Skip to main content

Hi everyone

I have owned my new 356 speedster from VMC (bought through Roy at Cloud 9 Classics) for about 2.5 months now and as the weather gets better I'm taking the car out a lot more.  I now have over 130 miles on the odometer!  Yay.  Big shout out to Greg and Anna at VMC as they were fantastic to work with when the car was being built and their after sales support was excellent too as I has a few things I needed taken care of after I got the car.   Buying from Roy was a great experience too and he made the whole process very straight forward.

OK, now onto the topic of this post...

One of the things that got my wife all negative was the constant smell of gasoline in the garage and every time you opened the door from the house to the garage, the gas fumes came into the house.  So this led me to read up on the gas fume topic in the various posts on this forum and I saw that a lot of other members had the same experience too.  The answers were great, but they didn't help my wife out as "this is the way VW carbs are... and it's part of the 356 Speedster owner experience".

The carbs and the exhaust pipes were the source of the gasoline/oil smell coming from my vehicle, so this was the area for innovation I concentrated on.  After trying various ways to limit the evaporation from the carbs, I'm happy to report that I came up with carb and exhaust tip "booties" for my little widebody Speedster - and it has dramatically reduced the gasoline smell down to almost nothing.

I tried different materials to make the booties and used a thin 2mil rubber sheet first, but that was too hard to put on and take off as it didn't have enough stretch in it.  The rubber was grippy too which didn't help at all when trying to slip them over the air filters.

Next, I upgraded the idea to use Polyurethane (PU) coated fabric and that did the trick as it had enough stretch in the material to allow for easy installation and removal of the booties.  The PUC fabric also has a polyester fabric on the outside which made it pretty slippery and this helps with the booties gliding on and off the metal parts a breeze.  I doubled up the fabric and used a sewing machine to stitch everything up - with a zigzag stitch to allow the fabric to stretch and making the booties about 1/2" smaller than the circumference needed.

This allowed enough stretch in the fabric to make a good seal around the carb's air filters, and for the exhaust pipes, I went 3/8" smaller than the exhaust tip's circumference.

Here's a few pictures of the booties installed on the carbs and the exhaust tips.

After installing these and airing out the garage for 5 minutes, I closed the garage doors and left it overnight to see if the gas smell will accumulate again.  This morning, opening the door from the house to the garage resulted in a dramatic improvement as there was only a small hint of gas fumes.  This may be from the stuff in the garage that absorbed the fumes for 2.5 months so we'll see if it all goes away in a few weeks with the booties installed.

For those still dealing with gas fumes, you may want to give this a try.  I bought the PUC fabric from a local fabric store for about $6 (1/2 yard) and it took me 1.5 hours to make them with the wife's sewing machine.

Just make sure you install them AFTER THE CAR HAS COMPLETELY COOLED DOWN so there's no risk of condensation or anything weird.  And remember to take them off before firing the car up for the next run!

Happy Hooning!



Images (3)
  • Booties over dual Solex carbs
  • Bootie eliminating gas smell
  • Booties over exhaust tips
Original Post

Replies sorted oldest to newest

I'd install Wolfgang's fuel shut off. At the end of every drive, pull 2/3 of the way into the garage. Set the parking brake, put the car in neutral, get out and shut the fuel off. Leave the car idling until the floatbowls run dry and the car dies.

Release the parking brake, push the car into the garage. You're done. It won't smell.

Does the lawnmower freak her out as well?

Hmmm ... not really a fan of this solution to an innate problem.  But ya gotta do what ya gotta do, 'cause that's what the lady says.  Another item to check is the gas tank vent, assuming you might have one.  Many cars are equipped with a one-way vapor gizzie that allows air to enter the tank as the gas is consumed but will not allow tank vapors to go the other way.  You might check about this.  This breathing operation can be achieved with just a hose running out the top of the tank, and this could also allow gas fumes to pass out absent the one way valve.  Side note: if you have the one way valve and store a cold car (or it gets cold while stored) with a not very full gas tank, and the temperature then increases a lot (say after a cold winter in the garage and then the weather warms notably) the captured vapor in the tank can generate enough pressure to overcome the fuel pump and the float valves in the carbs and gas will flood the carbs and drain down into the cylinders with intake valves open, pass the rings and end up in the crank case. There is nothing really very good about this.  If one checks one's oil regularly before firing up, this might be detected.  If not, excessive crank case pressure will begin pushing the diluted gas and oil mixture back into the cylinders, past the rings, and a great cloud of smoke will ensue, suggesting that you have just completely blown your engine, without the first clue why.  I've said enough, pls don't ask any embarrassing questions.

