Petrol Breathing - Ken Inds Design - Club Lotus

[terryp]

Hello
Firstly Happy New Year to everyone!
My News Years resolution is to sort the petrol smell to my +2. I don't mind , too be honest I can hardly smell it but Catherine my wife says its horrible!
I decided that the Ken Inds Design may be the way to go but a few questions .........

What size ID pipe can the small bore be and presumably it would have to be petrol pipe?
Can the large bore to the top of the cap be 8mm ID as I want to use one of these as I have no welding/braising experience http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... K:MEWAX:IT
Do you think that a non return valve in the small bore breather would improve things even better?

Thanks!
Terry

[stugilmour]

Hello
Firstly Happy New Year to everyone!
My News Years resolution is to sort the petrol smell to my +2. I don't mind , too be honest I can hardly smell it but Catherine my wife says its horrible!
I decided that the Ken Inds Design may be the way to go but a few questions .........

What size ID pipe can the small bore be and presumably it would have to be petrol pipe?
Can the large bore to the top of the cap be 8mm ID as I want to use one of these as I have no welding/braising experience http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... K:MEWAX:IT
Do you think that a non return valve in the small bore breather would improve things even better?

Thanks!
Terry

Happy New Year to you as well Terry. For reference, and to keep the stuff in one place, I have added a few links below on the background you are referring to.

I have done a similar mod to my Plus 2, and no real odor issues any more, at least greatly reduced. Schematically I followed Ken's idea, but I made up a small manifold of screwed together brass fittings that is screwed directly into the modified fuel filler pipe. This keeps the various tee fittings above the top of the fuel tank, which is the key issue. I got the modified fuel filler pipe (similar to the pic in the link below) off eBay and installed a new fuel cap to it. You should be able to have one made up pretty easily by a local welder.

I don't think the eBay fitting you have highlighted above will work very well, and would recommend biting the bullet and getting the metal filler pipe modified with a screw boss to take the fittings. The nipple arrangement you are thinking about will have to be installed inside the filler pipe when it is in place, which would be pretty awkward and will be difficult to tighten up. The Spyder devised filler has a threaded boss attached (brazed?) to the metal filler pipe, which does not appreciably add to the outside diameter of the filler pipe. This allows the pipe to be inserted through the hole in the body (just). The hose nipple is screwed in place from inside the boot after the filler is positioned, and has to be removed to fit the filler through the body hole. It's pretty tight in there, and I had a bit of difficulty fitting a hose clamp above the boss to keep the fuel filler cap correctly positioned.

The eBay fitting mentions sealing to flat surfaces; O-ring may not fully seal to the ~2" diameter filler pipe due to curvature. Seems to mention it is for water hose; not sure if good for fuel service?

Don't have exact hose diameters I used to hand, but the small hose that is overhead is about 1/4" ID or so and is rubber flex hose not metal fuel line. I selected the size to fit inside the larger replacement rubber overhead hoses I mounted in place on both sides of the car. I was able to feed the smaller hose through the larger hose; if you can't do this trick with the aging clear plastic stock vent tubes the head liner has to be removed to provide overhead access. The small hose is only required on one side. I installed replacement large diameter rubber vent hoses on both sides as per the stock setup only because I wasn't sure my mod would work; only the one small overhead hose ends up being used.

The large hose to the fuel filler has to be a fair size to allow for re-fueling. Not sure of the exact size I used, but thinking 3/8" or 1/2" ID? If really helpful I can probably find a scrap of the hose in the shed to get the exact size.

