Is it absolutely necessary to drop the engine in order to remove the head?
Probably not, says he never having done it :augie. The engine is however a stressed member of the chassis and the major connections to the frame are on the front side of the head. So, it might be tricky getting the head out of position to remove it.
I believed it necessary to remove the head to reinstall an exhaust valve resting on a piston. I got around it.
I removed the exhaust header, and with forceps, guided the valve back into the valve guide. I then used the piston to raise the valve to where I could get a magnet on it.
I then lowered the piston, fed nylon cord down through the spark plug hole until I couldn't jam any more in there, leaving a tail hanging. I then raised the piston to compress the nylon cord and provide resistance to the valve from below.
A circus of c-clamps enabled me to compress the valve spring, using a cut up piece of electrical conduit, far enough to reinstall the valve spring keepers.
Nice one..
I did the Nylon Rope thing on my HD years ago, felt very weird to do, but worked a treat..
I love thinking outside the box!
For future knowledge, it's not necessary to drop the engine to remove the head. BUT. you needto lock the crank first so that nothing moves while you do it. If you disturb the liners at all, then you're into removing them and reseating them using Blue Hylomar, otherwise you'll get a coolant leak into the crankcase.
And after you have the head on the bench with the cams off, don't turn it upside down. You'll end up with a pile of shims and a world of pain working out which goes where. Don't ask me how I know... :icon_rolleyes:
The solution was I did a guess build, measured the clearances then sent those plus the shim thicknesses and tolerances to my clever daughter who put it all into a spreadsheet and gave me the details for rearranging them. Result!