The immediate fix: drain out all the oil/gas and put in new oil and filter. Duh . . .

The proper future policy: store the car for the winter with a nearly full tank and/or remove the one way valve. Alternatively, move to Hawaii, SoCali, AZ or FL and don't think about this again.

@Stan Galat posted:

I'd install Wolfgang's fuel shut off. At the end of every drive, pull 2/3 of the way into the garage. Set the parking brake, put the car in neutral, get out and shut the fuel off. Leave the car idling until the floatbowls run dry and the car dies.

Release the parking brake, push the car into the garage. You're done. It won't smell.

Does the lawnmower freak her out as well?

I completely agree with what Stan is saying here, but this car has an electric fuel pump. Wouldn't it be easier to just find the fuel pump wire, and add a switch under the dash and a wire? You know, an electric shut-off?

And Stan, thanks for taking care of the El Frazoo comment, so I didn't have to.

And take heed of El Frazoo's comment about fuel pressure in the tank for cold/hot conditions. That is a good catch for the future.

Last edited by DannyP

Thanks for the great tips guys.  As part of my gas fume investigation journey, I knocked out a few of the items suggested.

1. Inspected the one-way valve on the gas tank's filler neck and it was installed and running properly.  Also, there is no gas smell at the bottom of the overflow hose that's by the passenger side front wheel well.

2. Inspected all the fuel line hoses, fuel filter, and hose clamps from the carbs all the way back to the tank.  Found nothing and everything was tight.  The fuel line's braided cloth was dry and no smell of gas.

3. I inspected the oil after each run as part of the investigation and the oil level remained constant.  Also, after changing the oil out and running the car on several outings, there is no gas smell in the oil.  So I don't think the carb needle/float is stuck.  I also took the air filter off and inspected the carb and didn't find any excessive wetness.

4. As @DannyP mentioned, my new VMC is outfitted with an electronic fuel pump.  Do you think it's still wise to install at fuel shutoff valve (either manual or a switch to the electric pump)?

I'll definitely take note of @El Frazoo advice on keeping the tank full if stored for a while with varying temperatures.  I'm in the middle of building out my dream garage and I'll have HVAC in there to ensure I don't see too much temp swings or humidity.  In TX, we can get super hot for weeks at a time and the humidity can be a real drag on trying to keep a car pristine.

Thanks for everything and if you think of anything else, let me know.  Carb booties seem to be helping for now.


I'm dropping a link to a "vapor trapper" for gas tank vents. The one I've linked to is crazy expensive, but it gets the idea across. A DIY type could easily make one for very little and plumb it into the vent line, maybe even mount it in the wheel well.

I think that this kind of thing, coupled with the ideas above, would make it pretty much stink free.

Anyway, here's a link to: VAPOR TRAPPER

@WOLFGANG posted:

Yup I remember those carbon canisters used back in the early '70's.  Are they still on cars?  I hear that's why they say not to top off gas as you'll contaminate the charcoal???

My Smart has one. Pisses me off. It’s the last emission parameter that resets after I clear my codes. Sometimes it takes ~100 miles and 2-3 run cycles to gather enough info.
(I have a CEL due to “rich running at idle” because I’m too lazy to pull my MAF out and clean it. I run a tank of 44k every summer and clear my codes before my emissions test and it stays off for 3-4 months)


@pkdfw , I admire your resourcefulness, and the carb cozies are cute, but here's another opinion (and we're all entitled to an opinion, right?).

