As has been said before, it it won't pop with ether, you've got other problems. I'd check the valve timing first to make sure the cam hasn't jumped time due to worn or broken timing gears. If the valve timing is on, check to make sure the compression release isn't holding the valves open.

Just to clarify, if you "rock " #4 Cyl valves (firing order 1-3-4-2 ) then BOTH #1&#4 cyl's will be at TDC + or - a few degrees ! BUT #4 cYL WILL BE BEGINNING THE INTAKE STROKE while #1 cyl WILL BE BEGINNING THE POWER STROKE ! The Valves on #1 will be CLOSED ! Then you will know #1 is supposed to be FIRING ! Then you will be SURE you are NOT 360 degrees out ! Using a prybar BACK the flywheel @ 60 degrees BTDC ( Clockwise - viewed facing the flywheel ) then turn the flywheel COUNTER-CLOCKWISE until you reach the fuel timing mark on the flywheel as SJ says or use the Dial- Indicator method (The Most Accurate Method ) as OLD-MAGNET suggests ! Glen