Camshaft Shim Washers

[joebaehr]

My early 95 (flange plus drive gear style) had two shim washers each side when I disassembled. Reading Porsche tech manual it emphasizes getting gears parallel (not sure how shims would affect that unless they are referring to left and right gears) and that normally 4 shims are required... Anyone can help me figure out what to look at/measure to determine if I need more shims on re-assembly.

Thanks,

[DRACO A5OG]

Oh boy, if like the 3.2, you need a straight edge and with a caliper measure from the IMS to insure the cam ends are within spec then add or remove shims accordingly.

[ChrisBennet]

A 964 motor I built also had 2 shims on each side instead of the usual 3/4 (or is it 4/3?). I seem to remember hearing that others had found the same thing on other 964 motors
I have the correct tools for measuring parallelism but faced with the fact that the factory put the motor together that way, I put it back together the way the factory had it.

[DRACO A5OG]

Either way, you should verify the specs before you put it back together to avoid damaging components or worse the entire engine.

[Gordo2]

If you are re-using cams and cam drive sprockets - I recommend you stick with the # shims per cam as you found them when they were removed.

If you are changing / replacing cams, cam sprockets or other cam drivetrain that could change how the sprocket on the camshaft aligns with the sprocket on the crankshaft - I recommend you measure and add or remove shims as required. Searching "camshaft alignment" should provide info on how to do this.

The camshaft shims determine how far in or out the cam sprocket protrudes - which allows you to align it to the crankshaft cam chain sprocket. You want the cam sprocket and the crankshaft sprocket to be as close to parallel as possible - to ensure the camshaft drive chain doesn't bind on either sprocket causing undue chain and/or sprocket wear.

The spec tolerances are quite tight, however a number of home builders have found that although the tolerances are very tight - slight variations seem to be acceptable (i.e. 1 vs 2 shims on a cam makes very little difference for wear).

Good luck,

Gordo