Engine noise

[HandyAndy]

Today I have finished my exhaust down pipe & connected the silencer & fabricated a bracket to hold the silencer in place to the chassis,

So, I started her up, nice & quiet

Now thats its able to run with the full exhaust system in place I decided to let it get up to temp, which it did nicely........

BUT

Once it had warmed up I can now hear what I can only describe sounds like a "Tappet noise", even tho the CVH engine i,m using has Hydraulic valves etc,

So,,,,,,,,,whats this noise? any hints please?

I did the screwdriver trick to the ear from on top of the rocker cover & it sounds like its coming from number 3 cylinder ( from rad to cockpit counting) valve setup

any idea,s ?

By the way, the donor it came out of has a full service history with 92k genuine on the clock.
cheers
andy