I think the best way to deal with trapped gasoline vapor is to vent it as quickly as possible into a wide, open space, not confine it in a closed space with other flammable materials. I may be overly cautious about this, but I don't run with scissors, either.

I've had my Speedy just over ten years now, and it has always done this (more so in hot weather, BTW). What I do is open the engine deck lid and leave the garage door open for about an hour after parking the car. By then, the carbs are no longer 'outgassing', so I button things up and close the garage door. I think Stan's solution (or maybe Danny's version of Stan's solution) is the best way to go — if you have an electric fuel pump — but my fuel pump is mechanical, so I do what I do.

I've noticed that the carbs don't give off fumes when the car is running or right after I shut it down. The fumes start about 10-15 minutes after shutdown and last for about an hour. I think what is happening is a result of the engine (the carbs, actually) getting hotter after shutdown than while the engine (and the fan) are running. This makes gas in the carbs percolate, rise to the top of the carbs, and overflow down the outside of the carb bodies (as vapor). You may start to notice oily dirt accumulating on the outside of the carbs over time for this reason.

Anyway, that's my take on this and the simple solution I've found that seems to work. If you're getting fumes even when the car is parked for long periods, maybe you've got a different issue than I do. But, again, if you can, emptying the float bowls of gas completely before putting the car away is good advice for a number of reasons.


Last edited by Sacto Mitch
@Sacto Mitch posted:

... The fumes start about 10-15 minutes after shutdown and last for about an hour. I think what is happening is a result of the engine (the carbs, actually) getting hotter after shutdown than while the engine (and the fan) are running.


When the engine is running, the fuel is moving through the bowls -- getting sucked up the jets and burned in the engine to be replaced with new, cooler fuel. When the engine is shut off, the heat from the heads rises through the manifolds, heat-soaks the carbs, and boils the stationary fuel in the carb float bowls.

@Sacto Mitch posted:

... emptying the float bowls of gas completely before putting the car away is good advice for a number of reasons.

Let's assume that the carbs never off-gassed, that the OP's wife wasn't looking for a reason to hate the car, and that the garage smelling like a garage wasn't a problem for anybody.

That would pretty accurately describe my situation, but I'm still advocating running the floats dry.

If a guy sticks around here long enough, he'll get to go through the irregular but predictable rite of passage that is our official SOC sitewide pouty-party regarding ethanol in fuels (we're overdue guys -- get on it!). You see, like it or not (and almost nobody does), our fuel is about 10% corn-squeezins. The ethanol in your gas is corrosive and hygroscopic. Left sitting in your floats, it'll start eating every plastic thing in the carbs and begin going after the metal as well. It will draw in moisture from the ambient (the humidity in the air), condense at the bottom of your bowls, and form a jelly that will plug up every jet in your carbs. If you empty the bowls, it can't/won't do that.

Both "gasoline" (a combination of petroleum distillates) and ethanol have a lower boiling point than you'd think: gas boils between 100 and 400 deg F, and ethanol at 173 deg F. Your engine is hotter than that when you pull in, and the fuel in the bowls will start boiling as soon as the gas stops flowing. Kardons are worse about this than Webers or Dellortos, but any carbureted engine (I keep coming back to it, but the lawnmower included) will do it.

Shutting down the electric pump will empty the bowls, but depending on how full the fuel tank is (and especially if it's full), the level of the fuel in the system may be high enough to allow migration to the bowls by simple gravity.

I'm a belt and suspenders guy. I'd put the valve in the system and a switch on the pump -- not because of the tender sensibilities of the woman in my life, but because taking care of equipment is a high virtue in my estimation, and I have no more valuable piece of equipment than my clown car.

A guy will do what he wants to do, and the OP clearly likes his solution. I'm not trying to dissuade anybody from anything, as I doubt there's any bad thing that will happen from shrink-wrapping the carbs and exhaust -- I'm just saying there are other, even better reasons to run your bowls dry.

Do it for your car. Do if for "the children". Do it for America.

