Lotus Elan

+2 fuel vent

PostPost by: rdssdi » Sun Jan 14, 2007 9:46 pm

I see theat Spyder Engineering has redesigned the +2 fuel tank vent for their Z-Tech conversions. Apparently they vent the tank to the filler neck.

I would like to modify my vents as the original is prone to allowing vapors into the car.

I am concerned as the original crossover vent tubes prevent leakage in the event of a roll over. It should not leak in any position the car is in in the event of an accident.

With the vent in the filler neck that safety feature has been defeated. Also would a vented cap now have to be used?

Has anyone addressed this issue?

Suggestions?

Bob
1969 Elan +2
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PostPost by: chrishewett » Sun Jan 14, 2007 9:51 pm

I have converted my car to the spyder system. I think it works well. If I were to roll the car I think that fuel leaking would be only one of the many things that would be ruining my day.
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PostPost by: andyhodg » Sun Jan 14, 2007 10:11 pm

Bob

I have put the vent system in featured in the Club Lotus magazine about a year or so ago.

This brings the two vents from the side of the tank together centrally above the tank. From thic point there is a small bore pipe (I used 4 mm hydraulic / pneumatic plastic pipe) whis id routed through one of the old vent pipes. Also from that central point there is a large bore vent pipe that is taken to the vent inserted in the side of the filler neck. This system allows the tank to suck air through the small bore pipe when the engine is runing. The vent to the filler neck allows the top half of the tank to vent when filling the tank.

If the car did turn over the only leakage would be through the filler cap.

I find it works well althought there is more leakage from the filler cap than there used to be. However I did change the cap at the same time so it could be due to the new cap.

It has certainly reduced the petrol smell in the garage.

Good luck Andy
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PostPost by: rdssdi » Mon Jan 15, 2007 3:39 am

I am having a difficult time posting this message. This is my third attempt.

I contacted Spyder Engineering regarding their +2 vent/filler neck. My e-mails were bounced. Apparently I am "black listed" by their e-mail server for spam. I do not understand this. I faxed sean at Spyder and am hoping for a reply.

How does the tank vent through the filler neck. It appears that the cap is not vented.

Would a discriminator/check valve as used with safety fuel cells work to prevent leaks i n the event of a roll over?

Bob
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PostPost by: Jason1 » Mon Jan 15, 2007 7:24 pm

Hi

I contacted Spyder about 6 months ago about the filler neck and was told they are no longer do it. They used to do the breather and provide a removable ally plug in the neck to stop the spillage.

They said as the necks were of varying sizes it was hard to get a good seal?

It would be easy to drill a hole on the neck, tap a thread and screw in a brass tail. I have checked on RS Components and the tails are only a couple of pounds. The plug is a lot harder as it needs to be machined.

I printed a page from their site when it was on there (I cant find it on there now) I will dig it out and try and post it on here so you can see what you need. :)

Jason
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PostPost by: chrishewett » Mon Jan 15, 2007 10:29 pm

I can't understand what spyder (Andy) is talking about. It sounds a bit " my eye and betty martin" to me. The neck I bought from him a year ago works fine. As you say it would be an easy job to do yourself if you could weld.
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PostPost by: Jason1 » Wed Jan 17, 2007 7:13 pm

Here is the scan of what Spyder used to do and their response to my email asking if they still do it.

Hi Jason,

We are discontinuing this part,
we have found that the filler cap housings vary to much for us to
manufacture a good fitting insert.

Sorry for any inconvenience caused.

Regards
Sean


S.Reeve



The vent part is easy as all you have to do is drill a hole in the neck, tap it and screw in the tail. Welding the tail onto the neck would be a mistake as you could not then later remove the neck if the rubber neck grommet needed replacing. Machining the plug is the tricky part :)
Attachments
neck.jpg and
Ex-Spyder mod
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PostPost by: rdssdi » Thu Jan 18, 2007 2:03 am

Its difficult to see what the mod is as your picture is grainy and not detailed. If they no longer supply this filler neeck what do they offer with their z-tech conversion. I thought it was needed with the z-tech FI system.

