New knocking noise

[brian GT6.]

So my gt6 engine has finished running in and one of my winter jobs was to re-torque the head.

 

I did this and then re-set the valve clearances. On start up I heard a slight tapping/knocking sound. It hadn't been doing this before so I thought maybe I did a valve clearance incorrectly, or maybe missed one. 

 

So, off with the rocker cover again and re-doing the clearances. Maybe one was a tiny bit out - say 12 thou instead of 10 but nothing much. I started the engine with the rocker cover off and no noise. So I thought must have been the clearance. Put the cover back on and I can hear the tap/knock again. Took it to the shops to get essentials and gave it full throttle in second when warm and it sounded silky smooth from within the car. Yet in the garage I can hear this slight knock at tickover.

 

Any thoughts?

[Steve P]

Standard rockers and cover?,

My roller rockers fouled the cover slightly so had to adjust the cork gasket?.

Steve

[Nigel Clark]

Just now, Steve P said:

Standard rockers and cover?,

My roller rockers fouled the cover slightly so had to adjust the cork gasket?.

Steve

Ha! Steve just beat me, I was about to ask what rocker cover you have.

Nigel

[Pete Lewis]

does sound rocker cover related,  is it tin or alloy ?

old trick if you wish to double check rocker noise  use an old feeler poke it in when idling , does it change any  tapping , if so then its a worn rocker pad 

[brian GT6.]

It's a tin cover but I might have tightened it down more than it was before. Will try the feeler guage

[dave.vitesse]

Are there any marks inside the cover due to contact with the rockers.

Dave

[Nigel Clark]

39 minutes ago, dave.vitesse said:

Are there any marks inside the cover due to contact with the rockers.

Dave

And does the knocking disappear if you run the engine briefly with the rocker cover removed?

Nigel

[Pete Lewis]

if you have over tightend you can easy dress the distortion back with a  wood block and mallet 

think you already said the noise goes if the cover is off   ....so thats the look see you need to examine 

do have a carefull look at any odd pushrod action . is one bent ?   check all valve springs are intact there isnt a coil failed on one 

Pete

[brian GT6.]

Ok, so knocking noise solved.  

 

Started her up and getting regular noise again , tiny bit worried it was a small end. 

 

Rocker cover off , no noise and tappets sound perfectly adjusted since I double checked them. Rocker cover back on with engine running , no noise.

 

Tighten bolts slightly and no noise.

 

Tighten middle bolt up to torque and noise starts. Can slightly feel a tap. So undo but half a turn and noise goes away.

 

So it was the Rocker cover slightly contacting a tappet. Not hard enough to mark it though . Sorted!

 

 

 

 

[Pete Lewis]

i see an nice alloy one on a christmas  or virus escape   wish list   

Pete