Add a breather to the fuel filler pipe?

[JonB]

Hi

Where can I get a suitable tap to route a breather to the filling pipe on the Elan +2? I presume it would be a screw in affair with a nut inside the filler pipe and gaskets either side, but I'm not sure what it's called or where to buy one.

Come to think of it, is this even safe?

Cheers
JonB

[prezoom]

If you can get access to the parts manual for a late Plus2, you can see from the drawing, the Federal model has a different style fuel tank. There is a catch/overflow separate tank fastened to the top rear of the fuel tank. This auxiliary tank has a breather tube from the top of the fuel tank to the aux tank. The aux tank has a line from the bottom, back to the fuel tank to return any fuel overflow. If you do not have a parts manual, you should try to find one. The drawings alone are worth their weight in gold.

There is also a breather line from the aux tank that leads up the left side of the car to the front, that attaches to a charcoal canister. There are two (2) lines from the charcoal canister, one (1) leading to the air intake tube from the air filter housing, and the other going to a splitter that feeds the Federal Stromberg carbs. These lines consume the fuel fumes from the tank, making a positive method of eliminating fuel fumes, rather than the two (2) loop over lines that cross above the rear windscreen and exit to atmosphere. There is no reason that a similar tank could not be added to the original style tank, if a Federal tank could not be located. A return fuel line from the added aux tank could be spliced into the fuel line to the carbs at the bottom of the tank, thus not having to penetrate the existing tank.

There currently is not a way that I am aware of to connect the carb line to Weber carbs, but I am working on it. Weber 152G carbs have ports that are blocked off with screw caps that could possible be used to pull the fumes back into the engine. A series of one way valves, as described on sidedraftcentral could possible be used to prevent cross talk between the individual intake throats. They would also act as a flame arrester in the case of a kickback from the engine.

[Chrispy]

Excuse my ignorance, but what is the benefit of a breather? Allow easier filling of the tank?

[JonB]

Well first off, I don't have the Federal model, mine's a U.K. Spec car.

A breather performs several duties.

• Allows air to escape when filling the tank.
• Allows air to enter to replace fuel as it is being used.
• Prevents dangerous pressure changes in the tank due to ambient temperature changes.

[jono]

Jon,

I made one using a barbed brass hose fitting with a curved adapter on the inside of the filler neck, then 2 fibre washers and a thin brass nut.

I am not aware of anyone making such a fitting specifically for the Plus 2

Jon

[prezoom]

JonB

I offered a solution that the factory employed to prevent fuel spillage from the vented fuel cap and the fuel smell that often fills a garage. Constructing an expansion style tank and fixing it to the non Federal style tank should be a very simple task. Others have tried to eliminate the fuel smell by sticking corks in the ends of the vent tubes, to which I believe is a temporary solution to the problem. The Miata back flow preventer is only part of the solution when maintaining the vented fuel cap. The existing caps vent can be blocked and the solution I suggested fixes the fuel spillage and smell issue.

Before shutting the door, try finding the picture in the parts manual where you can see how Lotus solved both problems. All in all it is a very simple solution to what is an annoying issue.

As far as bodges go, the venting system on my car created problems that caused the complete melt down of the engine, thus its bargain price. The DPO used a cutting torch to create additional clearance for the exhaust header at the chassis. In doing so, burned through the vent line from the tank to the charcoal canister, which they also trashed. The melted nylon line completely blocked venting from the tank. Only an electric pulse fuel pump prevented the fuel tank from collapsing inward. That and a non vented fuel cap leaned the engine to the point of melting the crown of the number one piston. What little fuel that was reaching that cylinder, along with oil infused air in the lower block, created an efficient torch in of its self. Enough so as to melt the center of the auxiliary venturi in the Weber. In over 50 plus years of running Weber carbs, I have never seen anything like this. The correct venting system to the charcoal canister (thanks Ted) restored a filtered breather to the fuel tank. Currently the carburetor end of the vent is feeding fuel fumes to the air box with a temporary flash protector.

Eric is correct. Bodges through the years kept cars running and on the street. Some of those bodges were basically harmless, others were not.

[Foxie]

Well first off, I don't have the Federal model, mine's a U.K. Spec car.

A breather performs several duties.

• Allows air to escape when filling the tank.
• Allows air to enter to replace fuel as it is being used.
• Prevents dangerous pressure changes in the tank due to ambient temperature changes.

It should not allow fuel to leak out if the car turns over

[JonB]

Well first off, I don't have the Federal model, mine's a U.K. Spec car.

A breather performs several duties.

• Allows air to escape when filling the tank.
• Allows air to enter to replace fuel as it is being used.
• Prevents dangerous pressure changes in the tank due to ambient temperature changes.

It should not allow fuel to leak out if the car turns over

Good point, I forgot that. And it shouldn't - that's why there are two breather pipes looped over the top of the car.

[miked]

I pulled out the filler neck and cut a piece out of the side. I then made up a flat piece of steel with wings/tabs and soldered it back in to create a small flat landing area below the circumference of the tube. I did the same as Jono with a barbed screw in hose tail but soldered a thin turned down nut on the inside of the flat landing area. I think I actually turned a small spigot on it to locate and solder easier. This allowed the filler to be pushed back into the rubber grommet (nothing sticking proud) and then the hose tail to be screwed in position after. If you looked down the neck you could just see it on the inside. No impedience to filling.
I had photos but lost them. I think I made the nut from a cut down pipe joint.

Mike

[miked]

While you are at it why not sort out you fuel filler cap as Plus 2 caps are notorious for leaking fuel down the back wing. There was a good posting about it which I added photos. I will locate and bump forward. Not sure how to include using tablet.
Mike

[The Veg]

I did this and the Mazda anti-backsplash valve mod recently. I had a local radiator shop braze a threaded bung into the neck, into which went a thread-to-barb nipple. I also had them grind it down as near-flush as possible so I could still get it through the gasket. I won't know how well any of it works until I get the car back together enough to drive, and I have no prior experience with the car with which to compare so I did these mods on faith from the good things I read here.

[JonB]

If I were you I'd get a new lid, or make a new seal. All that silicone looks hit & miss. Does it seal?

I was thinking of adding a breather near the top of the rubber pipe section, but I prefer your solution. Higher is better, right?

I discovered yesterday that the car had a new tank put in around 25 years ago. Maybe it is leak free, but I know there's been some fuel on the sound insulation felt under the driver's side rear seat. Doesn't smell fresh though.

[The Veg]

I quite agree about the seal- you're seeing a bodge done by a PO. No idea how well it seals as the car was inoperative when I bought it and still is. I did find what looks like a new seal amongst the stuff that came with the car- it's a ring of black sheet rubber that looks just about the right size. Guessing it needs to be fixed in place with a good strong adhesive.

Higher does seem better; I've got the nipple connected to one of the tank vent spigots less than a foot away at similar height. A little fuel my slosh out through it in a corner, but it'll just go down the filler which I figure will be holding some fuel anyway since the elbow is down below max fill level. The Mazda valve is in the top of the elbow so at full tank a little fuel will be above it. Time will tell how well this works, but luckily my paint is manky enough anyway that if some slosh-out occurs it won't be the end of the world and I'll know that some improvement to the setup needs doing.