Hi all, Slowly going about the business of eliminating reasons for the "rough running" of my '66 300 (413) following its recent engine rebuild. Theory I'm testing currently is a vacume loss throught the power brake booster--a possibility first suggested by club members. As I've said, it would make sense, as I pulled the booster while the engine was out in order to paint the engine compartment. My question is...if I want to test the running of the engine without the booster in the system, can't I just close off the vacume line into the booster with my thumb? Wouldn't that effectively seal the system, and then if a vacume loss in the booster was the problem, the engine should begin to run properly? As always, thanks for the help, Jonathan __________________________________________________ Do You Yahoo!? Yahoo! GeoCities - quick and easy web site hosting, just $8.95/month. http://geocities.yahoo.com/ps/info1