No expansion tank and no charcoal canister, Does this mean gas fumes entering the cabin? Options

[MM1]

My latest carbureted project has no expansion tank or charcoal canister .

Does this necessarily mean that I will smell fumes entering the cabin while sitting at a stoplight or driving ?

[Shivers]

I never noticed it, but I rarely have the top on. Some of the others have said in previous posts that it did help a lot with their carbed cars.

[wonkipop]

My latest carbureted project has no expansion tank or charcoal canister .

Does this necessarily mean that I will smell fumes entering the cabin while sitting at a stoplight or driving ?

neither did euro spec 914s.
i've seen a very early euro spec 914/6 here, had no expansion tank and no cannister.
seen a 73 euro spec 914 2.0. it had the expansion tank, but not the cannister.

i might be wrong but i think they literally ran the breather tube straight down the side of the tank and left it open in that slot across the front end underneath.
something like that. someone else will know for sure. but they did not have the vent hose hanging about in the front trunk area.

[Superhawk996]

My latest carbureted project has no expansion tank or charcoal canister .

Does this necessarily mean that I will smell fumes entering the cabin while sitting at a stoplight or driving ?

No

You may smell it after sitting in a garage.

[barefoot]

I connected a small diameter plastic tube to the vent fitting at the fuel filler and routed it down under the car. i do not smell gas even sitting for long periods in the garage.

[FL000]

Just another data point, but I had the gas smell in mine before I added them back in. It was mainly when I had a very full tank and around the corners IIRC.

[Steve]

I think it all depends on your setup. When I had carbs with one feed line, I didn’t notice it. After installing the 3.2 with injection and return line, it was really horrible. I installed a charcoal canister in front of the battery tray, stock expansion chamber on tank and no more vapors.

[JamesM]

Just another data point, but I had the gas smell in mine before I added them back in. It was mainly when I had a very full tank and around the corners IIRC.

(IMG:style_emoticons/default/agree.gif) ^that

Carbed or not, if there is no line/broken line from the small port on the filler neck, take a hard left with enough gas in the tank and you will for sure smell it, if you haven't been already.

[MM1]

Great info as always . . .thank you, all!

[MM1]

My latest carbureted project has no expansion tank or charcoal canister .

Does this necessarily mean that I will smell fumes entering the cabin while sitting at a stoplight or driving ?

neither did euro spec 914s.
i've seen a very early euro spec 914/6 here, had no expansion tank and no cannister.
seen a 73 euro spec 914 2.0. it had the expansion tank, but not the cannister.

i might be wrong but i think they literally ran the breather tube straight down the side of the tank and left it open in that slot across the front end underneath.
something like that. someone else will know for sure. but they did not have the vent hose hanging about in the front trunk area.

Thank you for the OEM facts, @wonkipop !

[wonkipop]

My latest carbureted project has no expansion tank or charcoal canister .

Does this necessarily mean that I will smell fumes entering the cabin while sitting at a stoplight or driving ?

neither did euro spec 914s.
i've seen a very early euro spec 914/6 here, had no expansion tank and no cannister.
seen a 73 euro spec 914 2.0. it had the expansion tank, but not the cannister.

i might be wrong but i think they literally ran the breather tube straight down the side of the tank and left it open in that slot across the front end underneath.
something like that. someone else will know for sure. but they did not have the vent hose hanging about in the front trunk area.

Thank you for the OEM facts, @wonkipop !

MM1 - i am fairly sure the expansion tank is a fuel injection thing.
i had an old type 3 squareback with twin carbs. no expansion tank. vented through a hose to u/s side of car. i had a mate who owned a EFI fastback (rare fuel injection in aus). it had an expansion tank. perhaps something to do with fuel circulating constantly at high volume and rising slightly or significantly in temp and needing the vapor/volume expansion area.

probably explains why the 6 i saw did not have one. carbs.

does not explain why USA 6s had the extra tank, but maybe that was just beneficial to the cannister sealed system.

but does explain probably why the 73 2.0 i saw and knew well back in the 90s did have the tank. it was EFI.

that 73 2.0 never stank of fuel as i recall.
but the 6 did. might have had something to do with those massive carbs sitting right there venting? the same guy had a late 60s 911 and it stank to high heaven too. (IMG:style_emoticons/default/smile.gif)

[MM1]

That makes sense.

I once had a Datsun 260 Z (best sounding car I’ve ever owned) with a stock carb set up and it smelled like fuel all the time. It was unbearable (at least it was to my then girlfriend) until I managed to finally get a used shifter boot (the only guy in New Orleans at the time that had a shop that worked on Z’s took pity on me and gave it to me, God bless him).

