Take a look at this thread on the S Registry:
Fuel Evaporation Control System

Basically, you route the line from the tank up under the cowl to the vapor collection canister, which is an empty chamber for 69. The exit hose from the box is then routed down the left side fender, next to the fuel tank, and out the front of the car using one of the body plugs behind the windshield washer pump

the other issue is whether you want to do it just like a stock '69, or want to use a later, improved system...

Thanks! Do you have a picture of the vapor collection canister? I am not sure that my car has one. I think it was removed by one of the many previous owners. I will check tonight when I get home but I am pretty sure that it is not present. I know exactly which body plug to route the hose through as I remember there being 3 solid body plugs and the 4th plug had a hole in it. I recall thinking "Now why is there a hole in this plug? There has to be a reason for this";)

on a '71-73 and maybe yours, it is about 9" long and oval in X-section - black and filled with carbon granules

when I asked CARB how long they lasted, they told me they would last decades unless liquid gas got into them (and killed the charcoal); they do sometimes burst after some decades of service

you can use any canister if you want, tho the oblong oval ones lay flat in the trunk better than others

you might need to do some field investigations at local junk yards or call a dismantler specializing in Porsches - maybe EASY or one closer to you?

Randy is referring to the later LWB car system. For 69, it's simply an empty chamber, up under the cowl. The EPA, DOT, etc hadn't forced the issue yet with charcoal and extra ventilation and all the rest. That stuff started in '70.

It shows up in the pictures in the link I shared, but here they are again. Looks like you know where to route it based on your missing plug...

Someone will have one of these vapor boxes for sale. I recommend searching around the SReg and you will find some, or maybe here at Pelican.

http://forums.pelicanparts.com/uploa...1353415475.jpg

http://forums.pelicanparts.com/uploa...1353415493.jpg

Thanks for the picture. I certainly do not have the chamber in my car. I will have to look around and find one. I am debating whether to add a charcoal cannister to keep the gas smell down in the garage. My idea is to set up everything correctly for 69 but to plumb in a charcoal cannister between the ventilation chamber under the dash and the "Y" where the line from the brake fluid reservoir connects. From the "Y" I can route the line out through the correct plug.

Kristoph,
I suggest you not bother with the charcoal cannister. Old 911's do tend to make the garage stink of gas, oil, and other things. That's part of their charm. But I really doubt that much if any of the gas smell is due to tank vapors. Most of it originates from the float bowls in your carbs and there is no way to stop that. If you just have the vent box mounted high up under the cowl it should be sufficient.

If you don't have the vent box, you could easily make a substitute until you find the correct part. You could duplicate the pre-'69 style, which is effectively just a loop of tubing going up high, then out through the trunk wall. A metal loop was used at the top, maybe with the idea of condensing vapors (?) in cooler weather. But you could fabricate just about anything to duplicate the concept.

DG

Neither of my 68s seems to have the chamber shown in the photo. I'm wondering if pre-69 (and maybe early 69), Porsche didn't use a chamber. On the other hand, maybe it was very popular to remove that piece as something unnecessary. After all, the 68s came with smog options that are hardly ever found on the car.

Aha! That's exactly what I have. Dave was replying as I was typing in my text about not having a box. Chiliheads think alike. :)

Hi Von,

Could you send me a picture of what the loop looks like? It would be much easier to replicate with a picture to work from;)

Its been really cool watching your thread. I get to start the mechanical side of the equation on mine very soon! btw the slate gray looks awesome.

I'll send you some photos when I get home tonight. I think I took quite a few when I removed it. I'll add in one with a ruler for scaling. It should be a simple thing to fabricate. Two pieces of rubber tubing and a bent 'u' out of copper if I recall correctly.

I am a big advocate of the charcoal canisters as my car reeks without one. There is also some danger of explosion in a closed garage.

Another issue is pollution. The poor evaporative control is why you see factoids that a modern car can be driven 100 miles or more and generate less pollution than an old car that is sitting still.

You have a wife, right? Be especially cautious about fuel vapor exposure (benzene) in the garage if she is pregnant, if you have children, or plan to. Old people need not worry much...

You can follow the diagrams for 1970-on.

There are usually two "empty" vapor tanks, depending on model. One is shown above - it is held up under the cowl by a flexible rubber band - an O-ring can be used for that.

Another is up under the LH fender - early tanks were translucent plastic, rectangular in shape. LAter tanks have a curve to fit up under the fender better and are a sturdy black plastic. The latter are easier to find as well.

I have never figured out which tank might have liquid in it and under what conditions, but my bet is that the fender tank has liquid gas from a fillup overflow until it evaporates and then winds up back in the tank. (Some modern cars have pumps to move evaporated and then condensed gas back into the tank). I'd also bet that the cowl tank should never see liquid fule, only vapor.

Inspect the tanks for cracks, maybe pressure test them. Use fuel vapor rated hoses only for the connections - do NOT use regular PVC (even if you filch it out of your lab). If original hoses are brown and hardened, then they should be replaced.

Good Luck with it.

oh yeh - P AG migrated the charcoal canister to the rear (engine compartment) sometime after 1975 (when it was still up front). I am not sure why, but maybe they got lower emissions.

I like to get as much wt. as possible off the rear, so put the canister up front (which ironically is concours correct for my year). IF you know why they moved it and add it to your car, maybe it makes sense to put it back there.