Here is the link to the Ken Inds document:

elan-plus-f13/vent-tubes-predicament-breather-pipes-t18171.html

And to the Spyder filler picture:

elan-plus-f13/fuel-vent-t14212.html

And some pic's of the stock configuration:

elan-plus-f13/fuel-tank-dimensions-t19667.html

HTH

[terryp]

Stu
Thanks for all the info.
I know that fitting isn't ideal, the problem I have is that I would have to send my filler back to the UK to be modified. I though that the eBay item together with either some fibre or copper or spark plug type washers would take the curvature out and do the trick.
I've also looked at a banjo connection that could be bolted on the side with a nut in the filler neck. I can get this in 10mm diameter ID outlet. I'm concerned that this acts as a eturn on the fuel being pumped in and may have to be bigger?
For the branches I can use nylon hose T's which can lay on the top of the tank which should be quite neat.

Cheers
Terry
PS What I can't understand is that on my old Ginetta G15 with the tank in the front, there was no breathing at all. A filler in, and a pipe coming out. How did that work???????

[alaric]

Hi Terrp. I presume the breather pipes are required due to the shape of the tank and where the filler pipe goes into the tank relative to the max fill level. On cars like the old mini the filler was at the top of the tank so breathing could be done there.

Sean.

[Higs]

If you do not want to weld anything to the filler pipe then this type of thing may get you there:

http://content.yudu.com/Library/A1nye6/ISSUE14CATALOGUE3rdJ/resources/index.htm?referrerUrl=http%3A%2F%2Fwww.cbsonline.co.uk%2Fconsumables-47-c.asp

Go to page 186 and see item at top left. With a thick gasket this might work.

Richard

[Jason1]

Hi

Welding in the fitting is a bad idea as to renew the rubber neck seal the filler needs to come up out of its position through the body. The best thing to do (in my opinion) is to drill and tap a thread into the neck and screw the fitting in; that way when you need to renew the seal you can just unscrew it. The old thread above is a good read on this subject.

Jason

[stugilmour]

Stu
I've also looked at a banjo connection that could be bolted on the side with a nut in the filler neck. I can get this in 10mm diameter ID outlet. I'm concerned that this acts as a return on the fuel being pumped in and may have to be bigger?

I took a look and cannot see the hose to measure it, but looks to be about 3/8" ID, so 10 mm ID hose should work if this is what will fit on your proposed attachment. The fueling cannot be done at full speed for the top quarter or so of the tank, but it works OK. It definitely pushes some liquid fuel through the return line during fueling. The fuel level tends to back up to above the vent opening in the fuel filler neck during re-fueling, so some liquid periodically gets in the vent pipes.

The thing Richard found looks better, and sounds like your alternate fitting? If you can get something similar but with female pipe threads looking out (rather than a full length barb hose fitting) it would work even better. This is essentially how mine is; ends up similar to what Jason is getting at but the permanently attached fitting provides better female threads to accept the barb fitting. Basically it looks like who ever made mine cut a round hole in the filler neck and welded in a nipple with female threads facing out. As Jason mentions, the barb fitting (or elbow in my case) has to be removed to remove the filler neck from the car, so the permanently attached fitting can't stick out more than 1/4 inch or so.

I think Lotus didn't want to use a vented cap to prevent fuel staining on the fender and trunk lid. As it is I have managed to overfill the car on occasion and the fuel runs all over the place, I wonder how well sealed the cap is anyway. Anyway, like Sean says, the vapor at the top of the tank is trapped separate from the cap, so it needs independent venting.

[terryp]

Thanks everyone, looks like my smelly +2 will be a thing of the past soon!

Thanks again
Terry

[miked]

Hi Terry, I haven not read all the posts so forgive me if I have repeated but I cut into my filler neck and made a little flat landing plate with wings out of a piece of steel and then soldered it and a (turned down) threaded adapter. With being below he circumference it all slid into the grommet nice and was able to screw a brass pig tail in. I did the whole mod' as per the article and am now smell free. I was quite pleased with the fact that I got a good job with solder. I noted that the top cap part was soldered to the tube (by Lotus) so thats why I did it.

Mike

[Higs]

Hi Terry, I haven not read all the posts so forgive me if I have repeated but I cut into my filler neck and made a little flat landing plate with wings out of a piece of steel and then soldered it and a (turned down) threaded adapter. With being below he circumference it all slid into the grommet nice and was able to screw a brass pig tail in. .....