I cannot get in touch with Spyder as my e-mails are blocked by them as a ssource of spam. I faxed them and was told to e-mail but it still bounces. Spyder is not a very responsive company.

Bob
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PostPost by: Fubar » Thu Jan 18, 2007 8:00 am

Have you tried phoning them? My experience of Spyder is that they'll always take the time to talk you though any problems or queries you may have.

The tank vent system and the bung in the filler neck are two separate products - I suspect they still supply the filer neck with the connection for the vent pipe for the Zetec conversion.
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PostPost by: bcmc33 » Thu Jan 18, 2007 11:15 am

[quote="andyhodg"]Bob

I have put the vent system in featured in the Club Lotus magazine about a year or so ago.

Andy,

Can you remember which issue of the magazine it was in?

Club Lotus said they would send me a copy, but I need to tell them which issue.


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(1972 Sprint)
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PostPost by: Elanintheforest » Thu Jan 18, 2007 12:50 pm

Pardon my ignorance, chaps, but why is the Plus 2 vent system so designed? Is it simply that the tank is very high with respect to the filler cap so has to form a high loop under the roof to stop fuel spilling out of the vent? I was surprised to see the blooming great pipes disappearing under the hedlining. What would happen if they were blocked off altogether, and the cap seal had a small hole drilled in it to vent?
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PostPost by: chrishewett » Thu Jan 18, 2007 1:21 pm

I am now a bit confused on this one.
The +2 vent system is there purely so that you can fill the tank. As the feed pipe is half way down the tank it needs a breather at the top of the tank otherwise it would not fill past the filler. When I bought the breather mod from Andy he didn't mention anything about a neck plug.
As I have said before it works perfectly with the original cap and I no longer have a garage full if petrol fumes. I have no idea whether the cap is vented but I don't have any problem with vacuum buildup in the tank.
The mod in the Club Lotus magazine seems overcomplicated to me. However I will try and find the article and let you know.
Chris
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PostPost by: tdafforn » Thu Jan 18, 2007 1:51 pm

My theory about the +2 vent system and petrol smells is this.
Above petrol there is always petrol vapour. This vapour moves fills the breather until eventually it reaches the top. The vapour is heavier than air and so then falls down the otherside of the loop and collects on the floor givin a smell. In fact I have wondered whether this could lead to a sort of vapour syphon?
The spyder system is a closed system once the cap is shut so hence no problem
cheers
Tim
(with corks in the vents)
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PostPost by: chrishewett » Thu Jan 18, 2007 2:09 pm

Tim,
I agree. The loss of fuel by evaporation is so great that I don't see how it can happen unless there is some extra force in action.
The Club Lotus magazine with the article on +2 fuel tanks is issue no.4 2004
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PostPost by: rdssdi » Thu Jan 18, 2007 5:21 pm

What is the reason for the bung in the filler neck ?

Does it act as a roll over valve?

I am still puzzled as to how the filler neck is used as a vent if the filler neck cap is sealed. As fuel is used, without a vent, a vacuum will be created in the tank and neck. Retaining the original vent and attaching a roll over valve would allow air to enter the tank but not allow fuel or air to exit. If the filler neck seal is a bit worn or perished it may then function as a vent as it will let air pass the seal. When filling the tank, the open filler neck will allow air to pass through the vent into the neck as air is displaced in the tank.

I have faxed Spyder twice. I will no longer attempt to contact them. I find their lack of response strange as I have purchased a chassis, wheels, suspension arms and more from them in the past. I wonder why they do not produce a complete filler neck with vent and bung and not rely upon modifying customer units. Maybe there is a problem with the design?

I am also waiting for a reply from Andy Wilshire (sp?) regarding an alloy +2 tank.

Bob
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