steel fuel line buzz Options

[eyesright]

A coupe of years ago I replaced the original fuel lines with steel brake lines. It is a '72 with original FI and fuel pump relocated to the front by PO. I used a right angle fitting at the firewall rather than bend the line. On driving, the fuel lines buzz with a harmonic at all speeds that isn't nearly as prominent when not moving. I have covered the exposed lines with old rubber lines and secured them pretty well but no effect on a still noticeable buzz.

I am replacing the fuel lines now in a '76 and have steel lines long enough to bend.

If the harmonic buzz in the '72 is from cavitation at the right angle joint when there is significant fuel flow, then this should not occur with the '76. (I recognize that there is fuel circulation even at idle, but I don't get near as much harmonic buzz at idle. And it'a a much higher buzz than I would expect from road vibration.)

In the future I'll really tie those suckers down in the engine bay and where ever I can reach in the tunnel in the '72 to see if that helps or replace them with longer ones like the '76 if that is successful.

Has anyone had this problem or any ideas to offer?

[76-914]

Harmonics (overlapping nodes on the harmonic scale) are vibration induced and destructive. That being said, I doubt very seriously that is what you are experiencing. I think one of the old metal clips is in contact with the line. Remove the 3 bolts holding the shifter in place then rotate the base of the shifter 90 degrees to expose the tunnel and the lines. Push the lines towards the pass side a few inches and see if it goes away. I don't believe that the fuel passes thru the line fast enough to cause turbidity or cavitation problems, either.