Last edited by Stan Galat

@Stan Galat and @Sacto Mitch , you guys bring up good points.  On my Speedster, it does what Mitch said and the gas vap smell comes about 15 - 20 min after the car is parked back in the garage.  For my car, the gas will vap for a long time, like several days for some reason.

Do you think the float or pin is stuck open in the carb?

Stan's idea of draining the carbs due to the ethanol may be a good reason for adding the valve and switch for the electronic fuel pump.   Does anyone know of there's a fuse for the fuel pump in the VMC?



@Stan Galat posted:

I doubt it, but Kadrons have notoriously terrible needle valves, so it's possible that you have one weeping. If you do what I'm advocating, it will never be a problem.

Agreed. I fear that Kadron/Solex float valves are given a bad rap like Weber IDFs.

You see, Solexes like a measly 1.5 pounds of fuel pressure. Any more than that and they will let the fuel blow past.

And NOBODY actually checks the pressure. Except me, maybe. I did Solex 35 PDSIT duals on an 1835 a while back, using the mechanical fuel pump. It took 7 gaskets under the fuel pump to get the pressure down to 1.75 psi. Yeah, 7 gaskets!

Electric pumps are usually 3 to 3.5 psi. Is that enough to make them weep? I don't know for sure, but I suspect.

I echo all Stan's thought on ethanol blended fuels. The stuff is just bad and caustic and there is no reason other than to line corporate pockets.

I would also check to ensure you don't have a gas hot water heater or gas furnace in your garage.  If the car's gas fumes get strong enough, either could spark off an explosion/fire.  A small electric fan might be good for dispursing fumes - Place it on the floor and leave the garage door open a few inches after parking.  Our FL condo doesn't allow storage of gas or propane containers in our detached garages.

@WOLFGANG posted:

I would also check to ensure you don't have a gas hot water heater or gas furnace in your garage.  If the car's gas fumes get strong enough, either could spark off an explosion/fire.

While I guess this is hypothetically possible, I will eat the chair I'm sitting on if anybody can produce solid evidence of a car (or lawn mower) without a dripping gas leak "off-gassing" and blowing up a building.

Heck, forget the chair, I'll eat the computer I'm typing on.

@WOLFGANG posted:

Our FL condo doesn't allow storage of gas or propane containers in our detached garages.

Remember when I was ranting about HOAs and planning and zoning, and said I could never live in FL? This is exhibit "A".

Last edited by Stan Galat

I just had a new oil furnace installed last week (no gas on the property).

The crusty installer (owner of a very established company) told me he considered my walk-in basement (from the garage) .... a garage .... since I had my motorcycle stored in there and any drip might blow the house up. I asked him what he thought of the 900 liter tank of diesel sitting 10 feet away that feeds the furnace  and he shut right up 

Might have missed it, but with the idea to shut off the fuel with engine running and thus drain the float chambers:  is this a "every single cycle" sort of thing, or just prudence when storing the car for a while?  sounds like a good idea, and it is what I do with my lawn tractor for winter and snow blower for summer, but never thought of doing same for the Speedster.  Instead, I Use a bottle of SeaFoam in the tank.  So, put a Fuel cut off valve in the fuel supply? ...  Not hard to do, sounds pretty good.  I have a new project . . .

And its not so much the "cool" liquid fuel flowing through the carbs when operating that keeps them cool-ish, but rather the heat of vaporization of the vaporizing gas in the air in the  venturies.  And when all that stops when the engine is turned off, and the engine heat soaks up through the highly heat conductive aluminum manifolds, the gas fumes will be most notable, espy with Webers and others that have open float chambers.  Pop the lid in the back, keep the garage door open for a bit.  That should do it by and large.   I hear that they make thicker manifold gaskets that act as heat insulators to minimize the heat back up thing.  I tried those once and due to a combination of other things, ended up taking them out.  Full disclosure: a little gas fume in the garage is not an issue for me, and there is no OP around most of the time to take any notice.

