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Looking for some help from the E30 community… 
1987 325is
305k on the engine
Broke a rocker arm (#4 intake) at a recent BMW CCA DS.
Slid out the rocker arm shaft and #6, 5, 4 rockers.
How do these surfaces look to you? Something I should be concerned about? Replace them all? Is this normal?
(yea, yea, I know I should be thinking rebuild with 305k on the engine, just wondering if this engine will give me another 10 track days or is likely to grenade at the end of my driveway!)
Stick a fork in them…they are done:laugh:
Don’t forget to blueprint the new rockers. And you probably want the cam blueprinted also. CB
Might want to look carefuly at cam lobes too. Time to start using an oil that is high in zddp. Mobil1 15w50, Valvoline VR1, or any Redline and AMSOIL oil will do nicely.
That being said, at 305k mi, that motor did honorable service.
I guess I’m going down the “new rocker” road.
Cam lobes felt OK to me - hard to tell for sure.
I have a 160k engine waiting to go in - maybe I should do the whole swap or at least the head?
Not even sure what that engine looks like, though. At lease with my engine, I know it’s been maintained well (previous owner was my father in law).
How would one tell what kind of shape the cam is in? Flat spots at the top of the lobe?
Look hard at the lifting side of the cam lobe. That would be on the driver’s side. The surface of the lobe should be pretty close to mirror smooth. Even minor degradation would be bad. From what I’ve read, once the cam lobe surfaces start to go, they go pretty fast.
If you’re going to be tracking the car, the cam needs to be in really nice shape. High rpm means high loads on the lobes. For a DD tho, you might be able to get away with a cam that is less pristine.
cwbaader, the first guy that responded, knows a helova lot more then me tho.
The cam lobes are mirror smooth - no pitting like the rocker surface shows in the pics. Not sure if they are flat spotted, though. I can feel the top of the lobe, and it doesn’t feel symmetrical (if that makes sense) - like it falls off quicker than it ramps up.
Car is used only for track - it was on the way to becoming a SpecE30 (gutted, roll cage, SpecE30 suspension), but I’ve realized I won’t be able to commit to Spec E30, so it’s a open-track day and DE car at this point. Not competition racing, unless you consider trying to keep up with fellow E36/E46 Bimmers!
With a spare engine sitting at my work, I’m just looking to get a season or two more out of this engine - maybe 8 track days per season. When it’s really dead, I’ll do the swap. Not sure if I should consider it “really dead” at this point or not. I was just going to swap the broken rocker and get it rolling again.
Based on your guys’ input, I guess I’ll swap all the rockers - at lease on the intake side. I’m guessing exhaust side is going to look the same, though. Bummer.
It’s pretty easy to swap the motor on a track car. I’d put in the low mileage motor and then consider leisurely rebuilding the 305k one.
Otherwise you’re going to pull your head off and apart…The other rockers need inspecting. Then put it all back together. And then do this all over again next year for the engine swap. It’d be half as much effort to do the engine swap now.
If I can do an engine swap, anyone can. But, ahhh, try to avoid doing it monthly.
The cam lobes are asymmetrical. At that mileage, you should pull the cam and mike each lobe…you will probably find as much as .010" variance, that is why I suggested a blueprint. Except for the cam and valves, everything in the head is probably junk. You will also need valve guides and the springs checked … you probably broke the rocker by over revving or floating the valves because of weak springs. That requires the valves to be checked for bending. On a 300k or a 160k motor, you should be looking at a complete build as the bearings will also be toast. Getting by on the 160k motor will be iffy at best. At least get a “T” sump pan. Chuck
Chuck, how are cams modified during the blueprinting process? I never really understood how that works. I mean any problem found on a lobe is going to be a matter of missing material. So how is the missing material restored? There’s no way to grind a lobe back into spec that I can imagine.
They are not modified, they are returned to the stock size/shape. The smallest lobe is chosen and trued, the remainder are then ground to that size. Depending on cam size, you may need to use oversize eccentrics for adjustment. The last two I had reground did not need them. In really bad cases, they can re weld/regrind the cam to original size. Chuck
I removed the rod bearings from my 300k motor to inspect them last fall and they “looked” decent. Only one had a bit of visually-noticable wear (#6). Replaced them with new while I was down there along with a new oil pump.
I guess I’ll get the replacement motor on an engine stand and see if I can’t tell what kind of shape it is - pull the valve cover/oil pan and have a look. Maybe pull the rod bearings…
Sounds like I better buy the wife an ice scraper - her car’s gonna be in the driveway for a while. Sure… she’ll complain a bit, but I surely can’t have my DD sitting outside in the winter! 
cwbaader wrote:
It seems to me that any lobe that is ground has to end up smaller. I’ll have to bring this up next time I see you. Maybe if we draw something on paper I can be made to understand.
OP: Do a leakdown test on the spare motor. It’s very easy to do when the motor is out of the car. There’s a DIY on my website. If it does ok on the leakdown test, I’d just go ahead and put it in without screwing with the bearings. Unless it was mistreated, the bearings on it ought to be in pretty good shape.
Just put it in with a crankscraper and keep it 1qt overfull. And if you are the obsessive type, you can jump on my bandwagon and put in an Accusump.
As far as the valve opening is concerned it is only the difference in the minor and major diameters that determines how far the valve opens. When a cam is blue printed the smallest lobe determines the major diameter for all lobes. The regrind of that lobe removes material from the minor diameter and cam faces to return that lobe to spec profile. Then all other lobes are ground to match.
As long as there is enough adjustment to set valve clearance, those valves will work the same as if a new cam had been installed. Okay, for the picky there can be a very slight difference as a result of the rocker angle change. But that isn’t enough to affect anything.
Scott, IMO advising someone to overfill their crankcase is really bad advice. Keep in mind some people here may actually think you know what you are talking about. 
Resurrecting my old post…
I left the top end of the engine somewhat disassembled this winter, and jumped back into it today. I decided to do the half-a$$ job of replacing just the rockers. Decided to look at the camshaft, and thought I’d post some pics.
Looks like I’m probably wasting my time with this old engine. She gave a good 305,263 miles to my father in law any myself! (I racked up about 4,000 miles - 1.3%)
Looks like the cam is toast, but the top end looks pretty clean to my untrained eyes, eh?
Obviously frequent oil changes…clean engine.
You have the head bolts that break.
Cam can be reground per my earlier post. Change engine oils to one that has zink, etc. … wear there indicates lack of lubricity of the oil. CB