# Simplified Vapor Fuel Tank



## cfellows

I came up with a simpler Air mixer for a Fuel Vapor Fuel Tank. Here is a Picture.







The vapor fuel tank draws air into the tank through an air inlet. The air passes over the surface of the liquid fuel and draws fuel vapor through the outlet and to the engine. However, the pure vapor is too rich and needs to have additional air mixed in. 

In my version, the inlet tube going to the engine has a 1/8" wide slot cut into the side. A threaded collar fits over the tube, and by screwing and unscrewing the collar, the slot is more or less uncovered, allowing more or less air to be mixed with the fuel. This adjustment isn't particularly sensitive since the collar and tube OD are threaded at 1/4 - 28. 

I just installed this setup on my hit n miss engine and it works great. I used a small pimento jar for the tank and fitted the brass tubes to the jar lid. The engine starts first pull every time and continues to run as long as there is fuel. Pictures to follow later.

Chuck


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## Maryak

Chuck,

Very Nifty. :bow: :bow: I am thinking, (no don't worry :), about fuel for my hit and miss. Truth is I don't have a clue what it should be.

Gas - as in LPG. ???

Petrol - as in US gas - Octane level. ???

Coleman fuel - don't know what that is - Cetane Index ??? - imagine it's some kind of kerosene based lamp or stove fuel. ???

Any help would be greatly appreciated.

Best Regards
Bob


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## cfellows

Bob,

Coleman camp fuel is made from Naptha Petroleum. Very clean burning. I originally fired my engine with 87 octane gasoline. I had a standard fuel tank with a simple needle valve type carburetor, no butterfly. I was able to switch to Coleman fuel with no changes to the fuel tank or carburetor.

Recently I changed to the vapor fuel tank and no carburetor, just the simple air mixer in this post. It starts very easily and runs great.

Will upload a video later.

Chuck


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## cfellows

Here's a video of my Hit n Miss with the new, Vapor Fuel Tank attached. It's a pimento jar! The setup is as described and drawn further down this thread. It's also described in the video.

[ame=http://www.youtube.com/watch?v=wbqIfcjaIY8]http://www.youtube.com/watch?v=wbqIfcjaIY8[/ame]

Chuck


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## shred

Cool. This is with no carb at all?

You should put some red food coloring and pimentos in the jar... an a label that says "Caution, Extra Strong"


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## putputman

Chuck, you did it again. Such a simple solution to a nagging problem on most I.C. engines. Can't wait to try it out.
Thank you and count your karma.


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## CMS

Very clever, think I'll try this too.


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## Powder keg

Pretty cool Chuck!!! Does the efficiency go up? I imagine it would?


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## cfellows

Powder keg  said:
			
		

> Pretty cool Chuck!!! Does the efficiency go up? I imagine it would?



I don't really have any way of knowing. I do know, however, that there is no flooding. Also, I expect the droplets of fuel are much smaller than those produced by a tradional carb.

I also don't know about throttling. I assume you could put a butterfly between the engine and the air opening, but then I also expect you would have to tweak the air mixer if you moved the throttle.

Chuck


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## Jan Ridders

cfellows  said:
			
		

> I came up with a simpler Air mixer for a Fuel Vapor Fuel Tank. Here is a Picture.
> 
> 
> 
> 
> 
> 
> The vapor fuel tank draws air into the tank through an air inlet. The air passes over the surface of the liquid fuel and draws fuel vapor through the outlet and to the engine. However, the pure vapor is too rich and needs to have additional air mixed in.
> 
> In my version, the inlet tube going to the engine has a 1/8" wide slot cut into the side. A threaded collar fits over the tube, and by screwing and unscrewing the collar, the slot is more or less uncovered, allowing more or less air to be mixed with the fuel. This adjustment isn't particularly sensitive since the collar and tube OD are threaded at 1/4 - 28.
> 
> I just installed this setup on my hit n miss engine and it works great. I used a small pimento jar for the tank and fitted the brass tubes to the jar lid. The engine starts first pull every time and continues to run as long as there is fuel. Pictures to follow later.
> 
> Chuck


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## Bill Mc

Hi Chuck - Approximately what is the diameter of that jar because the exposed surface area would be very important as to how rich the vapor is as well. Part of that calculation would be as to what displacement the engine is also as to what the engines needs for proper combustion. - Billmc


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## zeeprogrammer

Just came across the pimento jar video. That's a great post. Thanks.


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## doc1955

Nice!
Pimento jar what a great idea I was thinking of adding a vapor fuel system to my IC motors and I like the jar idea.
 And Shred "extra strong" Rof} Rof} I like!

PS Nice running engine!


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## bearcar1

Somehow I missed this video for some reason but Chuck, that is a fantastic method and execution of air/fuel control. Well done! BRAVO! (it would be humorous to put some faux pimentos made from resin inside the glass jar) ;D Great running engine as well, what is it modeled after?

