Valve timing specification

[K-Jet]

Good evening,

I searched the forum and gathered my information and successfully checked my valve timing. I also learned some other things.

1. The W108 BBB has almost no information on the M130 motor, at least as far as heads and cams and such.

2. There are two sets of official valve timing specifications, that seem to be consistent but still should be known. The first I found on this post, which states that crankshaft rotation is measured at 0.4mm valve lift. https://www.sl113.org/forums/index.php?topic=15105.msg103470#msg103470

The second I found in my Tech Spec book for 1972 vehicles which states that crankshaft rotation is measured at 2.0 mm valve lift.



Both indicated my camshaft is about six degrees late, so they don't seem to be inconsistent. Even so, I thought I would share what I found.

Thanks,

K-Jet

[MikeSimon]

I had the same issue with the BBB trying to find information about the M130 heads. Not until Joe Alexander pointed out that most of that is in the previous edition BBB, going back to 1959. You have to go there, if you rely on the BBB

[K-Jet]

Thanks Mike. Do you know the name of the book, or how I could identify it?

Also, if anyone has one that they are willing to part with, I would put it to good use.

[DavidAPease]

K-Jet,

I think this is the manual you need:

https://www.ebay.com/itm/163663806733

        -David

[K-Jet]

Got it! Thank you.

Any thoughts on the change from 0.4 to 2.0mm valve lift in the specification? I am checking both...

[cfm65@me.com]

Hi Guys,
I have the BBB mentioned above, but I can’t find the required clearances for the 250SL, 129 engine. Not in the BBB or in the pages posted by K- Jet above.

Regards
Chris

[K-Jet]

So some data from installing various offset Woodruff keys, looking for consistency between the 0.4mm lift specification and the 2.0mm lift specification.
- Measurements were done with a dial gauge and digital degree wheel.
- Results are the average of two measurements, which were always very close.

The specification for 0.4mm lift is 11 degrees BTDC
The specification for 2.0mm lift is 15 degrees ATDC

                                          Crankshaft position
Part number   Cam advance   @ 0.4 lift  @ 2.0 lift
621 991 04 67  2 degrees          6 B         11 A
621 991 02 67  3 degrees          8 B         14 A
621 991 04 67  5 degrees        11 B         11 A (which can't be right)

By the 0.4mm specification, the 5 degree offset is best. By the 2.0mm specification, the 3 degree offset is best. Crap.