Frustration with W123 Valve Adjustment! - Page 12 - PeachParts Mercedes-Benz Forum

funola · #**166** 05-17-2015, 11:12 AM

Quote:

Originally Posted by leathermang

Why don't you share with us your theory on why the Mercedes Factory Shop manual would show as the correct position of the cam lobe the one o''clock position if straight up is just as good ?????????
A bunch of Sadists just trying to rain on your parade... harass you from the grave.... a conspiracy aimed at planned obsolescence.....There has to be some grand theory which causes you to think the VERY specific instructions in the Factory Shop Manual are just suggestions from which you can find an ' easier ' way to do it.

The FSM maintenance chapter for 1985 617 engine says: "measure valve clearance between sliding surface of rocker arm and cam base circle of camshaft by positioning camshaft so that tip of cam is vertical relative to rocker arm."

Since most (180 degrees) of the base circle is machine ground, therefore, there is a range of positions (approx 90 degrees) the lobe of the cam can be pointed to for accurate valve adjustment. Try pointing it vertical next time you adjust your valves, you will agree with me.

Lucas · #**167** 05-17-2015, 11:17 AM

The rocker arms aren't vertical. They are oriented to 1 o'clock.

I always wonder where thr cam stops being "flat." So i just point it directly away.

You could determine how many degrees possible it is flat with a dial indicator.

Let me know you find.

Lucas · #**168** 05-17-2015, 11:19 AM

Quote:

Originally Posted by funola

You don't want it to accidentally trigger when you have the wrenches and feeler gauge in there.

I always unclip positive on the battery. Scared as well that my home made trigger will ground out.

funola · #**169** 05-17-2015, 11:55 AM

Quote:

Originally Posted by Lucas

The rocker arms aren't vertical. They are oriented to 1 o'clock.

I always wonder where thr cam stops being "flat." So i just point it directly away.

You could determine how many degrees possible it is flat with a dial indicator.

Let me know you find.

The base circle is a machine ground surface, it would be difficult to make it not flat, therefore it is flat. As long as you are within +/- 30 degree of the center of the base circle, you will have accurate measurements.

leathermang · #**170** 05-17-2015, 12:10 PM

Quote:

Originally Posted by funola

The FSM maintenance chapter for 1985 617 engine says: "measure valve clearance between sliding surface of rocker arm and cam base circle of camshaft by positioning camshaft so that tip of cam is vertical relative to rocker arm."

Since most (180 degrees) of the base circle is machine ground, therefore, there is a range of positions (approx 90 degrees) the lobe of the cam can be pointed to for accurate valve adjustment. Try pointing it vertical next time you adjust your valves, you will agree with me.

The words you quote say ' vertical relative to the rocker arm ' and the picture shows that as close to the one oclock position ... but you chose to use another position to set your valves...
The question is still why you think they would give those VERY specific directions in the FSM but you think they are just trying to roust your *** and make things difficult for you. And you even go to the extent of suggesting there is a 90 degree range which is acceptable.... Why would MB not just say ' point the lobe of the cam straight up ' if there were that kind of legitimate leeway ?

Even more important question is why you want to promote that 'alternate' contrary view to others...

vstech · #**171** 05-17-2015, 12:19 PM

Quote:

Originally Posted by Lucas

Yes, but if you only look at the marks on the balancer theres a 50% chance its at the bottom of the cylinder.

This is incorrect.

The only way the piston could be at the bottom of the hole with the timing mark at OT IS IF THE BALANCER IS BROKEN OR IN THE WRONG POSITION.

vstech · #**172** 05-17-2015, 01:12 PM

Quote:

Originally Posted by funola

The base circle is a machine ground surface, it would be difficult to make it not flat, therefore it is flat. As long as you are within +/- 30 degree of the center of the base circle, you will have accurate measurements.

Unless you have a damaged cam. The cam can be damaged from constantly riding with maladjusted valves... So, checking with the cam in various positions is a wise idea.

Lucas · #**173** 05-17-2015, 06:17 PM

Quote:

Originally Posted by vstech

This is incorrect.

The only way the piston could be at the bottom of the hole with the timing mark at OT IS IF THE BALANCER IS BROKEN OR IN THE WRONG POSITION.

You are correct sir. I totally got lost in all the madness. And im not the best at expressing my thoughts.

Lucas · #**174** 05-17-2015, 06:19 PM

Quote:

Originally Posted by vstech

Unless you have a damaged cam. The cam can be damaged from constantly riding with maladjusted valves... So, checking with the cam in various positions is a wise idea.

That's interesting.

Lucas · #**175** 05-17-2015, 06:22 PM

Quote:

Originally Posted by funola

The base circle is a machine ground surface, it would be difficult to make it not flat, therefore it is flat. As long as you are within +/- 30 degree of the center of the base circle, you will have accurate measurements.

So 30 degrees is flat? Where did this number come from? Just curious. Im going in there soon and can measure.

But us that just this motor (616)? Or is this for all cams.

I always have just pointed it directly away from the rockers. Ive never seen a disadvantage to this. Until Vstech's point.

funola · #**176** 05-17-2015, 07:24 PM

Quote:

Originally Posted by vstech

...., checking with the cam in various positions is a wise idea.

I always do that, and get the same friction "drag" with the same feeler gauge on the same valve.

funola · #**177** 05-17-2015, 07:26 PM

Quote:

Originally Posted by Lucas

So 30 degrees is flat? Where did this number come from? Just curious. Im going in there soon and can measure.

But us that just this motor (616)? Or is this for all cams.

I always have just pointed it directly away from the rockers. Ive never seen a disadvantage to this. Until Vstech's point.

