Carb bowl fill level (1 Viewer)

[Kschep]

Howdy y’all,

ok so I’m working on a lean drop for my 40 which I have reverse-engineered 70% (I’m guessing lol) oh how I wish my PO was alive - the questions I would ask him...R.I.P prideful cruiser owner...

anyways - I’ve got it running well but rich as you know what. I’m noticing my float level is probably off because when Iook through the hourglass I see it wayy above half. (What is my float adjustment? Meaning: Level too high - adjust is ______ for float? Raising or lowering?

 

[Pighead]

Take the top off the carburetor, turn it upside down (carefully, so little parts don't fall out). See the float, then see the tab connected to the float that is now resting on the end of the fuel inlet valve. You bend that tab to adjust float.

 

[Kschep]

Ya so ... if I took off top turned upside-down (so pin with spring doesn’t pop out) ... look at float now [top turned over] ; so oppo of what it would be normally - sitting on carb normal operation engine running....

what is my adjustment to make level of fuel in bowl LESS .... ? (Bec I have way over half) bend back so higher or bend down so lower

I have manuals btw - just thought someone would know typical adjustment of float of bowl fills over half (84%-94%) <—— lol

 

[Pin_Head]

With the bowl cover off and turned upside down, adjust the float tab that contacts the needle valve so that the float is 7.5 mm above the lid (without gasket). There is a video somewhere on YouTube that shows this.

 

[Kschep]

Right on. ... so I need to lower the tab (on carb top off / and looking at it inverted) - to adjust float level/fuel level in carb LOWER...thx
(Clarification purposes)

 

[Pin_Head]

Yes. Bending the tab down closer to the needle will raise the float with the assembly upside down.

 

[middlecalf]

Float level adjustment will help prevent carb flooding and/or fuel starvation, but won’t help the rich running issue.

 

[Pin_Head]

How do you know it is running rich? This is a serious question because running rich produces carbon monoxide which is odorless. It is not easy to know if it is running rich. If you smell gasoline from the tail pipe, it is misfiring.

 

[Kschep]

It’s a thick black smoke - and with that smoke it spits out black “stuff” that sprays on the car next it when I start it. It’s embarrassing. That and it’s really smelly when I run it - I desire less smell...therefore I figured it was “rich” meaning too much fuel being fed

...
So I know the mixture screw is 1.5 turns out for starting a retune but where do I start the TP screw and also the Fast Idle screw? To make them back to starting position so I can do a lean drop on them?

 

[samatulich]

You could be burning oil due to leaking valve stem guide seals. Mine does the same thing. On initial startup, it makes a mess. Also, under vacuum (engine breaking), it puffs smoke out the tail pipe. It is my understanding that running rich or lean has to do with the jet sizes, not the fuel level in sight glass window.

 

[Kschep]

Ya no I know it’s not like fuel now level but I figured rich was something related to getting fed too much of something.
So your saying my carb is burning too much oil possibly?

 

[Pighead]

Thick black smoke does usually indicate running rich, burning oil gives off a white smoke from the tailpipe. It is possible that with an over-full float bowl that un-metered gas spills into the intake...

 

[Pin_Head]

When you have the top cover off, check that the power valve piston moves freely. A power valve stuck open will make it run rich. Make sure that the choke is all the way open.

The throttle positioner and high idle have angular measurement specifications on the throttle butterfly plate., but you can also adjust the speed after you have it running to give about 1200 RPM for both of them.

 

[Kschep]

Choke opens and closes freely..will check power p
Definitely black smoke with some form of liquid in there because the black spots that spray out on start u / while running it’s like mini globules of black sludge. Worse with choke on obviously

in regards to checking the bowl level - my fluid level fluctuates from mid-level to extremely high (I have to lower my head toway below the carb just to see it) - random guess but it’s like 90%+ full just to give you an idea. My question is: based on the fluctuation I’m seeing, what is the proper time to check the level - just car sitting off, after firing it while it’s idling, etc.

Ok for tuning - what does it mean when nothing happens no matter what I do to the mixture screw - given that the first step in tuning is: after warming up vehicle to be able to run w/o choke on .. “run engine to obtain fastest idle speed by adjusting the idle mixture screw”

 

[Pin_Head]

Fluctuating bowl level is likely a bad / dirty needle valve and seat. It could also be a bad float, but that is not typically an intermittent problem.

If nothing happens (E.g. engine quits) when you turn the mixture screw all the way in, this means that either you have a manifold vacuum leak or the idle fuel circuit is not delivering fuel. It also means that you have had to screw the idle speed screw in to open the throttle plate so it is running off the main jet with fuel dribbling out of the primary main nozzle. This is often accompanied with a bogging down during acceleration off idle. It is a common problem on 2Fs of this vintage. It may also explain the smoke and gasoline smell at idle.

 

[Pighead]

Fluctuating bowl level is likely a bad / dirty needle valve and seat. It could also be a bad float, but that is not typically an intermittent problem.

If nothing happens (E.g. engine quits) when you turn the mixture screw all the way in, this means that either you have a manifold vacuum leak or the idle fuel circuit is not delivering fuel. It also means that you have had to screw the idle speed screw in to open the throttle plate so it is running off the main jet with fuel dribbling out of the primary main nozzle. This is often accompanied with a bogging down during acceleration off idle. It is a common problem on 2Fs of this vintage. It may also explain the smoke and gasoline smell at idle.

Um, yeah. What he said.

 

[Beehanger]

Um, yeah. What he said.

Having similar issues. Did this ever get resolved? I've got a gas leak coming from underneath where the float is, I replaced the base plate gaskets there and something is still leaking. It seemingly impossible to tune, I've got about 10-11 Hg in a vacuum. Intake and exhaust are sealed up, but carb could be leaking vacuum (chinese carberator)

@Kschep what did your issue end up being?

@Pin_Head if both of the screws are screwed in during running as you mentioned, could the vehicle still run with the issue you are speaking of? Rebuilt everything on the carb except needle valve and can't tell if its the carberator or a vacuum leak on the carb mating surface/base of carb that's creating my untunable engine.

thanks,
Dan