Head dis assembly-rocker shafts not budging

[ceylove]

I was given a "rebuilt" head as a band aid fix. I don't trust that the guides, valve seals, are right or still fresh, it's been on the shelf a long time and also, I was told everything else in the head was put back in "as is" I'd like to get a good look at the seats, valves, springs, etc and maybe have more work done on it. I've loosened the valve adjustment nuts and removed the locking plate at the end of the head but still the rocker shafts are tight in the head. I've buddged them a bit tapping on the end of the shaft that protrudes but once it's flush my next move would be a drift pin same size as OD of the shaft.

I don't want to damage things, the shafts usually come out easier than this on other motors. Any tips?

[TobyB]

I've found that 3 things tend to bind the rockers-

sludge,

head warping,

or burrs on the shafts.

It's OK to drift the shafts out, but make SURE you use something that's

almost the same size as the shaft, and has a perfectly flat end.

a dead- blow hammer helps, but do your darnedest to not mushroom the

shafts.

Check for burrs- it's easy to file them off, as the shafts are soft. Just slide the

rockers out of the way, and you can feel the high spots.

New shafts are worth it, as are rockers (www.fap99.com)

hth,

t

[viali8]

fap99.com rules!

I have been buying parts from them for years. Great Prices!

[allbim]

Before you do anything else, check the head with a straightedge to make sure it is not warped. If it is warped, forget about machining it, because the cam bearings will no longer be aligned. If it is straight, then you should remove the camshaft first. This requires a special tool to compress all the valve springs at once. Once the cam is out, there will be no more side force on the rocker shafts and they should come out easily unless, like tobyb say's, the head is warped, or the rocker shafts are burred or sludge (varnish) coated. If you mushroom the end of the rocker shafts even the slightest amount, you will be in trouble. I usually use a soft aluminum or plastic rod to drive out the shafts. If everything is pefect you can just push them out by hand. Good luck.

[john_a]

I've loosened the valve adjustment nuts and removed the locking plate at the end of the head but still the rocker shafts are tight in the head. I've buddged them a bit tapping on the end of the shaft that protrudes but once it's flush my next move would be a drift pin same size as OD of the shaft.

I don't want to damage things, the shafts usually come out easier than this on other motors. Any tips?

Just want to check that you removed ALL the clips that hold the washers that locate the rocker arms, opposite the rocker springs ? Many a head has an extra indent from someone leaving one behind as they first whack the end of the shaft & see it does not move far.

Look at #20 here:

http://www.realoem.com/bmw/showparts.do?model=1374&mospid=47315&btnr=11_1183&hg=11&fg=25

I have a few drill rods from the industrial tool store to use as drifts (used to cost about $5 each, probably double that as steel prices have shot up.)

These are available in any diameter, so get one just smaller than the rocker shaft (is that 14 mm?) and the length is 3 foot. A bit longer than ideal, but that's how they come.

For stubborn shafts, I put the head against block of wood, up against a solid stop, and tap the shafts out. Your block of wood protects the head, and provides room between the head & the stop (brick wall, or whatever) for the shafts to come out.

Watch that the working end of the drill rod does not mushroom out, dress it back to shape on a belt sander as needed. If you had a lathe, you could cut the drill rod down a bit, and turn a small tip on the end that could nest inside the hollow rocker end. I've used them without lathe modification for years, have two main sizes for M20 & M10, as the shaft diameters are different.

Check for clips on the shafts first! Slide the rocker arm over against the spring, then you can move the stepped washer which hides the circlip.

[ArdenK]

My favorite "Drift" is a standard size drum stick, it fits the hole just right. Be careful and watch that splinters don't go where they don't belong. Usually the end you hit with the hammer splinters, when it does, trim it with a saw and keep on going.

hth

[ceylove]

Thanks all for the great tips and help. This head was "fresh" from the machine shop, still with the purple dye around the seats, etc but I have no idea what machine shop or what year? so I checked it for thickness and warpage. I was unable to slide a .002 feeler between the straight edge and surface of the head, so I think I'm OK there.

Yes, I did not know about the clips and luckily found out about them before I started "drifting" Not having the fancy spring compression tool that compress all at once, I made a tool to rotate the cam-an aluminum bar drilled to accept 2 bolts to go into the cam gear hub.

Once the clips were off the rocker shafts-tap tap with a 5/8 wooden dowel, cut to different lengths. I used shorter ones at first and longer ones as needed, gently rotating the cam as needed to ease off the rocker faces as I went.

Once the rocker shafts were out, of course the cam came out almost on it's own. Again, the FAQ talked me down on this one, Thanks a bunch!

[ceylove]

(nt)

[TobyB]

One thing I've found-

if the cam turns freely and the rocker rods slide in and out

without much push, the head's not very warped. It may need a cleanup

cut, but that's no biggie.

The real warpage problem is that a warped head will bind the cam up,

the bearings will gall/fail, the cam will break, and then you're done.

Sounds like you have a good one, tho.

\

t