This mod opens up the front vent port on the solenoid and allows air from the front ram chamber to be vented faster.It does this by shortening the path that air has to travel to vent as well as greatly increasing vent size. The mod works on humphrey or parker solenoids, I just had a broken parker and one in my gun. Its a good idea to do this mod to an already ruined solenoid and if the drilling comes out good then just switch the block with the one in your solenoid.
Tools Needed: drill press, vise, drill bit (about .050"), oring pick.
STEP 1: Remove the solenoid from the gun. The solenoid pictured is a shego converted parker so it has no upper board but it disassembles the same. Then take the front and rear section off the solenoid so you just have the metal block. carefully remove the spool from the block. I like to scratch an arrow on the metal block pointing to the front cap. The block can go in backwards, I just prefer to put everything back together exactly like it was to ensure it seals correctly.
STEP 2: use a pin/marker to mark the solenoid block as shown in the picture. where the front most center hole's lines meets with the spools lines it creates a rectangle shown as the shadded region. Drill 3 holes evenly spaced completely inside the rectangle. Suggested size is .040-.055 to allow a small error buffer in the drilling and marking.
STEP 3: Clean the block with hot soapy water and a tooth brush or paper towel. Blow the block dry. Use the oring pick to knock down the burrs on the inside of the spool bore. The area where the new holes are drilled is already recessed so they don't have to be perfectly smooth on the inside, just dont have bits of metal sticking out too far.
STEP 4: Reassemble the solenoid as it came apart applying a light coat of lube to the spool before you put it back in. put the gun back together.
With my eigen setup my velocity went up 5-10fps and the consistancy was a bit tighter. It gave the gun a slightly more crisp sound. There were no settings changed in the test, just solenoid blocks swapped.
I'm going to updated the deburring of the holes with pictures here soon.