Haynes manual 42023, _Honda Civic '84 thru '91_, page 2A-10,
section 10, "Camshaft and rocker arms - removal" instructs

"3 Loosen the valve adjustment locknuts and back off the adjustment
screws until they no longer hold the valves open."

In this 1990 Civic Si, not entirely possible. At least two
exhaust and two intake valve springs are loaded in any position
of the camshaft. Is that usual?

Thanks, ... Peter E.