What has gone wrong ?

Had the head off, new valve seats (for unleaded) & guides. Had it resurfaced.

Put it back on. Make sure all bolts correct tension and right sequence for tightening.

Take it for a spin, great !!!

Have a look at rocker cover see last rocker on no 4 cyclinder has punched a wee hole (2mm round ) on the push rod side of the rocker cover. With engine running can see the rocker moving through the hole.

Damm !!

The engine is still running OK I presume?

Are you running a steel, or alloy cover? Some covers are a bit tight for clearence, especially if you have got a wilder cam in....

Engine running sweet as. Still has the original GT cam in, nothing wild ! Thats to come with the new engine I am building up,

Had the rocker cover off and checked valve clearence, well none where to spec so have adjusted them all.

Also put in new gasket (slightly fatter than the old one).

Looking through "hole" seems we have pleanty of clearence now. So just have to get the hole filled in. I was going to gas weld fill it.