My friend”s 1975 Dino 308GT4 also smells like fuel a lot even though all the fuel is stored behind the driver. I think it is akin to airflow returning to the cockpit from the back of a convertible that has no windscreen to minimize or prevent such flow. I have smelled fuel in that car even on the freeway at California Highway speeds - not all the time, but enough times to notice.

[Robarabian]

Just another data point, but I had the gas smell in mine before I added them back in. It was mainly when I had a very full tank and around the corners IIRC.

Josh,

@mm1 is running a V-8 like you. Maybe you could post a photo of your setup, it may help Marcus figure out a path. You car is pretty nicely set up and it would be a good goal for his car to mirror it.

[Superhawk996]

That makes sense.

I once had a Datsun 260 Z (best sounding car I’ve ever owned) with a stock carb set up and it smelled like fuel all the time. It was unbearable (at least it was to my then girlfriend) until I managed to finally get a used shifter boot (the only guy in New Orleans at the time that had a shop that worked on Z’s took pity on me and gave it to me, God bless him).

My friend”s 1975 Dino 308GT4 also smells like fuel a lot even though all the fuel is stored behind the driver. I think it is akin to airflow returning to the cockpit from the back of a convertible that has no windscreen to minimize or prevent such flow. I have smelled fuel in that car even on the freeway at California Highway speeds - not all the time, but enough times to notice.

Don't take this the wrong way. It seems to me based on OP and this post above that you are highly sensitive to the smell of gasoline. That's OK.

For me, the smell of oil and gasoline is the smell of 50 year old machinery. I love it. (IMG:style_emoticons/default/wub.gif) Likewise don't take that the wrong way. I despise oil leaks and I would never accept fuel sloshing over out the tank vent into the Funk and filling the cabin with fumes.

The moral of the story, it seems that you've probably become accustomed to modern vehicles with complex evaporative emissions recovery systems that emanate nearly zero gasoline vapors.

You'll never get zero gas smell from carbs. The simple fact is that the fuel bowl is vented to atmosphere and you'll get a whiff of gasoline, some way, somehow. Especially if you're sensitive to it.

Reminds me of an old favorite ZZ Top slow blues song:

I done ran into my baby
And finally found my old blue jean
I done ran into my baby
And finally found my old blue jean
Well, I could tell that they was mine
From the oil and the gasoline

If I ever get back my blue jean
Lord, how happy could one man be
If I ever get back my blue jean
Lord, how happy could one man be
'Cause if I get back those blue jeans
You know, my baby be bringin' 'em home to me


https://www.youtube.com/watch?v=uwn4CD9dfAI

[MM1]

Good post - how often do we see lyrics here?

I definitely don’t like the smell of gasoline or any fuel vapor in the cabin. I do however love the smell of a 914 interior which obviously is oil mist (and possibly some fuel vapor) from 50 years of driving-lol.

The proposition about being used to tightly controlled fuel injection systems on modern cars is entirely applicable for most people in this world today. I would say that is not the case here, though, since I grew up (and did not drive a fuel injected car until I bought an Acura Integra in 1987 ) long before a few injection was common,l. None of those carbureted cars that I rode in and drove had ever smelled like fuel in the cabin - at least not enough that I ever noticed. My 1972 GMC Jimmy which I have owned for 20 years) obviously is carbureted and I have never smelled fuel in the cabin. Also, as most if us, I have ridden in many cars from multiple generations that were carbureted and the only ones that ever smelled like fuel in the cabin (to me) were the 260 Z (my friend also had one and he had the same issue), and that Dino 308 GT4 - although my friend’s Z and the Dino could possibly have had a loose hose or something, I believe the Z’s very possibly had a fuel smell because of fuel slosh. Still I was a bit surprised by the Dino since the engine and fuel system are completely behind the driver. A more modern knowledge of aerodynamics can possibly explain this is as normal for an early mid-engined (little if any wind tunnel “fuel smell” tested) car however.

As for the rides and drives I’ve had a 914’s, I don’t recall smelling fuel in the cabin either. When I recently acquired this V8 project l, the fuel filler was not on the tank, and there are brackets for an expansion tank and a charcoal caster. They did not, however, come with the car. Having worked for the automotive industry for a few decades (should’ve stayed on the medical school path or even better become an investment banker (IMG:style_emoticons/default/headbang.gif) ) , even though I think we all can be very frustrated with engineers on numerous occasions, these large companies do have the money to develop solutions that are generally successful. For example it seems that most people here believe that the OEM sway bars front and rear are the ideal set up for a street 914-4 despite the fact that many have installed larger sway bars over the years.

