Fuel line coupling size

[jonbarrett]

Any idea what the dimensions of the compression coupling is where the flexible fuel hose joins the steel fuel pipe under the wiper motor.

Also, what are the metal lines made of. They are magnetic so I assume they are mild steel. Mine are showing some surface rust. If they are liable to corrosion should they be checked from time to time.

[Erich Stahler]

jonbarrett said:

Any idea what the dimensions of the compression coupling is where the flexible fuel hose joins the steel fuel pipe under the wiper motor.

Also, what are the metal lines made of. They are magnetic so I assume they are mild steel. Mine are showing some surface rust. If they are liable to corrosion should they be checked from time to time.

Ah Jonbarrett, sorry to jump on your thread, but a very timeley posting, where do your steel lines run, along transmission tunnel inside the cabin or along the sill? any pictures would be fantastic, I want to replace my rubber lines that run inside the transmission tunnel for the later setup like you have.

[jonbarrett]

I have no pictures but from what I recall, they run from the tank, under the centre arm rest, up behind the centre cubby hole, over the passengers knees, and exit through the bulkhead under the wiper motor.

It's a rather strange place to place the metal/rubber coupling because if it fails it sprays fuel straight onto the exhaust manifold!

I'm manufacturing some new bulkhead brackets to lift the rubber hoses well away from the manifold.

I've got to reroute some cabling this afternoon and might be able to get a couple of pics in the passenger knee area.

[Erich Stahler]

jonbarrett said:

I have no pictures but from what I recall, they run from the tank, under the centre arm rest, up behind the centre cubby hole, over the passengers knees, and exit through the bulkhead under the wiper motor.

It's a rather strange place to place the metal/rubber coupling because if it fails it sprays fuel straight onto the exhaust manifold!

I'm manufacturing some new bulkhead brackets to lift the rubber hoses well away from the manifold.

I've got to reroute some cabling this afternoon and might be able to get a couple of pics in the passenger knee area.

That would be great, good luck with it anyway.

I thought the lines were stainless also, though knowing TVR anything is possible I suppose. Someone suggested the solid lines could be remade in copper tube, I suppose it would be fine from a pressure point of view just being softer than stainless could be easily flattened.

[jonbarrett]

Eric

Didn't get a chance to take any shots today. I've used a magnet to test the lines and they are strongly magnetic, suggesting mild steel. Not sure what the surface coating is.

Not sure if they run standard fuel lines but if you ever get a chance to visit any of the race Cerberas at Brands they are fully stripped and would show the routing and fixings.

[Erich Stahler]

jonbarrett said:

Eric

Didn't get a chance to take any shots today. I've used a magnet to test the lines and they are strongly magnetic, suggesting mild steel. Not sure what the surface coating is.

Not sure if they run standard fuel lines but if you ever get a chance to visit any of the race Cerberas at Brands they are fully stripped and would show the routing and fixings.

Not to worry, annoyingly I was at Brands when Itsayellow's was testing his cerb, I had a good look at the stripped inside of his car but at the time did not give the fuel lines a thought, typical!

[Nefarious]

Erich Stahler said:

Someone suggested the solid lines could be remade in copper tube, I suppose it would be fine from a pressure point of view just being softer than stainless could be easily flattened.

Copper is a no-no for fuel lines. I can't remember the exact reason - might be durability/pressure, might me some sort of chemical reaction, but I do know that it's regarded as not a good idea.

[Erich Stahler]

Nefarious said:

Erich Stahler said:

Someone suggested the solid lines could be remade in copper tube, I suppose it would be fine from a pressure point of view just being softer than stainless could be easily flattened.

Copper is a no-no for fuel lines. I can't remember the exact reason - might be durability/pressure, might me some sort of chemical reaction, but I do know that it's regarded as not a good idea.

I would tend to shy away from copper myself, however I remember my PI Triumph TR6 used to have solid copper lines under the car linked to braided flexible and that ran 100 psi fuel pump pressure?

[jonbarrett]

Here is what the lines look like exiting the bulkhead.

[GreenV8S]

Nefarious said:

Copper is a no-no for fuel lines. I can't remember the exact reason - might be durability/pressure, might me some sort of chemical reaction, but I do know that it's regarded as not a good idea.

Do you have any more information on that? I've had it suggested in the past that there may be an electrolytic issue with copper pipe / steel pump, but never managed to find any tangible details.

[Erich Stahler]

jonbarrett said:

Here is what the lines look like exiting the bulkhead.

Ah ha, that makes it a lot clearer, those solid pipes look fine, just slightly discoloured with age, don't suppose you would mind measuring the diameter of the tubing and wall thickness?

[jonbarrett]

Strangely enough I measured the diameter yesterday but not the wall thickness, I'll do that later.

[Erich Stahler]

jonbarrett said:

Strangely enough I measured the diameter yesterday but not the wall thickness, I'll do that later.

Thats fantastic Jon, those pictures will be a real help, now I just need to know the answer to the question your original posting was asking

I take it the compression coupling you are refering to is the fitting that is made onto the end of the flexible hose?
I have a feeling as the pipe is a metric size you simply specify pipe fittings for 8mm pipe.

[GreenV8S]

The existing fitting looks to be in good condition, so you could simply cut the old crimped end off and refit the new hose onto the original fitting with screw or crimped hose clamps.

[jonbarrett]

Peter

I wondered if that would be possible. I guess there is no harm in trying. I have a Pirtek nearby with a crimping machine. In fact they made a new high pressure hose for the cooler to fuel rail section. Thanks for the idea.