves are 1 5/32" (29.4mm) diameter. The chambers are 26,1cc volume"
The 1100 also had the castings 12g206 and 12g295 and both with 28,3cc chambers.
The 12g185 were fitted to the early 997cc but with 1 1/16" diameter inlet ports and 24,6 cc chambers.

Edited by miniman_78, 14 July 2009 - 01:23 AM.

[Trail of Dead]

Thanks for the info chaps! I think I am going to use this head then, but as Frog mentioned I wouldn't be able to run roller rockers? Darn! I really wanted to run a set. Oh, and yes it is a 12G202 and it's in pretty good shape. It's not all rusted up as it's covered in a bunch of oil and grease....should clean up easily. Might sound like a stupid question but do they even make stainless valves for these cars?

[mini7boy]

Thanks for the info chaps! I think I am going to use this head then, but as Frog mentioned I wouldn't be able to run roller rockers? Darn! I really wanted to run a set. Oh, and yes it is a 12G202 and it's in pretty good shape. It's not all rusted up as it's covered in a bunch of oil and grease....should clean up easily. Might sound like a stupid question but do they even make stainless valves for these cars?

I really don't know much about the small-bore A-series engines, but I know that genuine 997cc engines are very rare. If your 997 cylinder head is one that was either available only on a 997 engine or is relatively rare and used on other engines besides the 997, I would certainly make the effort to first make sure exactly which casting it is. Then I would try to find out if the head is valuable to someone who has a 997cc engine and wants to have a 997 head for reasons of authenticity. You might find that this particular head you have is worth serious money and you can sell it for enough money to buy a well-prepared 998cc head from one of the professional head porters. In that way, you'd end up with a much better head than the 997 you now own.

It would be a good idea to do your homework before you have anyone start machining on this head. If it is truly rare, you might be able to get a really good cylinder head out of the deal if you sell this head off in its most authentic condition rather than modifying it into something that the authenticity obsessed will turn up their noses at.

[Trail of Dead]

Thanks for the info chaps! I think I am going to use this head then, but as Frog mentioned I wouldn't be able to run roller rockers? Darn! I really wanted to run a set. Oh, and yes it is a 12G202 and it's in pretty good shape. It's not all rusted up as it's covered in a bunch of oil and grease....should clean up easily. Might sound like a stupid question but do they even make stainless valves for these cars?

I really don't know much about the small-bore A-series engines, but I know that genuine 997cc engines are very rare. If your 997 cylinder head is one that was either available only on a 997 engine or is relatively rare and used on other engines besides the 997, I would certainly make the effort to first make sure exactly which casting it is. Then I would try to find out if the head is valuable to someone who has a 997cc engine and wants to have a 997 head for reasons of authenticity. You might find that this particular head you have is worth serious money and you can sell it for enough money to buy a well-prepared 998cc head from one of the professional head porters. In that way, you'd end up with a much better head than the 997 you now own.

It would be a good idea to do your homework before you have anyone start machining on this head. If it is truly rare, you might be able to get a really good cylinder head out of the deal if you sell this head off in its most authentic condition rather than modifying it into something that the authenticity obsessed will turn up their noses at.

Point taken! Hmmmm....well I don't have the proper tools to measure anything it. I'll take a look at it later on and see what casting numbers I can find, maybe one of you guys is an expert and could possibly tell me what they mean? I have a webpage bookmarked that gives me a specs on it but the only casting number it mentions is 12G202.....I'll see what else I can dig up.

[Nightrain]

"The 997cc Cooper cylinder head was also fitted to varios standard tune 1098cc engines, including the single carburetter Austin/Morris 1100 and the 1098cc Minis

It was never fitted to a 1098 mini, it had gone out of production by the time the 1098 found it's way into the mini.

[Trail of Dead]

I first found out "what" the head for used for by stumbling upon this.