Webster carb & fuel tank question

[Johann]

Hi All,
From what I read in the forums, I need to use 0.12 or 0.15 size carb to get the Webster running. Problem is that I have a 0.60 carb lying around. Any suggestions or possibilities to perhaps modify it to do the the job ? I would also like to know if a press fit with Locktite would seal the end caps of the tank ? It is so messy to go the soldering route ? Anybody done this before ?

Best regards to you all

 

[bobsymack]

Hi Johann
Why dont you use Jan Ridders design of a vapour carb which is incorporated in the fuel tank and I would imagine there should be no problem in using loctite as
these are resistant to petrol.
Regards Vince

 

[Johann]

Hi Vince,
Good idea.
Many moons ago I built a wood gas generator, and used a similar method to regulate the air to gas ratio. BUT it was a deamon to get going in the beginning. Later on it was a mere formality to start up, but still a process you needed
lot of patience for. Every morning early, and every night. Had dairy cattle to milk.
Now, back to the Webbie. Do you have experience with running a Jan Ridders carb on a engine that it was not designed for ? Should I follow that route, what potholes must I look out for ? I am curious to know if the tank level wil have a critical influence on the vapor volume or intensity ?
Thanks for the feedback
Johann

 

[bobsymack]

Hi Johann
Why dont you make a vapour carb out of a small glass jar first and experiment with this the main thing is that you have some sort of air bleed to make the mixture lean or rich,you need to be careful of blowback and maybe should have a check valve in the fuel line.
Regards Vince

 

[Johann]

Thanks Vince, you have planted a new seed in my head....

 

[Rustkolector]

Johan,
I am a little late to this thread, but as a suggestion, why not try propane fuel. Clean, almost odorless, and much less troublesome once set up properly. With gaseous fuel, carb size is not a big problem as you don't have to worry about the venturi size needed for good fuel atomization. If you carb is oversized for the engine, you can install an orfice plate ahead of the venturi to create adequate fuel draw at the fuel inlet. It takes a little experimentation to get the hole size just right in the orfice plate (usually smaller than you would think it should be). You will also need a demand regulator http://www.homemodelenginemachinist.com/f26/propane-i-c-engines-20266/ and a propane bottle pressure regulator (Webber portable gas grill type i.e. "Go Anywhere Grill"). I believe the Webster is a throttle governed engine. If so, a two jet carb (like Jerry Howell's two jet throttle) works very well on propane. If you want to stay with an RC type carb, it works fine at as a constant speed carb. For variable speed with an RC carb, a little fine tuning with the orfice plate will get the throttle to work pretty well.

One thing about propane is that it requires an open crank engine to have an external cylinder lubrication source like a drip oiler. If you use gasoline or camp fuel, a little oil (50:1 straight oil) will work fine without the drip oiler, but little black oil droplets are always existing the exhaust.

Jeff

 

[Johann]

Hi Jeff,
Thanks for a lot of valuable information. As it happens to be, I have a pressure regulator lying around..suppose I am a bit of a squirrel, cannot get rid of anything that I might need later. Unfortunately the other half cannot understand this..ha ha.
Today I must complete cutting the timing gears first.
You haven't perhaps have plans for a double needle type carb lying around ?
Johann

 

[Johann]

Sorry, meant two jet carb..

 

[Rustkolector]

Johan,
I would start with an RC single jet carb. The Enya and OS carbs seem to work the best for me. Something with a .140" to .180" dia or smaller throat should work with propane. You can get reasonable throttle response with a little fine tuning of the orifice plate. If you want a wide range of throttle response use Jerry Howell's 2 jet throttle. You can buy his plans at the link below.

Another thought for variable speed is to build in an easly adjusted ignition advance and retard into you engine. You can get a surprising amount of speed variation by varying ignition timing.

Jeff


http://www.model-engine-plans.com/engineplans/combustion/howell2jet.htm?18,17

 

[stevehuckss396]

Hi All,
From what I read in the forums, I need to use 0.12 or 0.15 size carb to get the Webster running. Problem is that I have a 0.60 carb lying around. Any suggestions or possibilities to perhaps modify it to do the the job ? I would also like to know if a press fit with Locktite would seal the end caps of the tank ? It is so messy to go the soldering route ? Anybody done this before ?

Best regards to you all

I would use the carb called out for it. It's already proven to work.

Fuel tank soldering is not as bad as you think. I make my tanks so the end caps insert into the tank. I ring the tank with a piece of solder, push the endcap into the tank, and set it down onto the end cap. Heat with a propane torch for about 10 seconds and your done. Clean well and flux and she won't leak.

 

[Johann]

I have completed the fuel tank by machining the end caps to a nice press fit tolerance. Pressed in with locktite seems to be sufficient, as it seems to be airtight if you suck the filler and holding the outlet closed. Perhaps not the best of tests, but bearing in mind that we don't have any pressure in the tank, I am holding thumbs..

 

[Johann]

By the way Steve, nice finish on that tank. Do you buff the part to get to that finish, or is there some other secret ? The micro fine machining marks can be a problem to remove...?