Stovebolt engines that sit idle for a long time are really bad about getting sticky valves. That's particularly true if gasoline is added to a fuel tank that has been sitting empty for years. Gum, varnish, and other byproducts of fuel that has evaporated are suddenly dissolved and ends up causing valves to stick in their guides. Be sure you're using fresh gas from a clean temporary tank for the initial startup and run-in, and clean or replace the vehicle's fuel tank before trying to use it. Soaking the valve guides from the top with a penetrating oil such as KROIL, PB Blaster, spray carburetor cleaner, or whatever similar product might be available to you is a good idea, but the only sure fix for sticky valves is a cylinder head rebuild- - - -that consists of regrinding the valves and seats, and cleaning out any sticky deposits in the valve guides.
Jerry