I suspect Porsche got the fuel system right mostly from the start (apparently except for the fuel pump placement in regards to vapor lock). That’s why I started this post - before I receive and install this new tank I just wanted to know if I should get the expansion tank and charcoal canister and return the system to stock in order to avoid any potential fumes even though that might not be common in most vehicles.

[Superhawk996]

I just wanted to know if I should get the expansion tank and charcoal canister and return the system to stock in order to avoid any potential fumes even though that might not be common in most vehicles.

The main issue is that with a V8 and Carb, there is no going back to "stock".

There is no magic in the expansion tank or the charcoal canister. The stock setup pushes the stored vapors out of the canister, using the engine fan to provide pressure and dumps them into the air cleaner box where they can be sucked in with intake air.

With a carburated V8, you're going to be on your own to come up with an arrangement to dump vapor into the air cleaner.

I'm sort of baffled by this: When I recently acquired this V8 project l, the fuel filler was not on the tank". Where is it? What sort of mod's have been done?

[wonkipop]

I just wanted to know if I should get the expansion tank and charcoal canister and return the system to stock in order to avoid any potential fumes even though that might not be common in most vehicles.

The main issue is that with a V8 and Carb, there is no going back to "stock".

There is no magic in the expansion tank or the charcoal canister. The stock setup pushes the stored vapors out of the canister, using the engine fan to provide pressure and dumps them into the air cleaner box where they can be sucked in with intake air.

With a carburated V8, you're going to be on your own to come up with an arrangement to dump vapor into the air cleaner.

I'm sort of baffled by this: When I recently acquired this V8 project l, the fuel filler was not on the tank". Where is it? What sort of mod's have been done?

thats right, if MM1 wanted to do it he would have to find a way to dump into the air cleaner and.....
the systems for charcoal can etc were a little different on those american water cooled V8s etc. i think they used an actual valve and just let induction draw the air through.
then air inlet valve closed at switch off. perhaps better to adopt a US domestic system of either the era or now and install?

could be difficult to rig up VW or porsche style system. no air cooling fan to bleed air off to oxygenate the charcoal. which is really what the fan line does. it lets the induction suck the air in the first place through that line without creating a vacuum in the can and the fan assists to sort of "boost" it or flood it. but mostly its really the induction draw that is pulling it through into the engine? (IMG:style_emoticons/default/beerchug.gif)

EDIT
the vw porsche system is pretty lame when you look at it closely.
its open to the atmosphere via the fan bleed.
and it can release fumes through the aircleaner snorkel.
(all cars had the second problem).
but VW were open at two ends.
basically they were making the charcoal be the valve.
which is why they stink so bad when they get fully saturated.
i've pulled the fan hose off and it stunk every bit as bad as the air cleaner hose.
a bit of freeway driving fixed that up but.

[MM1]

I love these lessons about the charcoal canister system, thank you, kind Sirs!

Once I am driving this V8 conversion, I’ll know if gas fumes are entering the cabin. If so, I’ll further investigate solutions.

When I get this new fuel tank, I’m going to reassemble it with no expansion tank and charcoal canister based upon the facts that the car did not come with either of these parts nor would they work, apparently, as engineered with a V8.

The fuel filler (sans the required bolts) was in the (rear) trunk along with a few other bits when I purchased the car. Yes, sage friends, we covered the filler hole in the tank before transporting-lol.

[Biggles]

I think it all depends on your setup. When I had carbs with one feed line, I didn’t notice it. After installing the 3.2 with injection and return line, it was really horrible. I installed a charcoal canister in front of the battery tray, stock expansion chamber on tank and no more vapors.

Thats interesting Steve.
I have the same 3.2 on injection and after a while it stinks but i dont have the expansion tank and charcoal filter as i thought it was more weight i didnt need !

The seals to my tank are new and pipes are all ok so where could it be coming from? Where do you suspect it was coming from in your car?

[Steve]

I think it all depends on your setup. When I had carbs with one feed line, I didn’t notice it. After installing the 3.2 with injection and return line, it was really horrible. I installed a charcoal canister in front of the battery tray, stock expansion chamber on tank and no more vapors.

Thats interesting Steve.
I have the same 3.2 on injection and after a while it stinks but i dont have the expansion tank and charcoal filter as i thought it was more weight i didnt need !

The seals to my tank are new and pipes are all ok so where could it be coming from? Where do you suspect it was coming from in your car?

If you don’t have an expansion tank and charcoal canister, best practice is to run the tank vent under the car. The vapors still managed to get inside the car and in the garage which annoyed my wife and kids. No more vapors after installing the expansion tank and charcoal canister. With these devices installed it is a closed system.