I was perusing one of my favorite sites, Ken-ichi Tsuzuki, where his current project is a Harley. http://modelicengine.la.coocan.jp/harley191102.html What caught my eye (near the bottom of his connecting rod build) is where he is mentions 'fast reaction between aluminum & copper alloy'. I noticed the same thing installing bronze valve cages into my 6061 head. On one of my testers I was twirling the cage slightly to get a nice annular coating & then, surprise, it started bonding & I barely had time to push it down bottomed in the recess hole. Caught me off guard. Usually one can play with it for a while. It was 648 & the specs say 3 minute fixture time. Anyone else had this experience or know of information that pertains to certain alloy combinations kicking the set up time like this?