Nissan Repair: Engine Noise, head gaskets, noise question

Question
QUESTION: My P10 was changed Head-Gasket recently but the mechanic could not time the engine as before. I noticed timing chain noise when you start the engine which reduces in intensity but is still there as the engine runs. To add to this I have also noticed some noise coming from the top cover area may be originating from the shims. At the same time the vehicle can reach 80kph on the speedometer and jerks on gears 3,4 & 5. My vehicle is carburetted. What could be the problem?

ANSWER: Hi Lawrence -

What year and engine size is your car?

Aloha
calvin

---------- FOLLOW-UP ----------

QUESTION: Car is 1995 and engine is 1600 (1597 to be precise)

Answer
Hi Lawrence -

If the noise had started right after the repair, then I would take it back and have it checked. Perhaps the tensioner was not replaced or adjusted correctly, as it seems you have a sagging chain. When head gaskets are replaced, usually the head is shaven (resurfaced), which may cause additional play if the tensioner is not working properly.

Hope this helps -
aloha
calvin