@Stan Galat posted:

Kadrons may have a bad rap, but IMHO it's earned. They're agricultural-grade carbs and unless things have changed in the last 15 years, the needle valves have no rubber on them. They rely (or relied, anyhow) on a simple brass on brass seal to stop the flow.

I don't care if it's 1.5 psi or .15 psi -- that's a bad way to seal anything.

Agreed. I'd like to know the fuel pressure on Phil's carbs.


I have to hand it to you, that is a very clever, inexpensive and effective solution to a smelly problem that has come up on here numerous times.  Your wife is not the only one who objects to the gasoline smell.  Some of our wives are a bit more tolerant than others, but I think they all notice it.

I also support the idea of a separate switch to turn the fuel pump off as you pull into the driveway (or just before, if you choose) and thereby drain the float bowls while the engine runs-out over a couple of minutes.  This should eliminate a lot of the smell, especially over subsequent days and give the added plus of helping to eliminate varnish from the fuel clogging the carb passages over time.  Doing that is a bit easier than adding a fuel cut-off valve somewhere.

Another added bonus is if you hide that switch somewhere more-or-less out of sight, it doubles as a theft deterrent.  No fuel, no go!

I would also try to find out what the fuel pressure is going to your Kadrons - As others have mentioned, it might be a little high and forcing past the float valves but that would be a "nice to find out" item after a while.

In the end, though, it's a simple thing to put the little socks on in what, a minute?  And they seem pretty effective so Kudos and a Tip 'o the Hat to you, sir!



Images (1)
  • hatlo-hat-tip-300

Thanks Gordon.

BTW, what is the easiest way to find out what the pressure is going to the carbs?  When I get some time, I'll put the car up on a lift to see if I can find the wires going to the electronic fuel pump. 

I have a 2 post lift ordered and it's supposed to be installed in early April.  Now I have my first project!

Good work, I personally also deal with this issue as it seems to annoy me more than my wife, but its far far less prevalent on the tiny solex's on the speedsters.

On my 750 holley double pumper however, its a much bigger issue, I turn off the electric fuel pump, and proceed to pump the throttle until its completely dry and the bowls are empty as well as any residual in the accel pump circuits. This drastically reduces the odor in the garage after shut off. I also run fans in the garage on smart switches for a period of time before closing the garage.

You may also want to get your carb tuned. A overly rich carb will also have more residual odors in the exhaust.

I would consider the following -

1. get an switch installed for fuel pump. run it dry before pulling it into the garage. as noted above, heat soak will evap your bowls and cause fumes.

2. understand how your jetting is performing, go get it dyno's with an AFR and tune it as needed.

@pkdfw wrote: "BTW, what is the easiest way to find out what the pressure is going to the carbs? "

If you have an electric fuel pump it should be on a small shelf in front of the passenger's feet beyond the bulkhead.  There may or may not be a filter on the gas tank side of the pump.  The fuel hose runs from the pump along through the center tunnel to the engine and usually appears in the engine compartment on the driver's side somewhere.  Once in the compartment it goes to one of the carburetors and then "T"s off to the other carb.  You have to place a small-ish fuel gauge between where the hose enters the compartment and that first "T".

You want a gauge that shows 0 - 15 PSI  
This is a good example:

You can mount it temporarily to get a reading and/or adjust things, or you can make it a permanent installation  - It's up to you.

Oh, and if you have a mechanical fuel pump (I don't know what you've got) it is mounted on the engine to the right of the distributor and left of the alternator stand.

Several of us on here can guide you through checking fuel pressure and/or adjusting it once you know what's going on.

@WNGD posted:

I live in the woods on the edge of town.....a no Karen zone.....we have our own flag and anthem and yes....a bridge to get onto the property.

I know you do, 'twas a joke. I'm a jolly jokester.

I've seen the pictures of your setup you've posted over the years, and I can't imagine you subjecting yourself to any HOA/Preservation District nonsense. That, and no HOA would ever stand for an oil burner -- it would offend Karen (the HOA president)'s tender sensibilities.

... now about that mailbox...

Last edited by Stan Galat

Add Reply

Post Content
Link copied to your clipboard.