BC1
Jim


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## cfellows

Bill Mc  said:
			
		

> Hi Chuck - Approximately what is the diameter of that jar because the exposed surface area would be very important as to how rich the vapor is as well. Part of that calculation would be as to what displacement the engine is also as to what the engines needs for proper combustion. - Billmc



Bill, the pimento jar is about 2" diameter on the inside. The engine has a 1.0625" bore and 1.5" stroke. 

Thx...
Chuck


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## cfellows

The vapor fuel tank has been around for a long, long time. There are a number of old model engines on youtube which show a setup using a small jar similar to mine.

Jan Ridders resurrected the vapor fuel tank and, as far as I know, was the first to add an air mixer in the line. He has built several versions and the latest used a slotted disk that attached pretty close to the tank.

The only change I made was a simpler air mixer comprised of the threaded collar over a slotted opening in the fuel line. As some of you may have seen, I had also built a version of Jan Ridder's fuel tank from his plans for my Henry Ford engine. It was only after I tried out his tank design on my hit n miss engine that I decided to adapt the jar design and to try to simplify the air mixer.

So, thanks to Jan for his groundwork and for sparking the idea in the first place.

Chuck


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## eskimobob

Interesting - when I have seen these before, I had assumed that the tube which lets air in actually reached into the fuel in order to cause the air to bubble through the fuel - it seems that this is not necessary 8)


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## cfellows

eskimobob  said:
			
		

> Interesting - when I have seen these before, I had assumed that the tube which lets air in actually reached into the fuel in order to cause the air to bubble through the fuel - it seems that this is not necessary 8)



You're right, most of the earlier designs do show the inlet tube extending down into the fuel. But, as Ridders discovered, it doesn't have to. The rush of air into the container on the intake stroke generates quite a bit of turbulence in the liquid fuel. Also, if the engine fires back or the intake valve leaks, you don't get a geyser of fuel coming back out the air inlet pipe.

Chuck


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## eskimobob

cfellows  said:
			
		

> Also, if the engine fires back or the intake valve leaks, you don't get a geyser of fuel coming back out the air inlet pipe.



 I hadn't considered that but I would imagine that is very nasty - your method seems much safer


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## NickG

Good work Chuck, thanks for this. It will no doubt be very useful to me and a lot of other people.

Nick


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## Rustkolector

Chuck,
Do you have any ideas on how to size a vapor carb tank for larger model engines. I have about a 100cc slow speed model that I would like run on the vapor carb. I built one about 2x the size of Jan's, but it is woefully too small. Any ideas appreciated before I try a 5x. 
Jeff


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## putputman

Jeff, I don't know if this will help, but I used Chucks basic design and dimensions to build a vapor carb for one of my Red Wing engines. It started and run just like Chuck described. Took off on the first spin of the flywheel.

I couldn't find any pimento jars but I did find some small Ball fruit jars at Walmart. They were $4.00 for a package of 4 jars & lids. I actually like them better than the small jars as the fuel level is more constant while the engine runs. I found that with the Jan Ridder vapor tank, that as the level of the fuel dropped, I had to adjust the air intake to control the fuel mixer. With this larger & flatter jar, there is less effect from the fuel level.


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## cfellows

Nice one, Arv. By the way, you have probably already discovered that you don't need to mill a slot for the threaded air mixer valve. A simple hole,probably around 1/8" will do nicely.

Jeff, don't know much about the sizing. I calculated the displacement on my engine at about 21cc. There's a lot of factors involved. The surface area of the fuel in the tank, the air inlet size, and the size of the fuel line to the engine. 

Chuck


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## the engineer

great system i ran a 1700cc car on the same system a few years ago untill a backfire through the intake put some lovley burn marks in the paint but worked well enough for a single guy with no family to worry about 
things have changed a lot since those teen years ;D


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## cfellows

Here is my first attempt at a throttle control for the vapor carburetor. I haven't tried it out yet, but I do have it installed on my Henry Ford plumbinb parts engine.

It consists of a brass body, with a 1/8" thru hole, that threads into the intake side of the valve assembly. The fuel tube slips over the 3/16 nipple on the other end. There is a cross drilled hole that is threaded to accept an 8-32 socket head cap screw. Screwing the cap screw down closes off the 1/8" thru hole and restricts the amount of fuel/air mixture to the engine.

The fuel and air are mixed separately at the fuel tank side. I'm guessing the fuel / air mixture might need adjusting at different throttle settings, but we'll see.

By the way, these pictures were taken with my new Canon SD780. What a camera! These photos are reduced in size to about 30% of their original size (after cropping).
















Chuck


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## NickG

Looking good Chuck,

I've been waiting for somebody to try a throttle with the vapour carb. It will be interesting to see whether you can set the mixture at a happy medium that will allow you to open and close the throttle. I think you will, as you are not snapping the throttle open and shut but gradually adjusting it with the screw.

I had to put that camera into google to see if it was a DSLR. Fantastic pics, we bought a Panasonic Lumix TZ65 last summer as were advised it was one of the best digital compacts around. But the pictures you have taken there are better than I have managed so far.

Nick


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## mklotz

I'm very pleased that you're happy with the camera. I would hate to see you take my advice and be disappointed. It really is amazing how something with a lens that tiny can manage such good macro shots.


