Engine knock, cam tooth off?

[[email protected]]

Hey guys,

My timing belt service was going really great untill i turned the car on and heard a knock.. couldnt even see the timing marks on the crank pulley with a timing light. 

When aligning  the cam gears and crank with the timing belt, they were almost perfect. However could the above symptoms be an effect of crank or a cam gear being off by one tooth?

Cheers

[Robocop2310]

When does this knocking occur?

Pre-ignition or after? After changing the timing belt did you also replace the tensioner too? 

Does the knocking sound like a constantly tapping or pinging sound? Could also be caused by valve adjustment problems, the belt being installed incorrectly or is defective.