Hello,
My info shows the "70" having a *duration of 112, but I do not see that it was ever used on a 230SL?
*By "duration" we are referring to the total no. of degrees an intake and an exhaust valve are open on one cylinder, during a single revolution of the camshaft. This duration is directly related to the ability of different cam shafts to produce horse power in some cases.
"Cam Swapping" a bit more complex than what meets the eye..............................................
Depending on the year and version, things to be cautious about when swapping camshafts with earlier or later versions;
-There are hollow internally lubricated camshafts (earliest) and the later solid externally lubricated camshafts with the external oil tube.
-There are skinnier lobe camshafts (early) and wide lobe camshafts (late) the rocker arms have skinny or wide contact surfaces to match their respective cam shafts.
-The early skinny lobe cam shafts also had cylinder heads with smaller diameter pressure pads on the valve spring cap, under the rocker arm. In addition the "valve spring cap" for these smaller diameter pressure pads was also different from the later spring cap.
-improved steel alloys and/or improved hardening processes are used in some version cam shafts and rocker arms.
-cam stands (cam bearings) may have different diameters depending on the version. Later versions had the larger diameter cam stands.
-when swapping cam and cam bearings, always check the height of the "foot" (the part where the head bolt goes) of the cam stand to the originals. This height may vary and may require a set of different length head bolts.
-original Mercedes cam shaft lobes and rocker arm contact surface, on these cars are case hardened (nitrited). Re-ground cam shafts will not last unless they are also case hardened.
Joe Alexander (ja17)
Blacklick, Ohio
