I bought a cylinder head, supposedly off an S. the idea was to get someone to port it for me who knew what they were doing. How can I tell from looking at it whether it was from S or not? I read that the the exhaust valve material is supposed to be different. How can one tell by looking at it or measuring?

 

Yes, the valve material is different but, other than that, everything else is the same.

 

everything else cant be the same, the CR of a MC is 10:1 and an MCS is 8:1, the head has to be different, unless the rods are different too.....

 

I believe the crank, rods and pistons are different.


Bill

 

The head it self is the same, valve material are different, rods, pistons and
crank are of a inferior materials, good for low hp applications but anything over 150hp and it's byebye

peter

 

how do you feel about bumping up the CR of an MC motor Peter? I was thinking about it since we have all the machine shop tools on hand now, it might be a good project....

 

I think it would be a chancy proposition, knowing that you already have
a 10:2+ CR. I would start with the crank have it polished, balanced and nitrated, forged conrods, pistons will allow you to push the issue with confidence. Or you can just jump in feet first and hope nothing will expire
or dissintegrate (It will).....

peter

 

what I mean is, looking at it, is there something which would tell me, for instance, that the valves in it are MCS vs cooper? Like a marking, a vave stem size, a neck down, or something?

 

According to the paper that describes the differences between the two engines:

http://www.mini2.com/pdf/mcs_powertrain_us.pdf

The valves of the MCS have a smaller stem in the valve port to allow for more gas flow, and the rocker arms are beefed up to handle the stress of higher revs.

The MCS has forged rods, forged crank, and piston cooling jets.

The pistons are Lenticular (Dished out tops) which reduce the compression ratio from the MC engine.

The photos for that article are in the German version:

http://www.mini2.com/pdf/mcs_powertrain_de.pdf

I have never seen the head or the valve train.

John

 

What I mean (again) is: I'm looking at the head in front of me. It's got the casting, it's got the valves, it's got the rocker arms, it's got .... Now, is there something I can look at or touch, on or around or connected to the head which is in a box in front of me, that will tell me that it is an S or cooper head. Like the dimension of the valve stem at the end is X" for S and Y" for cooper, or the rocker arm has the marking xyz on it if it is an S. I don't know what else to say to clarify my question. I don't want to hand off the head for use on an S if it has the cooper valves. There's gotta be a way to tell, by someone who's seen them both.

Is there anyone who has seen them both and knows fur sure?

Thanks

 

From the description I have read, the valve stem will be narrowed in the exhaust port, but stock size in the guide. If that is true you should be able to see the taper of the valve stem in the port when the valve is open.

Seeing it would indicate it is an MCS head. Not seeing it may just mean it is not visible, or it could mean it is an MC head.