Teflon fuel lines might stop carb flooding?

[Waynebaby]

I am struggling with repeated flooding of the150 CDSE Strombergs on my Mk3 GT6 (one or other of the carbs gushes fuel at least once a month) and on every occasion the culprit seems to be black particulate material jamming the needle valve. I've fitted an in-line filter just before the copper fuel line bifurcates at the carbs and so I'm pretty sure that the source of the material must be the short lengths of rubber fuel pipe attaching the copper pipes to the carbs. I've changed the rubber piping but to no avail and so I'm beginning to wonder if what passes for petrol these days is attacking the rubber. Has anybody had experience of fitting teflon lined fuel hose?  Any other suggestions for dealing with this problem would be gratefully received (I've fitted new needle valves, the float height is correct and the floats aren't leaking). 

[Guest]

Hello.

 

Are you certain that the needle and jets are centred properly ??

 

It will be worth removing their "hats" and looking very carefully as you lower the piston, it does not take much to start causing problems - one of which you have alluded to.

 

When you removed the old needles, was there any excess "rubbing wear" on the needle itself - worth checking with a magnifying glass to make sure.

 

If you are happy that they are centred properly , then you have nothing to lose by changing the hose. In any case, as it's such a small amount you may as well do that at the same time. 

 

Unlike France where some of their fuel has 10% ethanol, the UK is nowhere near that - thank goodness. I doubt very much that the quality of fuel you are using (provided it is from a decent source) is the problem, I believe it is with the car itself.

 

I would also change the in-line filter every month at the moment and see how you get along. It is also possible that the inner wall of the fuel tank has shed a bit of lining, then broken up in to fragments. This will in time settle and the fuel filter will assist in preventing those fragments getting through.

 

You may even consider getting a better style of filter where the gauze can be washed and reused (these tend to ne the glass style types), the benefit of that is obvious but also the micron level (which allows particles to pass) tends to be better than the usual plastic paper element types.

 

Just some thoughts.

 

Good luck.

 

Regards.

 

Richard.

[Simon]

I bought some new valves for my 150 from Berlen and found they were sticking open. CW said he stopped supplying due to this, but when I spoke to them they said they had no returns for them. They were going to send me replacements but were OOS and gave me the option of ones with sightly bigger valves or 150's used on Spitfires (I believe), they said these have better valves and a mesh filter attached to them, which it it didn't fit can be cut off. I went for the 150's but have not fitted yet.

[Pete Lewis]

way back many manufactures used a self grip nylon mix hose connector , certainly Rootes used them because of the  olive /flare and rubber hose shaving problems   Richards  Alpine may have them .??

 

the needle valve with the gauze is a straight swap for one without it   I have  fitted loads .

 

i guess by your term 150s you are on the valve size of 1.0mm or 1.5mm  hence 'bigger' ??

 

a 1.5 mm valve will need more floatation effort to close than a 1mm  valve with the same float

 

all 150 cd/ cds /cdse /  have the came valve fitting / float and thread 

 

someones talking sales blurb !!!   spitfires in UK never had strombergs , not even the 12 litre versions   Ha !

 

if in trouble use carburetor exchange   leighton buzzard.    http://www.carbex.demon.co.uk/

 

small but helpful give them a call  

 

Pete

[JohnD]

The correct type of rubber to use with modern fuels is "Viton".

Not cheap - £6/meter?

Model shops sell it in that 'small' quantity.

John

[Waynebaby]

Many thanks to everyone for their help. I'll probably start with John's suggestion of checking what my fuel hose is made of. It is new only inasmuch as it has never been on a car before, but as it has been sat in my garage for some time it is of doubtful provenance! My float valves are 1.5mm although when I got a carb refurb kit they came with 1.75mm valves. These stuck open just like Simon's and so I've refitted the old valves. 

 

Wayne 

[Pete Lewis]

Viton  was said to be real nasty  stuff if it gets burnt

     never touch it with a bargepole if there's been a fire around it .

        we had this in some head gaskets materials and  H & S  field day . ........ the cure was  cut the fingers off.    

 

           seems this was all a bit scaremongering  and  thankfully  better clues are supported  here  

 

              http://www.hse.gov.uk/mvr/topics/fluoroelastomers.htm

 

Pete

[JohnD]

Lots of materials are 'nasty' if burnt, and others just as 'nasty' in normal use!

NOT Viton rubber, which is harmless in normal use.

 

The last paragraph of the webpage you linked to says:

"It makes sense to wear suitable gloves to stop getting you hands dirty when dealing with burnt-out vehicles, so even if there was the tiniest chance of HF being present, you would be protected."

With the deletions, that should be standard practice!

 

Amateurs like us usually forget, but in industry and the motor trade, any sensible mechanic wears vinyl or full mechanic's gloves, or at least barrier cream.

Apart from anything else, they make hand cleaning afterwards so much easier.

 

John

[Simon]

Many thanks to everyone for their help. I'll probably start with John's suggestion of checking what my fuel hose is made of. It is new only inasmuch as it has never been on a car before, but as it has been sat in my garage for some time it is of doubtful provenance! My float valves are 1.5mm although when I got a carb refurb kit they came with 1.75mm valves. These stuck open just like Simon's and so I've refitted the old valves. 

 

Wayne 

Phone them up and complain and get them to send you a new pair.

[Pete Lewis]

Ah ,, Rozalex and degraded swafega thats gone runny bring back some old memories

 

 

 

pete

[Clive]

Correct hose rating is R9, do not accept the older R6 as "that is what we always supply" as it isn't suitable for alcohol-containing fuels which is what we have to use.

 

I ended up getting a roll of Goodyear greenshield from the states. Luckily a friend was about to come over and visit, saving the hefty postage and customs charges!

[Waynebaby]

Following Clive's message I've just checked the hose fitted to the car and it seems I'm using R6 spec hose. Many thanks Clive.

[Pete Lewis]

See my rogues gallery post about stromberg needle valves with missing outlet holes

 

mKe sure the ones supplied are correct

 

pete