Marvel-Schebler carburetor leaking

grapeman

New User
I have a TO20 with a Marvel-Schebler carburetor. Have put a rebuild kit in it and overall it works pretty good. Motor runs and responds well. However, the carb seems to leak when the motor is turned off. Yesterday when I removed the hose the connects the carb to the air filter there was a couple of tablespoons of fuel just lying in the tube.

Anyone got any ideas where to start looking?

Thanks
 
I'd be looking at the oil level. Seen my brother's to20 fill up with gas after leaving fuel on.Only takes a little
flake of rust or dirt under the needle valve.
 
There could be a flake of rust caught in the needle valve. One trick to clear it out is to turn off the fuel,
pull the plug in the bottom of the carb bowl, let it drain into a clean container. Then turn the fuel back
on, it may flush out.

Look at what drained out. If there is rust or grit in it, the tank is contaminated and you'll have problems
until it's cleaned out or replaced.

Some of those old carbs will drip when the fuel is left on, that's common. Always a good practice to turn the
fuel off when done.
 
How to check float level...
Barbed fitting into base of carb. Clear hose on end of fitting. Hold hose
up towards gas tank. Turn on the fuel flow. The level in the hose will
show you the level in the carb.
 

how high should the bowl level be? mine has been like that since I got it, today I opened it up, the previous owner had "rebuilt" it, threw some new parts at it actually, the valve seat was on hand tight I could clearly see a gap between the gasket seat and body, I tightened it but still the same, my float looks awfull they sometime will leak fuel in and become heavy, did not look like it in my case but may be yours,

my thing is I am looking for some tips to doing this right, like how to set the proper level and some initial settings, like the the idle screw and mixture screw, I think rule of thumb is to tighten them and than back off a couple turns, something like that to get started than tune it.

if any of you know better please share
 

Once you find the spec, a handy way to set the gap between the top of the float and the body is by using a drill bit. The spec is usually some very common fraction like 3/32" for example, and we all generally have all most sizes of drill bits around.
 
As far as the adjustments. The float is set at 9/32 from gasket face to top of float. Idle screw is 7/8 and main is 1 1/4 turns. Warm up and fine tune...
 
(quoted from post at 13:00:53 06/26/15) As far as the adjustments. The float is set at 9/32 from gasket face to top of float. Idle screw is 7/8 and main is 1 1/4 turns. Warm up and fine tune...

that's what I read through the forums, just wasn't sure if its for this carb, I read there's a couple other models like zenith for ex,

in my case I found 2 problems, the prev owner had "rebuild" it, the valve body wasn't screwed on tight, and the float was set at less than 1/4 inch, that is for the most part why mine was flooding, I have not yet tried it, I am in the process of replacing the through rods on the block, yeah mine has the cracked block, pad the rods installed a long time ago, I attempted to tighten them and the middle bottom snaped, the others weren't much better, kind of stuck on that now 2 0f the brass plugs wont come out.
 
This may sound stupid but a couple of good whacks with a small ball peen hammer on the end of a screw driver or on the end of a plug while tension is applied will a lot of the time be enough to break them lose. I use anti seize on all bolts ect.
 
(quoted from post at 07:41:43 06/28/15) This may sound stupid but a couple of good whacks with a small ball peen hammer on the end of a screw driver or on the end of a plug while tension is applied will a lot of the time be enough to break them lose. I use anti seize on all bolts ect.

yeah no, I used an impact screwdriver, if you are familiar, 4 came out , barely, the other 2 I broke several hardened bits, one of them the head striped, I drilled them out today and managed to get them out,

I got my carb done, I am hoping to split it tomorrow, I also have the flywheel issue, rewired it and should have something going soon, we'll see if my carb still floods
 

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