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?

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[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!)


:neener: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?

62847

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 :

http://dmctalk.org/attachment.php?attachmentid=59128&d=1548807979

There's more detail here if necessary:

http://dmctalk.org/showthread.php?17149-Replacing-the-Frequency-Valve-and-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 :

http://dmctalk.org/attachment.php?attachmentid=59128&d=1548807979

There's more detail here if necessary:

http://dmctalk.org/showthread.php?17149-Replacing-the-Frequency-Valve-and-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.

[FABombjoy]

I'm guessing the hose fitting & that adapter adapter are flared, probably AN? I don't recall what the connection at the FV was offhand.

Typically these are torqued based on counting flats, like shown on this page. (https://image.slidesharecdn.com/hydraulic20fitting20torque20values-1331580085445-phpapp02-120312142724-phpapp02/95/torque-values-for-hydraulic-fittings-1-728.jpg?cb=1331562734). The vendor should provide specs based on whatever fittings they source.

You could use tubing of some sort as a kind of gasoline luge and drain it straight down. Or wrap it all up with a liquid sensor buzzer alarm.
I'd leave it as-is. Half the thrill of k-jet is driving around like you're hauling an old dusty duffel bag of sweaty dynamite.

[David T]

Typically you develop leaks after work has been done, a loose connection, a kinked or sharply bent line, a mis-positioned line, a missing copper sealing washer, that kind of thing. If you run the motor for a while and don't have any leaks, the chances of developing a leak are small. Even on the old, original lines if you treat them carefully and don't kink or abuse them while you are working on them. If you do replace the lines and don't use the proper tubing or fittings, then you do risk a line coming loose and a massive fuel spill. Carry a fire extinguisher. If you smell fuel, STOP and find the leak immediately. You should never smell fuel while the motor is running. Even a tiny leak must be fixed right away.

[DMC-81]

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.

You're welcome. Agreed on the U shape.


I'm guessing the hose fitting & that adapter adapter are flared, probably AN? I don't recall what the connection at the FV was offhand.

Typically these are torqued based on counting flats, like shown on this page. (https://image.slidesharecdn.com/hydraulic20fitting20torque20values-1331580085445-phpapp02-120312142724-phpapp02/95/torque-values-for-hydraulic-fittings-1-728.jpg?cb=1331562734). The vendor should provide specs based on whatever fittings they source.

You could use tubing of some sort as a kind of gasoline luge and drain it straight down. Or wrap it all up with a liquid sensor buzzer alarm.
I'd leave it as-is. Half the thrill of k-jet is driving around like you're hauling an old dusty duffel bag of sweaty dynamite.

In case anyone needs them, I included my research on the fitting type and torque specs for the FV in post 9 of the thread I linked to above, plus details of optional heat shrink wrapping of the bare braided stainless steel fuel lines in post 10.

[Michael]

Typically you develop leaks after work has been done, a loose connection, a kinked or sharply bent line, a mis-positioned line, a missing copper sealing washer, that kind of thing. If you run the motor for a while and don't have any leaks, the chances of developing a leak are small. Even on the old, original lines if you treat them carefully and don't kink or abuse them while you are working on them. If you do replace the lines and don't use the proper tubing or fittings, then you do risk a line coming loose and a massive fuel spill. Carry a fire extinguisher. If you smell fuel, STOP and find the leak immediately. You should never smell fuel while the motor is running. Even a tiny leak must be fixed right away.

You answer questions like I am an idiot. Not once did I mention that I had a leak or even suspected a leak but thank you for telling me to STOP when I smell raw gas while the engine is running. Thanks for telling me that a missed fuel seal will cause a leak or manhandling lines and stretching them would subject them to damage. I have carried a fire extinguisher in my car for years. Don't take this the wrong way, it seems like everytime you answer a question you are not trying to help but just make sure everyone knows how smart you are. I'm sure you are a great guy but please refrain from replying to my threads.

[Michael]

Luke and Dana, thanks for the links. I may redo my arrangement when I do my valve adjustment which I am working up the nerve to do myself.

[FABombjoy]

Are those from DeloreanGo? I'd shoot Arran a message and get a specified # of flats torque value. One piece looks like aluminum and will probably have a different value than the sample chart. I snapped an AN or two using the wrong fitting type values. I try to get steel fittings whenever I can but a few sizes seem to be only available in aluminum.

The good news is that once a flared fitting is seated they seem like they're sealed for life. I've had better luck with them compared to NPT or even O ring.

[Michael]

Are those from DeloreanGo? I'd shoot Arran a message and get a specified # of flats torque value. One piece looks like aluminum and will probably have a different value than the sample chart. I snapped an AN or two using the wrong fitting type values. I try to get steel fittings whenever I can but a few sizes seem to be only available in aluminum.

