I am trying to remove the fuel rail from my M60. According to Helms, it appears the injectors should pop out still attached to the rail. I removed the 4 retaining nuts for the rail, but nothing budges. The injectors are probably original, and I know they have not been out in the last 100k miles.

Any ideas on loosing them?

They're held in by an O-ring top (into the rail) & bottom (into the intake manifold). Be sure you have all of the retaining nuts/bolts/screws out of the fuel rail, then carefully pry/wiggle/pull the rail off of the injectors.

Replace all O-rings & when installing them, lightly lubricate them with Vaseline, or silicone grease.

So I remove the retaining clips at the top of each injector and pull the rail from the injector?

When reinstalling, do I just reverse that or do I need to remove each injector, and put into rail, or leave injectors where they are?

Once the retaining clip is out, the rail should pull free (with a bit of prying). Don't be surprised it they pull out of the manifold instead. No problem, just replace that O-Ring as well

On installation, depending how access is for installing the clip (they're a pain sometimes)it might be easier to put the injectors in the rail, install retainers & drop the assembly in place. Be sure to clean the pocket in the manifold so you don't get any junk on the injector as it slides in. Note that the clip slides into a small groove in the injector body, this ensures they are inserted to the correct depth.

Well, that worked. I have not decided if I will pull the injectors from the manifold or not before reinstalling.

Now that I am looking down at the valves I notice they are filthy. I plan on soaking the manifold to get rid of the gunk, but is there anything I should do with the head? I pulled this out to replace the vent. I don't know if a bad vent caused a lot of oil to get pulled into the intake or not, but it is caked on.

might consider having the injectors cleaned & flow matched. Several companies that specialize in this.

www.lindertech.com is a good one. He can send you a set already rebuilt, will cost about $150 for a set. Drop them in with new O-rings already installed. Good guy, did me right on several occasions.

Deposits on the valves are a common problem with BMWs. The old sixes were notorious. There are valve cleaners used by BMW, Lubro Moly's ventil sauber, seafoam, etc. A search of the old 5 series or 7 series boards should dig up some recommendations