Nissan Repair: Engine knock

Question
Just had new timing belt, heads shaved and gaskets replaced, new manifolds  and gaskets replaced, and upon start up I get quite an engine knock which goes mostly away after a few seconds(30), Although my hearing is not as good as it used to be I can hear it going down the road, not as loud but still there. My mechanic says no way to adjust a hydraulic lifter, which is what it sounds like to me! 1990 Nissan D-21 3.0 V-6 Hardbody SE

Answer
Hi Steve -

Have your mechanic check the alignment of the timing belt. If the belt is one notch off in advance, the knock will occur.

Engine knock is caused by premature firing of the cylinder which knocks the cylinder piston to the wall of the block, which is the sound you hear. Normally premature firing is caused by improper engine timing (timing belt), or subgrade fuel (not enough octane).

Hope this helps -
aloha
Calvin