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6.9 cam timing marks

Started by ramiro, 29 September 2023, 08:08 AM

daantjie

Daniel
1977 450 SEL 6.9 - Astralsilber

ptashek

I've never seen a Mann filter look this bad inside. Wow.
1993 "Pearl Blue" W124 280TE
1988 "Arctic White" W124 200T
1979 "Icon Gold" W116 450SE

ramiro

Other question does anybody has a idea how i can get the dirt out of my fuel distributor without fully dissambling it ?

I changed the small filter in the inlet , run 3 cans of injector cleaner and 3 full tanks through the system also tried pushing compressed air backwards through the fuel distributor.

After all that i still have a dead miss that comes and goes at idle and very very low load like cruising at 50 kmh , as soon as the engine gets some load it runs smooth and sometimes stays like that at idle , i can also see the afr at idle going to 14.4 or even 15.5 when it's missing , when it's smooth the afr's are at 13.2 so i suspect that some cylinder sometimes doesn't get any fuel.

raueda1

Quote from: ramiro on 30 October 2023, 08:55 AMCrazy what a difference the cam timing makes , before the car refused to go faster then 220 on the speedometer now on a semi flat autobahn it goes to 240.
Also attached a picture of the broken filter , and it defintive was loose before i opened it, because i could hear it moving around inside when i was shacking the filter.

240!  Impressive!  I tried to do that once but my testosterone ran out at about 230kpm. :o

Anyway, how can you be sure that the FD has junk in it?  Big chunks of junk would presumably be caught by the screens in the WUR and final fitting filter on the FD.  Clogging would presumably limit fuel flow, and 240 takes a lot of fuel.  So, it seems unlikely to me that the car would go that fast unless everything was in pretty good shape.  Cheers,
-Dave
Now:  1976 6.9 Euro, 2015 GL550
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0

ramiro

Actually expected more than 240 on the speedometer, it is only ~ 225 according to the GPS , but hard to find anybody else that drives his 6.9 to the limit , another owner told me that his goes past 260 on the speedo but i don't really believe him because he also told he can push 2. gear to 180, one time i got it to 237 GPS but it was downhill and then it ran into the rev limiter.

But in the end it doesn't really matter it's just a good test to see if the engine perfoms like it should , for long drives above 180 the wind noises are to loud, my w126 500 se goes faster (230 GPS without problems) and is much quieter

I have no other explanation than the FD, ignition problems usually don't go away with load or high RPM , and also i can see the AFR getting lean as soon as the engine is missfiring.
Also did a test today and found that cylinder 2 is the culprit that also explains why i see it in AFR values because my wideband is in the passenger side.
I removed the injector line from cylinder 2, pushed the air plate shortly to the bottom with ignition on , and after that cylinder 2 is back again but most likely not for long.

ramiro

As expected took a drive again , engine run smooth for some time at idle an part load but then started misfiring again.
Pulled spark plug wires again and found that now it is cylinder 1 that behaves the same like cylinder 2 yesterday,  so most likely the dirt just moves around in the FD.

ramiro

Looks like i managed to get the dirt out , after looking at an other disasembled FD i found that the only real place where dirt could randomly affect different cylinders is the area around the piston , so i took the piston out cleaned it and blew through everything in the FD.
Now the warm idle and part load is smooth and so far stayed like that, only when cold it has a misfire like always but also runs at nearly 14 AFR when cold at ilde.
Also finally managed to mount my AFR gauge in the cluster, somehow it looks much brighter in the picture then in real.

 

raueda1

Quote from: ramiro on 08 November 2023, 12:59 PMLooks like i managed to get the dirt out , after looking at an other disasembled FD i found that the only real place where dirt could randomly affect different cylinders is the area around the piston , so i took the piston out cleaned it and blew through everything in the FD.
Now the warm idle and part load is smooth and so far stayed like that, only when cold it has a misfire like always but also runs at nearly 14 AFR when cold at ilde.
Also finally managed to mount my AFR gauge in the cluster, somehow it looks much brighter in the picture then in real.
Nice!  Also nice is the AFR gauge.  What unit is it?  Cheers,
-Dave
Now:  1976 6.9 Euro, 2015 GL550
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0

ramiro

It's not a kit that you can buy , i took this display https://www.ebay.com/itm/175477551543 , and an arduino nano + similar wideband controler https://www.14point7.com/products/spartan-3-lite-v2 .
Also3D printed a case for the display that fits in the cluster where usually the gear indicator goes , so there was no modification needed in the cluster.
If anybody is interested i can upload the arduino program and the 3d file for the case.

raueda1

Quote from: ramiro on 08 November 2023, 03:56 PMIt's not a kit that you can buy , i took this display https://www.ebay.com/itm/175477551543 , and an arduino nano + similar wideband controler https://www.14point7.com/products/spartan-3-lite-v2 .
Also3D printed a case for the display that fits in the cluster where usually the gear indicator goes , so there was no modification needed in the cluster.
If anybody is interested i can upload the arduino program and the 3d file for the case.
OMG, way over my head.  You're true engineer, not a hobbyist like me, but thanks!  Cheers,
-Dave
Now:  1976 6.9 Euro, 2015 GL550
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0

rumb

https://www.benzworld.org/threads/measuring-fuel-pressure-on-a-ke-jet-mercedes.3069332/

In this thread is mention of a device under development that would measure fuel pressure,the O2-Sensor, and vacuum.
The main module (just to attach to the diagnostic socket) can analyze system voltages, duty cycle, ignition timing and dwell angle.

