My guess is that even though you checked the ring end gap, it still wasn't enough. Remember you're running a blower, and that's a little extra heat. Either that, or mebbe you were given the wrong rings, or even a bad set. Sorry about your luck, dude.
If I remember correctly, the second rings are perfectly square. My concern is if they were put on upside-down??? Maybe yours are shaped and supposed to go in a certain way??? Hope you find the problem, it sounds pretty severe.
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Capri306, Moderator, The Mustang Works Online
1979 Mercury Capri, 5.0L -- C4 -- 2.73
1987 Mustang LX Notch 
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