What to consider when installing Schrick camshafts?

Schrick high performance camshafts are not series parts and must be installed with special care!

It is recommended to leave the installation of camshafts to a specialist.

You need to check the following before installing the camshaft to avoid damage to the engine:

  • Are the bearings in the cylinder head true to size; is the bearing surface undamaged? If the bearings are not in perfect condition, the installation of the Schrick camshaft is not recommended.
  • Does the Schrick camshaft rotate freely in the cylinder head or does it hit the cam casting (see Figure 6)?

    The camshaft may not collide with any component. It must be ensured that no moving parts collide with each other.
  • Is the lobe face of the cam follower sufficiently large?

    The lobe face length means on the one hand, the diameter of the tappet rod on which the point of contact travels along to the cam. With a lever, the lobe face length means the direction of rotation. The cam followers must be in excellent condition. (tappets, rocker arms, drag levers, etc.). For safety reasons, always replace the cam follower because faulty cam followers can cause irreparable damage to the engine.

During installation of the camshaft:

  • The resulting overlap lift (see Figure 2) must be measured on the intake and exhaust valve. Does it match the catalogue details?
  • How large is the drop height of the valve up to the piston (see Figure 3) when the piston is at TDC?

    The drop height must be a min. of 1.5 mm larger than the measured overlap lift (see Figure 2) of the camshaft. It must be ensured that at a max. overlap lift, the intake and exhaust valve retainer cannot touch each other (a min. of 1.5 mm distance).

    The upper valve spring retainer must have a min. of 1.5 mm distance to the scrape caps.
  • At which valve lift is the spring pushed all the way together (on block) (see Figure 4)?

    The valve spring must have a min. of 1.0 mm spring deflection reserve available at max. valve lift.

    When checking, it is not enough to spin the engine by hand. The distances must be measured.

Free movement of the camshaft

grafik_freigaengigkeit_nw.jpgenlarge

Schrick camshafts usually have a larger cam lift. This results in a larger rotational radius of the cam tip. It must be ensured that there is sufficient freedom of movement and that the camshaft does not collide with other components at any position.

Angular orientation of the Schrick camshaft to the crankshaft

The angular orientation can be adjusted in most cases with the series installation instructions.

However, all free movements must be ensured, in particular the free movement of the valves to the pistons, Valve freedom of movement and the free movement of the camshaft in the cylinder head (see Figures 3, 4, 6).

If manufacturer's installation instructions are no longer available, an example of how to basically set a camshaft is below:

  • Turn the crankshaft until the piston stops half stroke before top dead centre. Lubricate the camshaft and the cam follower with sufficient engine oil. Insert the cam followers and camshafts and tighten the bearing bridges evenly until all bearing bridges are in place; if the bearing brackets are tightened unevenly, the camshaft can break!
  • Finally, tighten the screws with a torque wrench/spanner.
  • Adjust and fix the camshaft to the correct overlap lift.
  • In motor rotation direction, the intake valve just opens and is already open to the overlap lift.
  • In motor rotation direction, the exhaust valve just closes and is already open to the overlap lift.
  • Turn the crankshaft until the piston on the valve in the overlap position is at the upper dead centre and secure it. Mount the camshaft drive, loosen the securing and tighten the drive.
  • Turn the crankshaft 720 degrees and re-measure the overlap lift of the intake and exhaust valve. If the values are unchanged, the camshaft is mounted at the correct angle to the crankshaft.

Valve springs, what do you need to keep in mind?

The valve spring must have a min. of 1.0 mm residual spring deflection available at max. valve lift.

The installation length of Schrick valve springs must match the information in the Schrick catalogue and must be set to the correct overall installation length. For example, by placing washers underneath or twisting off the lower valve spring retainer.

The springs must be well guided upward and downward radially to keep vibrations and wear low. This is the only way the spring has a long service life.

When using our camshaft kits with upper and lower spring plates, the correct spring installation length is achieved without reworking. For safety, the spring installation length must be re-measured.

The valve spring forces must therefore always be matched to the application. The force should neither be too high nor too low; both will lead to engine damage!


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