As part of my upgrades I want to use the metal tubing for my oil pressure gauge instead of the plastic tube. I put it into the back of the gauge with a new compression coupling and tightened the nut up. My question is should the line get tight enough that the line wont spin in the gauge. Now I dont have the gauge in the dash yet, but I can actually spin the gauge around on the metal line. I dont know if it will leak or not but that is why I wanted to use a metal line to keep the plastic from breaking at some point and ruining the new carpet. If I use a primer and a high speed drill to prime the oil pump and there is no leak do you think it wont leak when engine is actually running. My 74 carries 80 PSI of pressure at start up and about 60 PSI once warmed up. I am using the same style oil pump in this engine. Should I go back to the plastic tubing? Anyone else have any experience with the metal tubing?
Thanks
Rodney

Are you using copper, or aluminuminum line on it? The copper line is best, as the alum. line will crush a little more when tightening the fitting, so it may not get as good of a seal. Either way, it should be tight enough that it does NOT move on the gauge. Does the line have a flared end?

Joel, I am using the copper line. It does not have a flared end just the compression fitting that slides on the tube. Im just not confident about it sealing. As much as I hate to do it I may have to go with the plastic line. I bought the copper line from NAPA but it just doesnt seem to get tight. It feels as though if I make it any tighter it will snap off the back of the gauge. Now that would Pi_ _ me off! Maybe I'll start the engine with the gauge out of the car and see what happens. I was hoping to put it all back together but just dont have a good feeling about that connection.
Rodney

Rod, on a pressure line like that I wouldn't trust a compression fitting, it would have to be flared. Just my .02.

Sounds like a lack of, or incorrectly installed ferrule on the end of the line after the nut was placed onj the line. Ferrule pinches on line as nut is tightened and as that is happening nut tightens ferrule against fitting to make the seal and clamping force.

Yea...what they said!  If the ferrel is the wrong size, or the line is not pushed thru it far enough, you'll have that problem.

The ferel is the correct size but it doesnt seems to crip down tight on the copper line. Even after I take it off I can pull the ferrel back off the line and it should be squeezed or cripped on by then. I will try to get another ferrel or two and see if that makes a difference. Barry, the gauge doesnt have a flare end for a line so a flare is no good. The line goes into the gauge about 1/8 inch then the ferrel is suppose to seal after tightening down the cap. Just not happening yet.
Thanks guys for all your help. I'll let you know if a new ferrel works any better when I get a chance to get back on it next week.
Rodney

All else fails try a new fitting.