Making the frequency valve safer

[Michael]

So after installing new lines on my car, I couldn't help but be a little concerned by my feed line to the FV. I actually had this very line leak on me several years ago and replaced it with a NOS (incidentally the car is a refurb and the line that leaked was also NOS).

Fast forward to last week. The new stainless braided line does protrude a bit more over the headers which got me thinking a leak at that fitting would be very bad. I wondered if I were to order some 1/2" clear heat shrink, remove the line from the distributer, and slide the tubing over the fitting and flange, that might be the difference between disaster and getting off the road and stopped before any serious damage. Am I being paranoid?

20200306_160229.jpg

[FABombjoy]

Did that kit come with a little rubber hose for the return side? That's the part you should be more concerned about. Hose barbs on K-jet are intended for solid fuel hose (nylon, PTFE), not rubber EFI hose. But at least that side is low pressure.

Those flared fittings are very reliable and should be good for life once torqued. At 70psi, putting heat shrink over a leak might just be like holding your thumb over a hose.

What was the source of the leak on the OEM hose?

[Bitsyncmaster]

I split vacuum hose to cover tubing from sharp corners. That would probably insulate the heat also a little.

[powerline84]

When my frequency valve failed it split the plastic. I got lucky

[81dmc]

3 options to make a kjet equipped car safer:

1.)Convert it to EFI
2.)Convert it to carb
3.)Engine delete (I did this and my car has been trouble free for a year!)


You're paranoid.

[DMC-81]

So after installing new lines on my car, I couldn't help but be a little concerned by my feed line to the FV. I actually had this very line leak on me several years ago and replaced it with a NOS (incidentally the car is a refurb and the line that leaked was also NOS).

Fast forward to last week. The new stainless braided line does protrude a bit more over the headers which got me thinking a leak at that fitting would be very bad. I wondered if I were to order some 1/2" clear heat shrink, remove the line from the distributer, and slide the tubing over the fitting and flange, that might be the difference between disaster and getting off the road and stopped before any serious damage. Am I being paranoid?

20200306_160229.jpg

I think you'd be fine. I don't know what clearance you have with your air cleaner, but you could optionally orient the line like below to get it further away from the headers :



There's more detail here if necessary:

http://dmctalk.org/showthread.php?17...d-Return-hoses

[Michael]

Did that kit come with a little rubber hose for the return side? That's the part you should be more concerned about. Hose barbs on K-jet are intended for solid fuel hose (nylon, PTFE), not rubber EFI hose. But at least that side is low pressure.

Those flared fittings are very reliable and should be good for life once torqued. At 70psi, putting heat shrink over a leak might just be like holding your thumb over a hose.

What was the source of the leak on the OEM hose?

Return hose I'm not worried about as the pressure is not a concern. The feed hose I theorized if it did leak under pressure, instead of a high pressure stream it would collect in the tubing and hopefully drain, at least long enough for me to hear a running problem and stop the car.

I tried to convey in my original post that I didn't think it would stop a leak, merely offer a chance of preventing disaster if it leaked.

I didn't torque it since the only torque wrench I have is a socket. One thing I couldn't understand is why replace the return hose at all? If they are going to give you a rubber hose to connect the nice braided line, it just makes no sense to do it. If I had it to do over again, I probably would have left the return hose stock.

[Michael]

I think you'd be fine. I don't know what clearance you have with your air cleaner, but you could optionally orient the line like below to get it further away from the headers :



There's more detail here if necessary:

http://dmctalk.org/showthread.php?17...d-Return-hoses

Thanks Dana. Yeah I played around with it to try and keep the line from bending too much. A "U" shaped hard line would have been better. The air cleaner clears but I may reposition it like yours and see if I like the fit better.

[CFI]

I recently replaced my fuel lines as well. I ended up moving the frequency valve as far back as I could. I don’t know what kind of difference it will make fire wise, but there seems to be less stress on the return line in this position.

[Michael]

I realize that wrapping will not stop a full on break or failure, but the one time my line leaked it was a tiny crack causing a needle diameter fuel stream shooting across the compartment (fortunately my hood was open and I was working on it at the time). All I'm saying is it seems a piece of tubing might prevent or at least give the driver a few extra seconds to ascertain there is a problem before a fire breaks out.