Hello Frans,
Check the basics first.
A lot of things can cause warm running and hot starting problems.
Your engine should be in tune. Check your compression, check the points, especially check your idle timing and timing at 3,000 rpms. A fresh set of NGK BP6ES spark plugs is an inexpensive but good investment since you will have the plugs out to check the compression.
You will need to make sure that the basics are in order first. Start with the Linkage Tour. Your engine linkages must be correct. Some of the dimensions will not be the same on your 220SE as our W113 cars but the section on the intake venturi switch is critical and a lot of the other information is relevant. The main fuel filter should be clean. Your fuel pressure should be up to specs. Low fuel pressure could be caused by fuel line restrictions, plugged fuel screens in the electric fuel pump or fuel tank and defective check valve on the fuel return line. Vapor locking fuel in the system can happen on hot engines if the fuel return line is restricted or the pump check is blocked. A lean running fuel mixture will also aggravate warm starting problems. A split linkage test on your warm engine will confirm this.
Good that you checked and understand your starting aids. Un-hook the metal fuel line going to the cold starting valve on the intake manifold. Remove the metal fitting screwed into the intake. Check to make sure that the fine screen in this fitting is not clogged. Also check the the slide valve moves freely. Re-assemble.
Get familiar with the "split linkage test" and see if your mixture is really going lean after all systems are checked.
Split linkage co test
http://www.sl113.org/forums/index.php?topic=11162.0Joe Alexander (ja17)
Blacklick, Ohio