Mike

Mike

This sounds promising but could you gives us a few more details? Did you cut out a slot in the filler neck (presumably making two parallel cuts)? You then made up a flat piece to go in this slot with "tails" on each end to wrap back round the filler? Did you need to build up the sides of the plate to fill in the gap between the flat plate and the curved filler?

More info or a drawing would be great.

As a further simplification to the full scheme, can I suggest that if you believe your current breather tubes are in good condition, then all you need to do to make Mike's modification work is to run a short piece of pipe from the filler neck connection to a "t" piece inserted into the nearest breather pipe. Then all you need to do is to make some plastic plugs for the ends of the breather pipes (where they come out of the cat in the wheel arch) and finally drill some very small holes through the plugs. Job done.

This works because you are effectively separating the two functions of the breather piping: the requirement to let air out from the tank in order to fill it; and secondly the requirement to deal with expansion / contraction of the fuel/air due to changes of temperature.

The former job can be done from one side of the tank only as all petrol stations are flat and level and therefore so will the car be. The latter job needs breathers from both sides of the tank because a car might be parked on a side slope (and if there was only a breather on one side then expansion of the fuel/air in the tank might push out liquid petrol if the breather was covered by the fuel level).

To my mind the scheme of joining the breathers together is over-complex unless you think that they might be leaking.

My last thought is that the neatest solution would be to put a breather pipe into the tank through the filler neck itself. It would need to go into the tank and up to the top of it. This breather would then fulfill the first role of venting the tank when filling it. I am trying to think of a way to fix this pipe in place. Then all you would need is the plugs in the ends of the current breather and the problem is solved. Neat but so far not easy!

Richard

[miked]

Hi Richard. I did a rough sketch and scanned it in but don?t know how to render it down. It said this.

the image must be at least 0 pixels wide, 0 pixels high and at most 1024 pixels wide and 900 pixels high. The submitted image is 2927 pixels wide and 1796 pixels high.

If you can tell me I will post or PM me your email and I will send.

Yes, it was two parallel saw cuts across the filler. For the landing plate (from one piece of metal), I made small tabs that bent around the circumference. Made small circular tabs that bent upward to fill the circular gaps. Made these sit proud so the solder ran up against the sides. I the filed back after. I drilled the hole prior to soldering then I fitted a threaded insert at the same time. This was one of those pipe fitting hex things that I trimmed down to round on the lathe. I also made a spigot so it sat in the hole and encouraged the solder to dwell on it. Fitted on the car and screwed the pig tail in after. I did what the spec? sheet said about the pipe arrangement. All seemed very logical when I read it.

Mike

[rdssdi]

http://www.newton-equipment.com/

Try them for vent discriminators and roll over valves.

I used on my +2 which has a custom alloy tank with welded bungs (-6). Tank was made by Axminster Specialist Panels.http://www.andywiltshire.com/

Bob
1969 Elan +2
1968 TVR Vixen
1963 Jaguar MK2 3.4

[syrius]

http://content.yudu.com/Library/A1nye6/ ... s-47-c.asp

Go to page 186 and see item at top left. With a thick gasket this might work.

Richard

Hi
I think the inlet see on "carbuilders solution " page 186 its a good alternative If we dont want to weld somethink on the pipe .
thanks Richard.

A+
serge

[terryp]

I managed to get this little part. Don't know what its off but I beleive may be perfect or able to be adjusted to be perfect
http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... SA:GB:1123

Now to order the pipe and T's and then no smell

Terry

[Robbie693]

Hi Terry,

What sort of hose or pipe do you intend to use?

This thread may be useful if you haven't decided, the posts by Gerry are very imformative:

http://www.lotuselan.net/forums/elan-plus-f13/replacing-fuel-tank-t17910.html

Cheers

Robbie