Carburator and fuel line question

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Thanks Luc,
In this case I should have planty of fuel to run it before getting to that point.
 
I built an engine that had the fuel tank pretty low relative to the carb. I made a simple check-valve with a stainless steel ball bearing as the check. It would hold the fuel once it raised it to the carb.
 
Borna---I asked that same question when I built my first couple of i.c. engines. The answer is not a simple one, but the bottom line is that if any of the fuel sets higher than the carburetor, and the carburetor doesn't have a float and needle combination like an automobile, the engine will flood very badly and not run properly. No fuel should set higher than the carburetor because gravity will make the fuel run constantly and deliver too much to your engine. On the other hand, these small engines don't create a lot of "air flow" at the carburetor, and it is the inflowing air thru the carburetor that due to venturi effect will create a slight vaccum to lift the fuel from a lower level into the carb. So---you don't want the fuel level too far below the carb either, or it will be difficult to start. The ideal condition is that when the fuel tank is full, the top level of the fuel should be about 1/8" below the carburetor, This will prevent gravity flooding and also hard to start condition due to having to "lift" the fuel too far. A check valve/ball isn't a bad idea, but not absolutely necessary.---Brian
 
Borna not really
HI I don't think it would matter the final answer would be the fuel level in your tank
was my respond
I assume that you knew about the float, i will make it simpler fuel level 1/8 max lower tan the carb

cheers


 
Borna, You don't HAVE TO lower the tank. That being said, it appears that you do have a lot of your tank higher than the carburetor. How will you know when filling the tank that the amount of fuel in the tank has reached the level where it becomes higher than the carburetor? No matter how many people scream at me in large red letters, I think that lowering the tank untill the inside top of the tank is about 1/8" below the level of your carburetor will save future headaches.---Brian
 
Brian Rupnow said:
Borna, You don't HAVE TO lower the tank. That being said, it appears that you do have a lot of your tank higher than the carburetor. How will you know when filling the tank that the amount of fuel in the tank has reached the level where it becomes higher than the carburetor? No matter how many people scream at me in large red letters, I think that lowering the tank untill the inside top of the tank is about 1/8" below the level of your carburetor will save future headaches.---Brian
Click to expand...
Brian,
instead of assuming why don't you ask,:rolleyes:
I simply put these letters in red instead of posting the complete articles
I have enought guts to reply to someone when I dont like their comments
I guest some people don't
 
Luc--I don't want to have a problem with you. Especially since you are a fellow Canadian. If you post something in big red letters directly after someone elses post, and don't specify why you have done that, the implication is that you are shouting at the previous poster. Then to make a comment about who does or doesn't have "GUTS" certainly doesn't appear to be offering an olive branch. This topic is especially important to me, because when I built my first I.C. engine I encountered serious problems with it. It would start, run for 10 or 12 seconds and then quit. I asked for advice about gas tank height, and got many conflicting answers, some which were outright, absolutely wrong, or so ambiguous that they were meaningless. It wasn't untill someone took the time to explain the reasoning behind their answer that it began to make sense to me, and I was able to correct the problem and have a good running engine. We are on this board to showcase our own machinery and to help others who may not have the experience that we do. Not to make derogatory statements about other posters nor trade insults. There are other forums that specialize in that.----Brian
 
Brian Rupnow said:
Luc--I don't want to have a problem with you. Especially since you are a fellow Canadian. If you post something in big red letters directly after someone elses post, and don't specify why you have done that, the implication is that you are shouting at the previous poster. Then to make a comment about who does or doesn't have "GUTS" certainly doesn't appear to be offering an olive branch. This topic is especially important to me, because when I built my first I.C. engine I encountered serious problems with it. It would start, run for 10 or 12 seconds and then quit. I asked for advice about gas tank height, and got many conflicting answers, some which were outright, absolutely wrong, or so ambiguous that they were meaningless. It wasn't untill someone took the time to explain the reasoning behind their answer that it began to make sense to me, and I was able to correct the problem and have a good running engine. We are on this board to showcase our own machinery and to help others who may not have the experience that we do. Not to make derogatory statements about other posters nor trade insults. There are other forums that specialize in that.----Brian
Click to expand...
Here is your quote:

If you post something in big red letters directly after someone elses post, and don't specify why you have done that, the implication is that you are shouting at the previous poster.

those big red letters were not after your post but Borna's I didn't whant him to start moving the thank around
His quote:

Thanks for the tip Brian,
So looking at the picture I can say I need to lower the length of the tank?

like you said this forum is to help someone and not to side track him
and if what he understood was to move his tank around was wrong
anyway I hope that this want turned out in ww4
cheers
 
First thanks for all the comments.
Sorry but I am still a little confused.
The length the tank is 3”. Assume I make it in a way that the top of the tank is 1/8” below the carburetor. Let say now the engine is working and tank become 1/2 empty, therefore now the fuel is about 0.625” below the carburetor. Does this cause any issue as if is hard for the carburetor to pull the fuel in?

Thanks
Borna
 
Borna---Unless you plan on running your engine for hours at a time, I would suggest that you reduce the height of your tank to about 1". That will still give you lots of fuel for running times up to 1/2 an hour. These small air cooled engines are prone to overheating, so I doubt that you will want to run it more than 10 minutes at a time anyways. The shorter height tank also gets around the issue of having to lift the fuel to far on start up. Of course, you can get around the 'high lift" by putting in a ball check valve like someone else has suggested so that the fuel doesn't fall away from the engine due to gravity when the engine is shut off. That way you can still keep the full height tank and just lower it so that you don't get a gravity feed of fuel into the carburetor. If you plan on starting the engine by hand, its very important not to have to lift the fuel up very far. If you use an electric drill to start it, then it will eventually pull the fuel up from a lower height.
 
Hi Brian,
I think I am almost there
so you said "I would suggest that you reduce the height of your tank to about 1".
Is that 1" above or below carb?
 
That is the total height/length of the tank. Your current tank is too long, at 3". You should cut 2" out of the existing tank so that it is only 1" high, or long, depending on how you want to say it. The top of the shortened tank should be 1/8" below the carburetor.
 
Now I got it. Thanks
The tank itself is too long because is installed vertically. The size is ok if I would have installed it horizontally with 1/8" below carb.
 
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