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## ariz

Chuck I missed this thread but I'm happy to have discovered it now

as you know I didn't succeed to run the scuderi engine, but when I'll have some time to give it a go, I'll try your solution on the vapour carb

I think that the problems of my engine were others (compression, leakages, etc.), but the simplified version of the vapour carb will help for sure

thanks for sharing :bow:


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## Brian Rupnow

Chuck---Thats one of the things I was thinking about with the vapour system.---A backfire!!! If your ignition timing wasn't "Right on" and it backfired through the intake valve and all thats between the cylinder and the fuel in the container is a nice open airway, whats the chances of it exploding the fuel container and drenching you in burning fuel.???


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## radfordc

The mixture in the fuel tank should be too rich to explode. You have to mix it with air to get the proper air/fuel ratio.


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## black85vette

Brian Rupnow  said:
			
		

> and it backfired through the intake valve



I am not 100% sure of this. On the Webster with the intake valve not using a cam to hold it open, but being held open only by the vacuum of the intake stroke, would that make a difference?


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## lee9966

Chuck,

I am very interested in your results. I just built a throttle body for use with a vapour carb, but a few other issues with this first engine of mine are postponing my trying it out. 

Lee


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## solver

Hopefully this isn't too much of an offtopic, just an idea of how to possibly reduce the damage caused by backfire:





If/when there is backfire, it hits first the spring loaded blue valve, closing it. Excess pressure then escapes through the red ball valve.

This is just a half-baked theory, as I have tested it only on small engine, which I never got to run decently with vapor carb.

Maybe on bigger engines, like Chuck's Ford plumbing engine, it could be more feasible to work with.


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## Longboy

black85vette  said:
			
		

> I am not 100% sure of this. On the Webster with the intake valve not using a cam to hold it open, but being held open only by the vacuum of the intake stroke, would that make a difference?


  I don't believe so for your reason, there is no mechanical means of keeping the intake open at time of backfire. The valve would be slammed to its seat if open and it then 'hiccups"!


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## cfellows

I agree that with a vacuum operated intake valve, back firing shouldn't cause a problem. I know that Jan Ridders usually incorporates a check valve in the fuel line to prevent anything going back into the tank.

Chuck


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## Longboy

Pretty cool Chuck!!! Does the efficiency go up? I imagine it would?


			
				cfellows  said:
			
		

> I don't really have any way of knowing............
> 
> 
> 
> Chuck


   A comparative test between conventional carburation and the vapor carb may answer the "mileage" question. One OZ. of fuel thru the engine at the same load & RPM, which carb allows the most minutes of run time? If you could set that senario up Chuck many of us would like to know. My guess goes to the vapor carb for longest run time.  Dave.


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## MRL

I am a new member here wanted to mention that I built the Jan Ridders model of the vapor fuel tank several months ago but just got around to trying it on my engines in the last couple of days. TOTALLY AMAZING.  I have a small Duclos Witte engine that has always been difficult to start and keep running.  The problem is now solved.  BTW, I found that it required a much richer mixture than on the larger engines.  When I used it with my larger engines, I ended up having to cut the slot in the tube longer in order to have enough adjustment for air (the air adjustment slot is 1/8" wide x 1/2" long).

My next project is to build the "Ball Jar" model referenced on this thread.


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## MRL

Here are a couple of Ridders Tanks I recently completed and put into use.  On the small tank I had enough wall thickness to thread both end caps.  On the larger tank I turned the glass a bit oversize for a press fit (.010 over since the tube was a bit egg shaped) and no O Ring required.

Next project is to try the Glass Jar model.


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## Chicken

Hi!

I have recently converted all my engines to this type of carburetor as it eliminates all problems I encountered.
I started with regular gasoline like used in cars, but this has a very broad range of different substances with different vapor pressures, so first all the light stuff will be pulled out and the heavier stuff will follow later and you constantly have to adjust the extra air screw and eventually the engine will stop even if there is plenty of fuel remaining. Thats when all the easily volatile components of the regular gasoline are removed.
I have now changed to what's called "Waschbenzin" here in Germany and whis is available at my local hardware store for about 5 euro/liter. This is extrapure gasoline with extremely narrow boiling range and still rather high octane rating of about 80. It is clear as water and almost odorless.
There are absolutely no residues and once the air screw is adjusted it will keep running until the fuel tank is completely dry. Only in the first 5 minutes some adjustments need to be made as the tank will cool significantly due to evaporation of the fuel, but this will eventually stabilize.
Even now in winter time this fuel works great. Today I had one of my engines running outside at about 5 °C. My vapor carb cooled to about 0 °C when it reached an equlibrium and the extra air screw was almost completely closed, but the engine run like a charm until all fuel was removed 

This is excellent! Thank you all for the great ideas!

best regards,
Alex


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## AussieJimG

To throttle my version of Jan Ridders' two stroke, I used a screw to limit the travel of the non-return valve in the intake line. This valve is between the extra air adjustment and the engine so it does not affect the mixture. It works, but it very sensitive; requiring constant adjustment to prevent the engine over revving.

Jim


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