Here are some photos of my 68 vent system just before I removed it. If you decide to fabricate something similar, let me know and I'll get you some more detailed photos and measurements.

<table style="width:auto;"><tr><td><a href="https://picasaweb.google.com/lh/photo/Nvse7AU-DZfQ0bXC2aCNgtMTjNZETYmyPJy0liipFm0?feat=embedwebs ite"><img src="https://lh3.googleusercontent.com/-gUBEL28KBrk/UKw-9g-kvPI/AAAAAAAAA3Y/FZ50V1uZU7g/s640/DSC_8441.JPG" height="425" width="640" /></a></td></tr><tr><td style="font-family:arial,sans-serif; font-size:11px; text-align:right">From <a href="https://picasaweb.google.com/107685368595078804853/1106Porsche911OriginalState?authuser=0&feat=embedw ebsite">11 06 Porsche 911 original state</a></td></tr></table>

<table style="width:auto;"><tr><td><a href="https://picasaweb.google.com/lh/photo/efr6sC6dDFXU9Ho3groOu9MTjNZETYmyPJy0liipFm0?feat=e mbedwebsite"><img src="https://lh6.googleusercontent.com/-uqGEdKFh9zk/UKw_DUzQFrI/AAAAAAAAA3g/qxN4o3-G4-U/s640/DSC_8444.JPG" height="425" width="640" /></a></td></tr><tr><td style="font-family:arial,sans-serif; font-size:11px; text-align:right">From <a href="https://picasaweb.google.com/107685368595078804853/1106Porsche911OriginalState?authuser=0&feat=embedw ebsite">11 06 Porsche 911 original state</a></td></tr></table>

<table style="width:auto;"><tr><td><a href="https://picasaweb.google.com/lh/photo/tJaiL6d3yiZgirMZa7ZQQNMTjNZETYmyPJy0liipFm0?feat=e mbedwebsite"><img src="https://lh6.googleusercontent.com/-ZzwHsHCpZZU/UKw_FtJ7c_I/AAAAAAAAA3o/4KWcBWzsp-g/s640/DSC_8463.JPG" height="428" width="640" /></a></td></tr><tr><td style="font-family:arial,sans-serif; font-size:11px; text-align:right">From <a href="https://picasaweb.google.com/107685368595078804853/1106Porsche911OriginalState?authuser=0&feat=embedw ebsite">11 06 Porsche 911 original state</a></td></tr></table>

Notice in that last photo that there is a connection from the brake reservoir to the vent. I guess it acts as an overflow relief if you overfill the brake reservoir?

Thanks Von! I always wondered why the overflow from the brake reservoir never went anywhere in my car. When I first bled the brakes I ended up overfilling the reservoir and ended up having to respray a bunch of the trunk. Routing it through the fuel vent hose seems like a great way to deal with it. Based on your picture it looks like there was a significant difference between the tank vent system for 68 and 69. I will try to track down the correct vent canister for 69 but if it proves to be too expensive I will use your pictures to fabricate a pre 69 vent system. I think I can get the measurements from the pictures you posted by using the brake fluid reservoir as a reference as I can measure that on my car.

Hi Larry,

I am glad that you like the thread! I have been following yours and the irish green looks amazing. So good to see another 69 being saved:) Putting the car back together after paint is wonderful and it had been by far the most rewarding part of the project. If you have any questions about reassembly feel free to shoot me a PM.

Thanks David,

I am going to try and get my hands on one of the vent containers correct for 69 and I have a few leads from a WTB add I posted yesterday. In terms of the gas smell there were several days before I took the Rat apart where I could see fumes exiting the vent system I had. This occured mostly on hot sunny days, which are quite rare in FL ;-). If I can get my hands on a vent container for under the cowl for a reasonable price I will plumb up the exact system for 69 and test it out. If I still have a ton of fumes I can always put a cannister in "as an upgrade" afterward. if the container is too expensive I will replicate the pre 69 system that Von posted pictures of. Thanks for all of the advice and for emailing me the pictures of the correct layout.

Cheers,
Kristoph

Thanks Randy! I am planning on using the correct setup from 69 and giving it a test run. If there are a ton of vapors still coming from the venting system I might update with a cannister. In terms of gas smell I think Obi Wan had it right talking about the float bowls on the carbs being the major culprit. In terms of the "benzene" in the fuel vapor I know that it can be dangerous but I am not sure it applies to normal use of a correctly set up older vehicle. My parents (and everybody elses parents) drove cars with carbs and we are all still here to talk about it ;)

Day 81: Today I was able to make a small amount of progress with the help of my Porsche Padawan. Noah was able to help me get the final fender bolts installed using his small Padawan finger power. We also "fixed" the liscense plate lights by putting the plexiglass on the inside.

Noah was able to use his small fingers to start the bolt which allowed me to tighten it with a U joint. I made sure to tape off all of the edges so the paint would not get damaged
http://forums.pelicanparts.com/uploa...1353468297.jpg

The difficult bolt was the furthest one to the left in the picture below
http://forums.pelicanparts.com/uploa...1353468378.jpg

Plexiglass installed on the inside for the liscense plate lights
http://forums.pelicanparts.com/uploa...1353468441.jpg