The M156 / M159 cam phasing gear is bolted to the camshaft with no keyway, relying on just clamping force to hold parts in sync. Factory cam bolts are "torque to yield" and are very weak in material.
To solve this issue, Weistec offers M156 / M159 Camshaft Phaser Bolts. Manufactured by ARP to be twice as strong as the factory camshaft phaser bolts. With the Weistec M156 Camshaft Phaser Bolts, the phasers can be bolted to the camshafts with significantly increased clamping force ensuring that they will never spin out of proper installed position.
Whether you are installing Weistec CNC Ported Heads, assembling a completely built engine, or simply upgrading to M159 valve buckets, these bolts are a must.
