Hello,
Make sure about the ID nuber on the back end of the camshaft. I have seen these stamped numbers very difficult to read correctly.
The Number 180 051 8601 is a fairly "hot" cam. It was used in the 250SL prior to any emission influences in the US or abroad. These cams were also used in the 250SE sedan engines of the era and some other MB models. These cams were stamped with "86" on the back end.
The "04" camshaft had ten degrees less duration and this happens mostly because the valves close earlier on the tamer "04" camshaft. I suspect that this was an emission decision.
Here are the specs of your two ( #86 and #04) ..........
Intake valve opens on the 86 at 11* and on the "04" at 11*.
Intake closes on the "86 at 53* and the "04" at 47*
exhaust opens on the "86" at 47* and the "04" at 48*
exhaust closes on the "86" at 21* and the "04" at 16*
If you do the math you will see that the "04" cam has about 10 degrees less total time the valves are open (duration).
Mercedes staight six cylinder engine cams of the era
Earliest camshafts of the era were hollow with holes. The valve train was lubricated by the engine pumping oil through the camshaft and squirting out the holes in the camshaft.
Next major change, the camshafts became solid. An oiler tube was added to squirt oil on the cam lobes, cam bearings and rocker arms.
Next major change, the rubbing surface on the camshaft lobes and rocker arms became wider.
Last major change, the camshaft main journals became larger diameter.
Minor changes along the way were mainly improvements in the steel and hardening processes.
So be aware of some of the changes when you decide to try a different camshaft.
Hottest cams of the era were #02,#09 #76, and #84 (142 degrees total duration valves open) most of these were early or late W113 camshafts.
Next were #11, #46, #86, (132 degrees total duration valves open)_
Then #01, #05 (130 degrees total duratrion valves open)
Then #04, #08, #14-1, #60, #60, #61, #11, ( 122 degrees total duration valves open)
Lastly #14, #33, #39, #42, #61, #70, #79, #82 (116 degrees or less total duration valve open)
I cannot verify that the "04" camshaft came from the factory in any W113 engines. With the "04" cam, the engine would run decent but may be a bit down on power.