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Old 02-14-2009, 08:59 AM
Mike D Mike D is offline
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Join Date: Jan 2006
Location: Tucson, AZ
Posts: 5,358
The ball on the end of the line and the socket of the injector are of different hardness steel. They are an "interference" fit.

You are attempting to create a seal between the mating surfaces by compression. Cranking down on the line nuts can cause scratches on the sealing surfaces which result in leaks, which results in cranking down the nuts tighter, which leads to.....

Eventually you stretch or warp the softer metal nuts and they don't provide the proper tightening torque.

Examine some old injector lines. You'll see a "cup" shape worn into them. This is from either the lines being too loose and allowing the ball to rattle in the socket or from being crushed into the much harder injector receiving socket.

Last edited by Mike D; 02-14-2009 at 09:22 AM.
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