The good news is that once a flared fitting is seated they seem like they're sealed for life. I've had better luck with them compared to NPT or even O ring.
They are from DeloreanGo. I tightened the fitting down tight enough that I felt any tighter would risk stripping or damaging the mating surface. Heck I replaced that line way back around 2010 or 11 and I had no idea what I was doing then. Hasn't given me any problem.

The thing with these cars is the more you learn, the more you realize what can go wrong. It messes with your head. Sometimes ignorance is bliss.

[Delorean Industries]

The fitting between the inlet of the valve and AN line needs to be steel. Aluminum will not
Bed properly as you will crack the nut on the valve reaching the appropriate torque specifications. This is a disaster waiting to happen.

[Michael]

The fitting between the inlet of the valve and AN line needs to be steel. Aluminum will not
Bed properly as you will crack the nut on the valve reaching the appropriate torque specifications. This is a disaster waiting to happen.

I will ask about this very thing. Thanks

I have to admit the fitting felt like it was aluminium. I am referring to the piece anodized blue in the pic. Are you saying both parts need to be steel?

62872

[Delorean Industries]

The one that contacts the frequency valve needs to be. You can transition to a female an to male an.

[David T]

You answer questions like I am an idiot. Not once did I mention that I had a leak or even suspected a leak but thank you for telling me to STOP when I smell raw gas while the engine is running. Thanks for telling me that a missed fuel seal will cause a leak or manhandling lines and stretching them would subject them to damage. I have carried a fire extinguisher in my car for years. Don't take this the wrong way, it seems like everytime you answer a question you are not trying to help but just make sure everyone knows how smart you are. I'm sure you are a great guy but please refrain from replying to my threads.

When I post to a thread it is not only for the OP. It is for everyone who will read this thread and may not be as smart as you or have as much experience doing this stuff. If my replies offend you, don't read them. When you post, anyone can respond. If you don't like the rules you can either leave or stop posting.

[Michael]

When I post to a thread it is not only for the OP. It is for everyone who will read this thread and may not be as smart as you or have as much experience doing this stuff. If my replies offend you, don't read them. When you post, anyone can respond. If you don't like the rules you can either leave or stop posting.

Don't give yourself so much credit. Nothing you do offends me.

[powerline84]

Typically you develop leaks after work has been done, a loose connection, a kinked or sharply bent line, a mis-positioned line, a missing copper sealing washer, that kind of thing. If you run the motor for a while and don't have any leaks, the chances of developing a leak are small. Even on the old, original lines if you treat them carefully and don't kink or abuse them while you are working on them. If you do replace the lines and don't use the proper tubing or fittings, then you do risk a line coming loose and a massive fuel spill. Carry a fire extinguisher. If you smell fuel, STOP and find the leak immediately. You should never smell fuel while the motor is running. Even a tiny leak must be fixed right away.

What with the world do without the resident Delorean "expert"


I suppose my frequency valve cracking on its own after 3 years of driving had a david T explanation too....your exausting.

[Michael]

What with the world do without the resident Delorean "expert"


I suppose my frequency valve cracking on its own after 3 years of driving had a david T explanation too....your exausting.

Member: "I would like to find the square oil plug socket in a low profile to make my oil changes easier, anyone know of a source?"

Guru "Make absolutely sure you replace oil in the engine after you drain it! Use fresh oil, not the same oil you just drained. Also be sure to replace the oil filter when you change the oil!'

Judging by the brake booster thread and the thread from White Out, talking to people like they are 8 years old is a running theme with the guru.

[WHO1DMC]

You could take a old ratchet grind it down to make it fit.
This is another owners idea not mine.

Dave B.

[Michael]

You could take a old ratchet grind it down to make it fit.
This is another owners idea not mine.

Dave B.

That's what I did. Been using it for over 11 years. Guru just sat straight up in bed.
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[Michael]

Got some clear heat shrink in and slipped it over the valve feed fitting. I got a larger size for the brass but the 3/4 stuff barely fit over the AN fitting so when it shrank it got nice and tight. The rest may shrink more with more engine time but it's fine where it is. Once I find a bolt to fit the rear hole, I will move it back a few more inches which will not only get it out from being right over the manifold but relieve the stress on the feed line.

My thinking is if it's wrapped tight in heat shrink, if something happens be it a cracked fitting or leaking hard line, the tight heat shrink tubing which extends about 12" on up the line will prevent fuel at 70psi from shooting anywhere. It will still leak naturally but it will come out of one end of the sleeve (most likely the top since it's so tight around the fitting) well away from the manifold and hopefully I will have noticed a running issue before anything serious happens.

I don't know if it will work or not. It may just buy me a few extra seconds to get out if I am in an accident and the FV gets damaged. I'll take it.

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