First theres a tang for the secondary stop you can bend to adjust the amount the secondaries stay open. Its in the rebuild book. Theres also a set screw on top of the tree you can adjust.. I like to do that instead of cutting the spring. Thats just butcher work when you cut the spring. I understand there might be a vacuume issue but unless your idle vac is below 10Hg.. I wouldn't cut it. Theres a couple air bleeds under the tin covers one can also drill out. Bunch of things you can do to have a crisp, bog free Thermobog. As a last resort I'd drill the throttle plates, but the above usually gets everything running peachy. Oh.. and TQ's LOVE lots of initial timing.