hmm..I suspect it is easier to seal on a turbo. replacing the gaskets is pretty easy - but getting a good seal can be awkward on an atmo (in my limited experience)
The Atmo rocker covers are 'pressed' rather than 'cast' (as on the turbo) so you do need to be a bit careful - the covers can bend if you overtighten. Mine had slightly bowed flanges (no-one likes that) - and took a few attempts to seal properly. Avoid overtightening as it will deform the covers.
The LHS is a doddle..start with that one (if you do both)...the RHS is a little more tricky to access. (water pipes and heatshields get in the way) loosen heatshields - a bit messy, RHS requires some nimble fingers.
I remember removing the big rubber RHS coolant pipes - (a good excuse to drain/flush the gunge from the cooling system)...then put a bung/rag in any water pipes to stop any potential mishaps later (when the covers come off)
..then do the gasket work..then refit/refill cooling pipes (with mainy water - just in case you don't get a gasket seal - and need to repeat). Fire her up..Test the gasket. If ok. then drain/refill with correct coolant mix. (and hopefully you will have no oil (or new coolant
) leaks now.
(there have been posts on flushing/refilling the cooling on a GTA - have a search. If you want to flush the coolant/rust out..then the hints I remember.
- there is a bleed valve (rubber hose with a screw top) on the radiator which you can reach from the side.
-various techniques for flushing out the system involving garden hoses
-rad collects gunge in the bottom as the in/out pipes are halfway up - put a running garden hose into the rad to flush this out.