Could be years before it materialized though....
'68 250S
'77 6.9 Euro
'91 300SE,
'98 SL500
'14 CLS550,
'16 AMG GTS

ramiro

Very interesting device , i actually planned to display other values but was not able to move controller away from the display because the signal doesn't like long wires, so i decided to just show afr.

Just in case anybody ever want's to build the same display i attached the program and the 3d file.

raueda1

Getting back to topic of valve timing, I've been reading up of the process for a while and plan to do it in the Spring. In the process I found some related info on another forum.  I thought I'd repost/crosspost here to kind of fortify the discussion here and concentrate info in the same place.  Hope that's OK, if not admins can delete (?).  Anyway, here it is:

Quote0/12/2010 6:23 PM
Hi,Yes very simple operation. Remove both cam covers, then while watching number 1 cylinder cam,rotate the engine until the lines ,as in Paul's picture line up with the notch in the washer. Check the other side(left ) is close ,then look at the crank shaft damper. the timing mark should close as possible to Zero -0- but often it will nearer to 5. if it is past 5 and nearer to 10 ,then the chain is worn and needs replacing.

A tip I learnt a while ago is to replace the chain then using the offset keys, Advance the cams 2 degrees to give more low end power .
To learn the basics of Cam 'degreeing' you need to know a few steps first.
How to check that the marks on the timing damper are correct (mercedes are almost always correct)
[ii] how to set up up the dial test indicator
[iii] understand what the cam is doing when the dial test indicator begins to open the valve and why that is so important to get an engine running as it was designed.
On our M-100 engines we check on the actual lobe.
This involves checking on the clearance ramps of the cam lobe. The clearance ramps are the slow lifting portions of the lobe which provide a smooth, transition between the base circle and the cam flank on both the opening and closing sides of the lobe.
On the clearance ramps, the first .010" or .015" of rocker arm movement is usually at the slow rate of .0005' per cam degree. In addition to gradually taking up the valve lash (necessary because of valve expansion and small deflections of the valve gear components), the clearance ramp provides the initial, gentle acceleration of the valve off its seat.

Only the end of the clearance ramp directly adjacent to the cam flank is actually used to open and seat the valve, while the remainder is used to take up the clearance and compensate for small deflections or runout in the valve gear. Since the clearance ramp rate of lift (velocity) is .0005" per cam degree, a slight error on your part of say .001" in checking the valve seat timing at a certain point on these clearance ramps, could account for 2 cam degrees (4 crank degrees) of error in determining the timing point . And it is very easy to accumulate .001" error if the dial indicator's stem is not running parallel to the lifter (cosine error) or if you view the dial indicator's calibrations from an angle (parallax error) or if the cam bearings are worn slightly.
This why it can pay to remove the rocker arms to remove influences on the cam movement.

Obviously then to properly determine the position of your camshaft in the engine, the cam timing must be checked at a Rocker arm height off the base circle where the velocity (rate of cam rise) is high enough so that small checking height errors of .001" or so will not result in gross timing damper reading error.


Many years ago a standard height was sought after by ISKENDERIAN racing cam engineers where all racing camshafts could be timed to give accurate results and in 1958 it was decided and later published in their top tuner's manual, "Valve Timing for Maximum Output" that .050" lifter rise off the base circle would be the accepted standard for their camshafts. This figure was ideal because it was Not far enough off the base circle to confuse the engine builder when timing the camshaft, and it was high enough to show effective valve timing (a point where the valve is far enough open to pass an effective air flow). Also, the velocity (rate of cam lift) of most camshafts is approximately .004" per cam degree at .050 ' lifter rise. Therefore, a .002" error in checking height would only affect the Crank Damper reading about 1 crank degree as shown in this picture. The ISKENDERIAN .050" lifter rise check was actually how Daimler engineers specified the correct method of checking cam timng ,who came first,the chicken or the egg ?


to begin your check of the camshafts, rotate the crankshaft until the No. 1 cylinder intake rocker arm is on the base circle (heel) of the cam lobe.
Position the dial indicator stem parallel to the lifter in both planes, and preload the indicator's stem .050" - .100" on the Lobe.
Rotate the crankshaft clockwise several times to determine the runout or eccentricity of the base circle. This should not exceed. 001 and should be centered equally on both sides of the zero on the dial indicator.
(you doing this to see if the lobe is worn and the cam is turning straight in the head)

Rotate the crankshaft clockwise until .050" dial indicator movement is detected and read the mark opposite the stationary pointer. It should read intake opening before T.D.C. (depends on which cam s your m100 has,the timing specs are different between the different market engines) .
Record your reading and continue rotating the crankshaft watching the lifter reach full lift and begin to descend and stop the crankshaft's movement at .050" dial indicator reading before zero.
The reading opposite the stationary pointer should be intake closing at after Bottom dead Center.
Record your reading and repeat your check of the opening and closing points of the intake cam to insure against human error in reading the indicator or crank damper .

If the cam is opening or closing at a different position compared with the factory specs and your chain is NEW, then you can fit keys which will move the position of the Cam wheel on the cam shaft to make the cam open and close Early or late.
As I pointed out before,you can alter the opening to make more power down low (normal driving) by advancing the cam (opening earlier) or more power at the top by retarding the cam (high speed driving) .

Comments welcome of course, and maybe it will help somebody else too.  Happy camming to all and Cheers,
-Dave
Now:  1976 6.9 Euro, 2015 GL550
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0

ramiro

If you want to verify if you cam shaft marks ar correct i would use the method in the workshop manual , you can also look in the online manual on this site : https://handbook.w116.org/cd/Engine/107/M117_45/05-215.pdf , it's for the m117 but the procedure is exatcly the same for the m100 except the timmings off course are different.