Box Stock

carb ruxing and sp low speed side

foreverfaster

foreverfaster

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have done some research, but love to hear what the people on this page have to say.. seems my education here is always better than what i find on my own.
PLEASE correct my terms as needed. lots of little questions
ASUMPTIONS:
when the choke plate is closed it forces more air down the idle (low speed) air inlet and the main emulsion tube air feed. more air forced in these two areas forces more fuel through them. thus a very rich situation. making the assumption that both will supply fuel???, not just the low speed side.?

once the choke is opened, the throttle butterfly being closed to some degree keeps some air still going down these two passages, fuel leaks, pushed or vacuumed out of the 4 prick holes just beyond the butterfly.
What does the screw and needle just beyond these holes do? from diagrams it is clear it is an extension of the tube that leads emulsified fuel to the 4 prick holes.
backing the screw / needle from its seat does what?

Lets assume the carb has an etube with 2- .0245 holes for the low speed, low speed jet is a .022. for argument it also has 3 .0285 holes up the e tube, 4 rows followed by 2 holes 4 rows.
 
Where is Al when you need him?

Al was correct when he stated air is pushed into engine by atmospheric pressure.
Air always travels from high pressure to low pressure.
Low pressure is created by the piston descending in the bore.
Atmospheric pressure also acts on the fuel in the float bowl, pushing it thru the restriction of the jet, toward the low pressure area..
Liquid fuel will not burn.
Air bleeds and emulsion tubes premixes air and fuel to help it vaporize.

Closing the choke restricts the atmosphere from pushing air into the engine.
The float bowl, as well as the air bleeds, gets its atmospheric pressure before the choke. So the balance of fuel flow is greater in relation to air flow. As in, the mixture is richer. The fuel is still vaporized by the air entering through the air bleeds and emulsion tube.

Likewise, changing the size of the air bleeds and holes in the emulsion tubes alters the amount of air mixed with the fuel at the vaporization point.

The size of the emulsion tube holes affects the size of jet needed to achieve the correct overall air-fuel ratio.

Maybe a little simplified.

Hope that helps.
 
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95 shaw said:
Where is Al when you need him?

Al was correct when he stated air is pushed into engine by atmospheric pressure.
Air always travels from high pressure to low pressure.
Low pressure is created by the piston descending in the bore.
Atmospheric pressure also acts on the fuel in the float bowl, pushing it thru the restriction of the jet, toward the low pressure area..
Liquid fuel will not burn.
Air bleeds and emulsion tubes premixes air and fuel to help it vaporize.

Closing the choke restricts the atmosphere from pushing air into the engine.
The float bowl, as well as the air bleeds, gets its atmospheric pressure before the choke. So the balance of fuel flow is greater in relation to air flow. As in, the mixture is richer. The fuel is still vaporized by the air entering through the air bleeds and emulsion tube.

Likewise, changing the size of the air bleeds and holes in the emulsion tubes alters the amount of air mixed with the fuel at the vaporization point.

The size of the emulsion tube holes affects the size of jet needed to achieve the correct overall air-fuel ratio.

Maybe a little simplified.

Hope that helps.
Click to expand...
you are 100 % ...My problem is i can i can explain it to you but i can't understand for you .
 
combative hodaka said:
you are 100 % ...My problem is i can i can explain it to you but i can't understand for you .
Click to expand...
I've found trying to explain things will sometimes alter my approach to understanding them.
Same as push vs suck in my above post.
One approach always leaves some unexplainable gaps in what is actually happening.

Writing on this forum, trying to make things understandable, without the gaps, has helped a lot.
 
So if it is a push instead of a suck what is the reason for the carb to suck your hand when placing it over the carb. Also, if you take the rings off the piston will it push or suck. Asking for a friend
 
Still moving from high pressure (atmosphere) to low pressure areas.

Does the piston without rings create a low pressure area?
 
so the " idle screw" when backed out will increase emulsified fuel behind the throttle plate increasing a rich situation and increase rpm at idle?
assuming this allows fuel in excess of the 4 prick holes can accomplish ??
 
There isn't enough pressure differential at the emulsion tube , at idle for fuel to be pushed up .
Backing the screw out will richen the idle , too the point of where the idle pick hole is in control .
 
foreverfaster said:
so the " idle screw" when backed out will increase emulsified fuel behind the throttle plate increasing a rich situation and increase rpm at idle?
assuming this allows fuel in excess of the 4 prick holes can accomplish ??
Click to expand...
No, idle rpm should not increase. Usually increase is result of lean condition.

The main circuit only comes into play after throttle blades are open enough to make the low pressure area extend beyond the top of the emulsion tube.

I'm trying to remember if the idle mixture screw affects the air, or the fuel part on a clone carb.
Lo206 screw adjusts the air to the idle mixture.

The other thing is the throttle blades need to uncover the idle holes to engage the idle circuit.
 
95 shaw said:
Still moving from high pressure (atmosphere) to low pressure areas.

Does the piston without rings create a low pressure area?
Click to expand...
To further this thought, liken this to putting your hand over the drain in a full bathtub. Is your hand pushed to the drain, or sucked to the drain? Still high pressure moving to low pressure.

Likewise, a hole in your garden hose sprays water in the air. Is the atmosphere sucking water out of the hose?
Again, high pressure moving to low pressure.

Just some thoughts.
 
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95 shaw said:
To further this thought, liken this to putting your hand over the drain in a full bathtub. Is your hand pushed to the drain, or sucked to the drain? Still high pressure moving to low pressure.

Likewise, a hole in your garden hose sprays water in the air. Is the atmosphere sucking water out of the hose?
Again, high pressure moving to low pressure.

Just some thoughts.
Click to expand...
I really like this analogy..
Perfect example .
Nothing would leak if a vacuum was required .
I think of Al every time i use a shop vac . Watching the loose material get pushed up the hose !
Still hard to fathom .
 
flattop1 said:
There isn't enough pressure differential at the emulsion tube , at idle for fuel to be pushed up .
Backing the screw out will richen the idle , too the point of where the idle pick hole is in control .
Click to expand...
"Backing the screw out will richen the idle" This is what i was looking for !
I'm trying to dig through all the comments, and analogies, assuming the piston dropping in the cylinder causes a vacuum (low pressure) drawing fuel air mixture through the low speed (idle circuit) does the fuel come out the 4 prick holes and around the idle needle?? wish i had the time and tools to video this process to see and understand better how it works.

one more thing. will a engine run if you block the etube from low speed pick up to the top of the etube?? just allowing fuel through the low speed side. i thought about maybe doing this as an experiment??
 
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