Sometimes you can free up the valves through the spark plug hole. But don't get too violent. Tap the valve that you can see with a screw driver, if you can't see the valve it's not far. I've used a bent screw driver and felt for the valve. First take out the plugs and turn over the motor and see witch ones aren't moving and go from there. You may have to repeat this a few times. If you have compression in that many cylinders it may start like that and that will warm it up and loosen the others. If it starts there is no need to rev it up too much as that won't give the stuck valves time to operate. Good luck. That good damp Ontario air is great for sticking valves in the old flatheads. Mine used to sit sometimes for a few years and they were always sticking. Since I brought it out west I haven't had any trouble at all.