+/- 30 degrees is 60. It's probably a little more. You can check it with a dial indicator if you really want to know.

leathermang · #**178** 05-17-2015, 07:44 PM

All this just to avoid using the simple and specific instructions in the Mercedes Factory Shop Manual...
Amazing.

Lucas · #**179** 05-17-2015, 11:22 PM

Quote:

Originally Posted by funola

+/- 30 degrees is 60. It's probably a little more. You can check it with a dial indicator if you really want to know.

I've just been kinda curious about cam design in general. Like beyond this concept. Lobe length vs hight, etc.

Wondering how similar they all are.

I would have to measure degrees turned too.

But I bet there's info out there I can find.

Stretch · #**180** 05-20-2015, 07:04 AM

After some real world advice from funola (who has proven time and time again that he has actually gotten out of his seat and done some real mechanic-ing and is most certainly not an "armchair mechanic") =>

Quote:

Originally Posted by funola

Just adjusted my valves. They got a little tighter since the last adjustment but not a lot. I couldn't find the remote starter that I made so had to make another one. I couldn't find a suitable momentary switch so took the case off of a spare Mercedes ice cube relay and soldered wires to it with alligator clips on the ends. Works just fine and will handle the current (7 to 8 amps). I would not advise using a relay as a momentary switch as you can accidentally trigger the starter if you are not careful. I hang it up in the air when not in my hand so it cannot be accidentally triggered. Here is a youtube of it. https://youtu.be/sIcoCBKpN7Y

It takes just seconds to position a valve. In this video, I point the lobe straight up, which produces the same feeler gauge reading as when the lobe is pointed at the oil feed tube. If pointed beyond the oil feed tube, the reading starts to increase. Because of that, I like to point it straight up, which is easier to see while standing in the front of the car.

I find this response particularly ignorant and obtuse =>

Quote:

Originally Posted by leathermang

Why don't you share with us your theory on why the Mercedes Factory Shop manual would show as the correct position of the cam lobe the one o''clock position if straight up is just as good ?????????
A bunch of Sadists just trying to rain on your parade... harass you from the grave.... a conspiracy aimed at planned obsolescence.....There has to be some grand theory which causes you to think the VERY specific instructions in the Factory Shop Manual are just suggestions from which you can find an ' easier ' way to do it.

Why are you here leathermang? It doesn't seem to be helpful...

A reasonable reaction from funola =>

Quote:

Originally Posted by funola

The FSM maintenance chapter for 1985 617 engine says: "measure valve clearance between sliding surface of rocker arm and cam base circle of camshaft by positioning camshaft so that tip of cam is vertical relative to rocker arm."

Since most (180 degrees) of the base circle is machine ground, therefore, there is a range of positions (approx 90 degrees) the lobe of the cam can be pointed to for accurate valve adjustment. Try pointing it vertical next time you adjust your valves, you will agree with me.

Produces yet more surly pedantic comments =>

Quote:

Originally Posted by leathermang

The words you quote say ' vertical relative to the rocker arm ' and the picture shows that as close to the one oclock position ... but you chose to use another position to set your valves...
The question is still why you think they would give those VERY specific directions in the FSM but you think they are just trying to roust your *** and make things difficult for you. And you even go to the extent of suggesting there is a 90 degree range which is acceptable.... Why would MB not just say ' point the lobe of the cam straight up ' if there were that kind of legitimate leeway ?

Even more important question is why you want to promote that 'alternate' contrary view to others...

Quote:

Originally Posted by leathermang

All this just to avoid using the simple and specific instructions in the Mercedes Factory Shop Manual...
Amazing.

I find that the problem with your insistence that everyone should read the FSM and follow its instructions is that this advice is variable with your feeling about winning an argument. If you can't win with the FSM tack you often change to "THE PHYSCIS INVOLVED". See for example =>

Quote:

Originally Posted by leathermang

Stretch,
I said the only way to ACCURATELY find TDC was from the physics involved in the design of the engine.. you said that was not true....I assume you still believe that... there I go again....

and for the record.... it can be found without any ' measuring devices'... no degree wheel and no dial indicator... only comparative indices ....

it can be found just with a way to place a marks on the crank end and a way to locate the same distance on the piston travel before and after TDC.... a physical comparison which can be as simple as a dowel. Then half way between those marks is TDC...

Where it can be necessary to find TDC accurately is when there is a problem with the original method the TDC is marked from the factory.... we discussed that some crank markings were on vibration dampers where the rubber had allowed the outside ring with the markings on them to move to a position not original to the engine.

This kind of comparative measuring ... where actual distances or weights are not found... is used to balance the weights of pistons, rods and things like that... you find the lightest and take off enough weight of the others so they match... using an easy to make balance beam comparator ... you never need to know the actual weight.. only the comparative mass of the items involved.

...the problem I see with this argument (again) is that I know of no engine manufacturer who has engraved timing marks on =>

Quote:

Originally Posted by leathermang

... some crank markings were on vibration dampers where the rubber had allowed the outside ring with the markings on them to move to a position not original to the engine...

<= now I'm not an expert on every engine that has ever been made. And for that reason the discussion we had (all those years ago) regarding an advanced method of finding TDC has been restricted (from my side) to the OM61X engines.

I make the point again - that if for some reason you want to find TDC on an OM61X engine (in an accurate way) you may as well use the method of checking camshaft timing in chapter 05-215 => Specifically that is resting a valve on a piston crown and measuring the rise and fall of the valve with a clock gauge / DTI. In my opinion this will provide more than enough accuracy for any home mechanic.