Lotus Elan

Petrol fumes.

PostPost by: rdssdi » Thu Dec 20, 2007 1:21 am

The Mocal breather vents have a rubber fuel line attached. I attached an AN -6 90 deg. elbow barbed to the vent and pushed on the vent hose. I route it directly to the wheel arch exits. Crossed above the tank rather than above the rear screen. I have attached a photo that details the hose hook up. I have since added a hose clamp.

I have a roll of the ground strap. It will work properly but does have an unnecessary "heavy duty" look. It will be hidden behind the boot / tank panel.
Bob
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PostPost by: Over Steer » Fri Dec 21, 2007 12:03 am

nice setup M8 :!:
Jan

1963 23B
1969 Elan + 2
1973 Europa JPS Special
2004 Prep'ed Lotus Exige
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PostPost by: mikealdren » Fri Dec 21, 2007 9:35 am

Bob,
looks excellent.

I'm sure that the pressure settings on the Mocal valves will ensure that they are normally shut and prevent petrol vapour escaping in normal use. After Gordon's post, I guess my only concern is whether the back pressure slows the tank filling. Have you tried it yet?

By the way, I looked up the carbon filters on the 'net. We don't have the rule in the UK so it was news to me. Looks like the US is very keen on reducing emissions from fuel eveporation through fuel tank breathers, must be your hotter weather. Driving gas guzzlers and then worrying about such small issues, have I missed the point?

Mike
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PostPost by: rdssdi » Fri Dec 21, 2007 3:25 pm

I assumed that evaporative emissions were responsible for a large part of air pollution and relatively easy to control. With hysteria the norm and environmental crazies everywhere it is difficult to tell where the truth lies.

I have not filled my tank but I cannot see why the breather vents would alter filling ability.

I will soon have the car "on the road" (at least 3 blocks from the resto shop to the upholstery shop). I will let you know.

Bob
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PostPost by: gordonlund » Sun Dec 23, 2007 4:23 pm

If you squeeze the filler pump handle too hard once you are passed half full the petrol will fly out and soak you. Take the polish off the car body as well not counting the fire hazard. It does this anyway with good full bore breathers and can only be worse with restricted breathers. Can take ages to fill tank to the brim. Takes the edge off having a quick release filler cap don't you think?

In passing, how much petrol should a +2 tank hold, the manual says 10 gallon (Imperial) a few more American. I have only managed 9 and a bit in mine.

Gordon
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PostPost by: rdssdi » Sun Dec 23, 2007 6:48 pm

When the tank passes approximately half full, the filler neck tank attaching point is "covered" by the tank contents. The fuel level in the filler neck must be above tank level to displace fuel in the tank and continue filling. I feel that whatever the vent sizes, one can add fuel at a higher rate than what can be displaced.

The head or difference between the filler neck fuel height and fuel tank fuel level diminishes as the tank fills reducing flow rate into the tank.

I contend that the vents are of less importance for fuel filling rate than the tank design. A poor design at that.

Bob
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PostPost by: rdssdi » Sun Dec 23, 2007 11:11 pm

The prototype +2, The Meteor, had the fuel filler on the "sail panel". That placed it well above the fuel tank. Reports were that the filler in that location would leak fuel over the car.

It is a sensible location. A bit of engineering and possibly a fuel filler door would have made it viable.

Bob
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PostPost by: lotuselanman » Sun Jan 13, 2008 8:13 am

:D :D

Gidday, This is very interesting topic.
I like the principal of the 'Mocal' as far as venting to the atmosphere as long as the cannot create a vacum in the tank and restrict fuel flow. As far as filling the tank, a simple dual vent system with a line from each end of the tank merging to a single line to a point high on the filler neck, this would allow displaced air to vent in the filler neck.
Sounds good to me.
See ya,
Les
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