In Reply to: Seeking e28 M5 Head Rebuild Advice posted by Greg on January 15, 2000 at 18:33:00:
I am not aware that it is possible to buy new valve guides for the M5/6 head. BMW certainly doesn't sell them. Instead they sell valves with oversize stems. You ream out your existing guide to fit.
If you join mformation (http://www.bimmers.com/m5m6/) then you can search the archives and you'll find tonnes of info.
: Any technical caveats or performance suggestions in having a M5/6 head rebuilt? Aside from careful machining for replacement of worn guides by a qualified M-head specialist, are there other weak or troubled areas to consider? Any suggested shops?
: I'm planning on removing and installing the head myself. How difficult will this be? I've rebuilt a few low-tech engines (as in MG), and serviced my 535, but am not familiar with the M5. Pulling the head seems straight forward enough. Are there any caveats in dealing with install/removal of components?(intakes, etc). Resources?
: Also, has anyone used a Metric Mechanic M5/6 head? If so I'd appreciate hearing from them. Finally, are the performance increases from using high flow ported heads accurate? I've heard that with the high flow head, a JC chip, and a decent exhaust you are in the 300-320hp range?
: Greg Kovecses