Hello all,

First time poster here, please I need some help with technical data for my engine, really appreciate if anyone can help.

I'm rebuilding the cylinder of my R56 Cooper S (2007) , All valve guides are very loose so I'm replacing all of them, I've bought all valve guides but they all come with fixed inner diameter of 5mm.
Valve stems are 4.95mm for both inlets and exhaust so that give 0.002' clearance for both inlets and exhausts.

I understand exhaust valve generally needs extra clearance, I'm struggling to find the exact valve guide clearance details for this engine (N14B16A) so I can order correct sized reamers.

The reason I'm rebuilding this myself is I'm unable to find a local machine shop at the moment, both shops I knew have been closed and due to Covid lockdowns only essential travel are allowed so I'm unable to drive around and ask people who might know a place. Otherwise I would leave this job to a professional.

I found technical data for R53 engine here
http://wtxmc.org/MiniCooperDocs/ENGINE%20TECH.pdf


Above data is for a valve with 6mm stem , R56 head valves are 5mm , so I wonder if above values get slightly scaled down for R56?

It's a stock motor used for normal street use, nothing extreme.

Thank you

 

From newtis....

 

Wow thank you!

Those values seem to super tight, glad I came here otherwise I would have reamed them slightly larger

Again can't thank you enough.