M130 head assembly question (cam towers) - PeachParts Mercedes-Benz Forum

n6mod · #1 04-20-2009, 08:31 PM

I just got the head for my '72 280SE (M130) back from the machine shop, and am reassembling the cam towers and shaft. With the nuts that hold the cam towers to the head just finger tight, the camshaft turns freely (no rockers installed yet). If I tighten those nuts, the cam becomes hard to turn. Is this expected, or is there some procedure for getting the towers torqued down correctly that I haven't found in the book yet?

Thanks,
Zandr

Arthur Dalton · #2 04-20-2009, 08:39 PM

Did they shave the head ???

n6mod · #3 04-20-2009, 08:42 PM

Quote:

Originally Posted by Arthur Dalton

Did they shave the head ???

Yes, they did. Do you think it's no longer straight?

These guys come highly recommended, so I'd have assumed they know what they're doing. I can call them tomorrow and ask them if they straightened the head.

How would I (or they) go about measuring to find out if the towers are still aligned correctly?

Arthur Dalton · #4 04-20-2009, 09:14 PM

They have to straighten the head before milling or the bottom is flat and the top is still warped...so you wind up having to shim the towers or plane the top.
Ask them if they checked it for plane , pre mill....

If it was really warped before they cut it, you will know after you get it running b/c the end cylinders will have more compression than the center ones. They usually warp up in the center, so when they cut , the ends get more cut than the center...which is why they should straighten it first.........along with the cam tower problem it creates.

n6mod · #5 04-20-2009, 09:21 PM

Quote:

Originally Posted by Arthur Dalton

Ask them if they checked it for plane , pre mill....

OK, will do.

BTW, am I doing this right, setting the cam in the towers on the head and tightening, or should I install the towers and then install the cam?

Though, if there's an alignment problem, I don't think the cam will slide in, will it?

Thanks again!

-Zandr

Arthur Dalton · #6 04-20-2009, 09:26 PM

Just see if you can turn the cam as you tighten them down w/o the chain on
you will know when it start to bind,...you may also want to lay the towers on the head w/cam only inserted and see if you can rock the cam on the ends ..if the center is higher by a good anmount, you might be able to feel the difference as you rock the ends ..it should lay completely flat, with no rock. Yo may also be able to tighten the center two and be able to turn the cam, but as soon as you start to tighten the end ones , it will bind if they are too low..then you know where you have to shim...experiment.
I would talk to the shop who did it first..

And you may want to visit the 113 site ..they have all kind of head planning procedures in detail over there..it is a common 127/129/130 job............

n6mod · #7 04-22-2009, 02:44 PM

The head measured straight before any machining, but the top is clearly not straight now. The shop is going to shim the towers for me, but... the frontmost cam journal is trashed.

So, anyone got a cam?

('72 280SE M130.980)

-Zandr

Arthur Dalton · #8 04-22-2009, 02:58 PM

Try JA17 here or 113 group..he has parts and is fair...he will want the cam mumber..

bwostosh · #9 04-23-2009, 11:08 AM

Cams can be repaired by welding and re-grinding, either lobes or bearing journals. I just had one re-ground ($125) by Schneider Racing Cams. If you cannot find a cheap replacement.

Or Call Dennis at 619-421-3254 he has one (dunno the price tho)

n6mod · #10 05-05-2009, 05:29 PM

I'm going the regrind route, but I'm 60 miles from my manuals, and I'm not sure the spec is there anyway....

Does someone have the spec for the #1 (front) cam journal diameter? The whole surface on that journal is pretty worn, so there wasn't a "good" part of the bearing to measure from.

Thanks!

-Zandr

ja17 · #11 05-05-2009, 11:42 PM

Hello Zandr,

Shimming the cam towers is a option. It is described as a acceptable practice in some of the earlier MB shop manuals. Be careful, the front cam support has a oil passage which goes from the block, then up around the head bolt and into the front cam support where it goes into the oiler tube and lubricates the entire camshaft. Make sure the shims do not block the oil passage in the front support.

Some warpage on the top deck can be tolerated. The gauge I use is if the cam sprocket can still be turned by hand after torquing the head, it should be ok (even if a little snug). If it is bound too tight to turn by hand, then shim or mill it.

The original camshafts are nitrited (case hardened). Check to make sure your repaired cam will be hardened or it will not last. The shop should be able to use the dimensions on another good intake lobe for rebuilding your cam. You will need to provide the specs on the valve timing (opening/closing etc).

The cam ID number is stamped on the back end of the cam.

n6mod · #12 05-06-2009, 12:23 AM

Quote:

Originally Posted by ja17

Hello Zandr,

Make sure the shims do not block the oil passage in the front support.

Ah, thanks for reminding me of that.

Quote:

If it is bound too tight to turn by hand, then shim or mill it.

That's what tipped me off to the problem. Once I tightened down the towers, the cam wouldn't turn.

Quote:

The shop should be able to use the dimensions on another good intake lobe for rebuilding your cam.

Actually, it's the front bearing journal, not a lobe, that they're rebuilding. That's the dimension I'm after.

-Zandr

wbain5280 · #13 05-06-2009, 12:31 AM

Wait a minute, the head isn't even installed yet so tightening the offset cam tower bolts is going to bind the cam. The towers must be installed on the head and the head bolts properly tightened.

n6mod · #14 05-06-2009, 12:59 AM

Quote:

Originally Posted by wbain5280

Wait a minute, the head isn't even installed yet so tightening the offset cam tower bolts is going to bind the cam. The towers must be installed on the head and the head bolts properly tightened.

Even though the towers are dowelled to the block? (though I agree that the dowels aren't very tall)

OK, so i need to install the head and torque down the head bolts before I worry about the cam binding. One gotcha is that the valve spring compressor I have (the K-D hook-style tool) doesn't work quite right with the oil tube in place. Should I install the other head bolts with washers instead of the oil tube/valve cover supports?

In any case, the front cam journal is still trashed, so that will need to be rebuilt. Still looking for that dimension.

If I measure the ID of the cam tower to get that dimension, what clearance should I specifiy?

ja17 · #15 05-06-2009, 07:07 AM

Hello,

Yes, If the head has been milled, you should always install the head without the rockers. In this way any binding will be easily detected. The hold down nuts do not supply enough downforce against all those valve springs. Check the cam after the head is torqued. You will need the cam ID number to get the correct diameter of the cam journal. Most are 35mm but not all. I have specs if you can get the number.