Adding breather connection on fuel filler neck

[mbell]

So I am in the middle of implementing the fuel tank breathers modifications on my +2. I am now at the point of needing to modifying the fuel tank filler neck for the breather connection. So far today I visited Lowes (aka B&Q) twice and the local plumber merchant and have come up empty handed on what I think will be a working solution. I can't even find any thing on McMaster-Carr!

A few hours searching on here have found a few dead ebay links, talk of braising/soldering/welding a nut/boss inside and just drilling/tapping a thread for a screw.

I may be over thinking this but it seems to me the drill and tap method won't give enough material for a good fix/seal. The nut method would need a curved nut/boss, that I don't seem to be able to find any and I don't have a lathe to make one. I also don't have a welder to weld it on.

Can any one provide more details on how they tackled this with just basic tools (drill, tap set, solder iron) or links to the hardware you used for this?

Thanks,

Mark

[rgh0]

I have not personally done it but if trying to do it without specialisr machining or welding equipment I would try the following.

Find an AN hose fitting of the diameter wanted with a thread one end and hose connection the other
Drill a suitable hole in the side of the filler for the threaded end of the AN fitting and locally flatten the area with a hammer on the outside and suitable shaped lump of steel held on the inside.
Using nuts and washers and suitable sealant / fibre washers fix the threaded end of the AN fitting to the filler neck and the vent hose to the hose fitting end
Done but think about how you will assemble it in the car before you drill the hole !!

cheers
Rohan

[Spyder fan]

Mark,
I may be able to save you a load of faffing around.

My +2 breather system was modified by Spyder when it was converted to zetec.

I have a filler neck for a +2 drilled for a breather with a welded in tapped section sitting here on my desk. It was modified by Spyder I believe its 3/8 bsp.

I changed my fuel filler cap to a Monza style last year which requires a different filler neck, so this one came off my +2.

It doesn't weigh a lot with the cap removed, so if you want to pay the postage to me via my paypal account and donate $10 US to lotuselan.net I will remove the cap and post the neck to you via Royal Mail small packets airmail.
I just checked the postage and it's ?4.80 (roughly $8 US) so that makes a total of $18 if you are interested?

[stugilmour]

Wow, great deal for you Mark! I used a similar bit that I got from eBay UK; believe it was also originally done by Spyder. Note the way they did it with a boss that sits essentially flush to the outside of the neck. If not done this way the neck will not fit through the hole on the fender, as Rohan cautions. I was trying to find a pic of mine, but Alan beat me to it.

As we were looking at the issue, I checked on Ray's parts drawings again. It looks like the post 1971 Federal system with the vapour recovery system uses a different filler neck with the required take-offs for venting. Hard to tell from the drawing, but it looks like the neck and cap are a separate bit and the vent portion is fitted from underneath in the trunk.

I was also looking around for you, thinking a model of the Europa TC Federal might have a vented filler neck. Not sure, but I think the Europa might use a 2" neck, where i think (from memory) the Plus 2 neck is 2 1/4"? I have asked some Europa dudes on a different forum to see if they have a part that would work.

Anyway, the bit Alan has will work great. Just trying to follow up on a source for the future for guys. Alan, will Sean and Andy still make up the modded necks for guys or supply them already modded?

Cheers! Happy new year to all.

Stu

[mbell]

Thanks Guys,

Ronan your idea is exactly what I had been thinking of doing. I just failed to find any suitable fittings. The AN look like a possible solution, I will probably have to buy of the internet thou that adds a level of uncertainty.

Alan, that is a very generous offer and I be silly not to take you up on it.Thank you. I was thinking about making a donation but being my lethargic self about doing it. So this is very good motivation to get on an do that. I'll PM you for addresses etc.

Looks like I need to find a suitable BSP barb connection, the standard ones available over here are all MIP (aka NTP) that I don't think will fit correctly.

Stu, I actually happened to be helping a friend remove the (extremely rotten) fuel tanks from a Federal TC Europa a month or so again. The filler neck did have a pre-fitted barb and I assume the filler neck removed to free them from the body. As I couldn't see how else they could be removed.

The barb however was a lot smaller than would be required for the +2 setup, probably 1/4". So I don't think it is an option for the +2.

I didn't measure the neck on the Europa so not sure if it was 2" or 2 1/4". As I have the neck off my car I can confirm that you are correct that it is 2 1/4" diameter.

Thanks again to you all and a Happy New Year.

Mark

[stugilmour]

Excellent Mark. I can't recall what the threads on mine were, but I picked up all of the fittings easily at our local plumbing supply. Maybe just wait to get Alan's neck and see if you can match it up?

Stu

[Jason1]

lotus-carbs-f40/fuel-vent-t14212.html

Here is an old discussion we had on this many moons ago that may be worth a read?

[Spyder fan]

Mike,
I got your PM and I have replied with my Paypal details. I will be at my garage this weekend and will pull the cap from the neck ready for posting on Monday. I will also have a look at the breather connection on my +2 and see if I can fathom which part is needed to connect to the threaded boss, maybe take some photo's as well.

Happy New Year everyone!

[mbell]

Excellent Thanks Alan. Look forward to receiving the part and completing this mod.

Thanks for the link Jason. I had given that thread a read through before but couldn't find the critical information I was after, i.e. specifics of a suitable connecter to modify the filler neck without needing a lathe and welder.

Cheers,

Mark

[andywatts]

Mark - have now posted a couple of pics on your original post (at http://www.lotuselan.net/forums/lotus-carbs-f40/lotus-elan-fuel-system-overview-and-improvements-t30305.html for other readers). My filler neck is similar to the Spyder one, but I re-invented the wheel, and also found the problem that the fitting cannot project at all from the filler neck, or it won't go on the grommet which seals the neck to the body.

Andy

[mbell]

Thought I just post to close this thread out. I received the filler neck from Alan (thanks again!) And ordered the 3/8 bsp to half inch pipe adapter. One of those things where postage costs 2x the bit you buy.

Fitted the neck and made the final collections. Not a lot of fuel in the car but certainly not noticing a petrol smell in the garage.

[Ian T]

I am about to make this modification to my Plus 2 and have raked through all the threads I can find on the subject - lots of them. I have drawn a picture of what I intend to do and hopefully it will make sense to everyone here who has done something similar.

I do have a couple of questions though. Why must the bore of the whole over-roof breather be small? I realise that a continuous small bore pipe over a long length (in this case anything up to 3.5m by the looks of it) will also impede gas flow due to length, but couldn't an acceptable alternative simply be to reduce the bore at one or other end and avoid having to thread it over the roof?

Hopefully the attached drawing makes sense, I have listed the main shopping list of items I have fairly readily found on eBay.

I am currently proposing to braze the threaded boss onto the inside of the fuel filler rather than weld, simply to avoid any access issues I'd encounter trying to weld it from the inside of the filler neck.

Can I confirm the filler neck is made of a form of stainless steel rather than galvanised?

Thanks,

Ian.

[fattogatto]

Drill a hole the appropriate size to start the 1/8 NPT end of a AN-3 or -2 fitting. Screw the fitting in until it is tight. Use a dollop of Loctite Epoxy on either the inside (cleaner appearance if you can reach it) or the outside to prevent it from coming out. Then use a -3/-2 line to wherever you want your breather to go. Or, just leave the fitting as the breather. Or, you can try a bulkhead fitting in -3 or -2 size.

[miked]

Solder works fine on the filler neck. I cut in and made a little landing area and soldered it and the fitting in. I think you will find that the filler cap fitting is soldered to the neck.