It says in the Holden Shop Manual to adjust the valve clearances with the engine running and when at normal operating temperature.
Having the engine running just seems to make a mess with the oil and squashes the feeler guages.  I tend to do it with the engine stopped and turned over by hand to where the valve being adjusted is fully closed.

My question is :  
Does anyone adjust their valve clearances with the engine running and does it pulverise their feeler guages??

thanks lindsay 58 and fcV8.  I will try a HQ radiator for size.  The standard one definately isn't big enough in brisbane heat.

thanks stinky,

I will be interested to see how it fits.  It is the height that appears to be the problem.

What other bigger holden radiators will fit into an FC that is running a red motor?  I don't mind doing a bit of cutting to make it fit, but what type should I get?

To change to auto you will have to enlarge the tunnel, mate up an auto gearbox ( trimatic probably ) to the grey, run transmission lines to the radiator, change your steering column or put in a floor shift, change you pedal assembly and it will be very difficult to find a compressor setup that will bolt onto the grey.  An auto with a/c on a grey will leave it quite breathless, so it may be better to just go to a HR front end and then you will be able to run a red motor which can handle it no problems.  Good luck.