Litt ny info om emnet The S52 and S50 cams are the same for lift (10.3/9.7mm) and duration (252/244).
The only difference is the cams are built from different cam cores, although they are both hollow cores. The S50 (M50 family) cams are built from "round" cores and the S52 (M52 family) cams have areas where there is additional material on the cam between the lobes and this material is squared off instead of round. I would assume that if the cores are the same material and core thickness, the S50's would be lighter in weight because they have less material in the areas between the lobes.
The reason M/S52 cams won't fit the cam trays for the M50 (only) is the square cores of the cams interfere with the tray. The S50 trays are unique to that motor, and M/S52 cams will fit an S50 tray ONLY. The S50 tray and M/S52 tray are the same P/N.
The whole reason I know all this is I've been swimming in cam details for the last few weeks. I was sold an S50 motor that actually contained M52 (2.8L) cams. The situation has recently been addressed and the appropriate cams (S50) are now making themselves at home in my motor.
Be careful out there when buying cams. Don't assume what cam you have by the casting number on it. You have to measure the lift to know for sure.
Just as an example, a 1718888 cam casting correlates to a S50 exhaust cam. It is precisely the same p/n stamped on the Group N 2.5 cam. These two cams have the same casting#, but different lifts and durations.
The Schrick 2.5L non vanos cam has 1738369 stamped on it, and so does the S50 intake cam.
You gotta measure the cams to know for sure.
Ed
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