upgrading fuel lines on N14

As long as the lines are properly secured you should have no worries about chaffing or rubbing. I am not aware of any consequence of using other type of materials for fuel lines as long as the material is fuel compatible and rated for up to 300 psi.

 

First of all, I think you need to find another mechanic...
Secondly did he tell you what was causing the excessive vibrations ?

Stay with the solid copper lines, you don't want any kind of rubber on the high pressure side of anything.
No engine maker has anything other then solid lines on the pressurized side.

The only 2 things I can think of that could cause that kind of vibration issue is needing a overhead or a bad dampener (harmonic balancer)
Now a clogged fuel filter or getting air into the fuel lines from the suction side will also cause the engine to run/idle rough too.


Too many parts changers out there... find yourself a real mechanic and fix the cause of the problem. Then again he might think he found a sucker that will fall for anything and can milk you out of your money.

 

There is also an oring on the fuel pump. It is a common wear item and you can replace filter as well as oring. Mine was leaking from here. It is right next to the crossbraided onnection