Hi Everyone!
Regarding the valve adjustment procedure, the base circle on these camshafts is Not really a circle at all. This means that you cant really set the valves with the lobe pointing randomly away from the follower (ie the 90deg method). It needs to be in a specific position.
I set mine one lobe at a time with the lobe pointing at the oil squirter tube.

I would suggest that you prove to yourselves my statement about the base circle not really being round, and it is very easy to do. First, Set the valve clearance with the lobe pointing at the tube. Then rotate the cam untill it is pointing Straight up or about 11 oclock. Check your valve clearance again! It will be quite different! Then turn the cam slightly past the tube, say 2 oclock. Once again, check the clearance, and it will be different. Please don't just take my word for this, but rather actually do the experiment next time you set the valves. I wish the FSM was a little more specific about EXACTLY what position the lobe should be in to set the clearance, but, sadly it is not.

I hope this helps!
Cheers!
Chris

OR they could just assume that the Factory Shop Manual specifies a certain procedure for a good reason... LOL

You are correct, on a worn cam there will be various degree wear that is why I said "on a cam that is not damaged" the reason the FSM doesn't specify position is because when the car is built there is a perfect base circle for the cam...

Help? I did not ask for help. Maybe you are confusing me with someone else? We were discussing why a taper was used on the PS pump and you go on a rant that I do not believe in the FSM and that I have not read the same books you have been reading.

Whenever I check valves clearances, I always check a few at different points of the base circle (valve pointing up or at the oil rail) and found no difference. This was with cars in my sig. Small sample size but data nevertheless.

With proper clearance, the base circle never makes contact with the follower. A cam base circle would have to wear unevenly to become an imperfect base circle. Does that always happen with tight valves? You would think it would wear evenly and maintain a perfect base circle.

You asked me why a taper was used on the PS Pump.

and I said I do not know specifically about that..but that in machine theory books I have encountered... one use of the friction taper involves protecting the tool from unexpected problems in the material being dealt with... as an example you can see that a set of Silver and Deming drill bits used by the typical post drill of old times.... all the drill bits had the same size shank.. and a flat on one side... this fit quickly and accurately into the hole in the drill shaft... which had a lock bolt to keep the drill bit in place... a fast and accurate change of bits was thus accomplished..
BUT... if you hit something hidden in the drilled item... it broke the drill bit... or stripped cogs from a gear... or burned a flat on the drive belt...
Most people who need help do not realize they need help.

Here is one possible guess as the the thinking of the MB engineers.... they saw the ps pump as something which could lock up... and ruin the belt driving it... and did not want the ps pump to be an Achilles Heal in terms of the car making it home... or to safety... as the car can be steered ( with great effort )without the power steering pump working...
So they put a emergency slip clutch into the drive line of the PS pump.

I've never heard of anything that's under spring tension under varying loads like a cam to wear evenly...

So, with proper lubrication, the cam base circle should remain perfect even with tight valves?

If the tapers spin relative to each other, both halves are ruined. I'd rather the belt slips then to ruin 2 expensive pieces. A taper is used in machinery for repeatability and quick change, not to protect the work. Are you forcing help on those who are not asking for it? :D

It is ok if the tapers are ruined..
the bigger objective is the safety of the people in the car.

There is a new safety device available on some table saws... it will stop the blade so fast if your finger touches the blade that very little injury will occur...
but it pretty much destroys the table saw and the emergency shut off equipment..
You have to be able to sort out your priorities in life... some people never do.

... that is precisely opposite to what I said...

I saw that ...and started to say that...
but he appears to be upset by anything I say... so I refrained.....LOL

OK, I went back and read your post again and note that I read "evenly" as "unevenly". Typically, how uneven is the base circle wear? I observed no uneven wear on the 3 cars in my sig. What are your observations?

none of the ones I've serviced had any uneven wear either. I'm guessing all the ones I've serviced had regular adjustments, and never had base circle contact.
I have read numerous posts from members that have found their cams to have different clearances at different parts of the base circle. they must have had cars with excessive Oil change intervals, or extreme infrequent adjustment of the valves, or both...