I installed all the new parts, checked and re-checked and double checked the timing marks. Pulled the pin, crossed my fingers and fired it up...... Nothing changed! The knock is still there just as before. Rev the motor and it stops briefly but will go back to the tapping/knocking. Any ideas?? It really doesn't sound like the engine. Do I remove the passenger head? Does anyone have a write-up on how to check the valve lash???