zenith carb

[wbs]

see attached sketch;hope it goes
Zenith carb , found in junk parts, the carb fails to to shut gas flow into it. When removed from car and inverted, flow will shut off. So fuel needle valve is ok. When carb top and bottom bodies separated and looking into bowl i notice next to compensator jet there is a channel in bowl going to air horn . the channel hole is below the fluid level. the float has no leaks into it which would cause it not to float.
So the float will never rise to normal fluid level and gas will leak into air horn and flood the motor.
The channel must have been made by factory, no owner could have created it.
Andrews book does not show the hole or channel or a plug of hole.

Ques-any ideas-mssing plug&why not shown in Andrews book? I’m going to plug hole but of course i wont be able to use brass drain plug to drain bowl.

Opinion way it should have been made- the drain plug should be in bowl and not in air horn.

[redmodelt]

What you are calling a drain is the plug for one of the jets and also acts as bowl drain not just as a drain. Are you missing one of the jets? Go down to Aug 24 posting;
https://forums.aaca.org/topic/240876...t-idle/page/2/
Could also, if jet is not missing, be the float level is set wrong and fuel is flowing out one or more jets into the air horn.

[wbs]

thanks for the reply- its definitely not a float level setting problem -the normal float setting is parallel to the upper body and i have even set float lower than that and used a spring assist to no help---i'm really surprised that Mr. Andrews picture does not show the channel--but i am going to check out the main jet more closlely i am always thank ful for ideas

[30 Closed Cab PU]

Can you post a picture?

[redmodelt]

Did you look at the link I posted. There is a real good moving diagram that shows fuel flow.

[CT Jack]

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If you remove the top half of the carburetor and hold the lower half in your hand and fill the bowl with water it shouldn't leak. If it does something is missing like a jet, a washer or there is a hole or crack in the casting. If this test proves to be okay then you have a shut off valve that is No Good. Maybe this is why the carburetor was in the pile of junk parts.

[wbs]

thanks to all who have replied - i have not had a chance to do anything with the carb --maybe carb is junk but hoping to check it for cracks, look at info flow, but i 'm thinking the prob is the venturi jet-- sorry i dont have digital camera

[Gary WA]

http://modelabasics.com/home.htm

[Gary WA]

Post #8 excellent info on Carbs,etc he does a Great job on his site.

[redmodelt]

Same info I posted only the pictures are a bit larger.

[30 Closed Cab PU]

Originally Posted by redmodelt

Same info I posted only the pictures are a bit larger.

Just as an FYI, I did not see the info the 1st time, did not scroll down far enough once the link was opened, was not sure which post you wanted to be seen.

[redmodelt]

Yes I see now there was no time stamp to have references to, just dates. I mean the photos in the link you posted are larger then the ones I posted the link too.

[wbs]

hello - i took red's and others advice and replaced main venturi jet and leak has stopped---thanks-- what are initial settings of needle valves?-as turn in needle til get to a stop , then turn out ccw a certain number of turns for idle and run valves?

[ryanheacox]

Originally Posted by wbs

hello - i took red's and others advice and replaced main venturi jet and leak has stopped---thanks-- what are initial settings of needle valves?-as turn in needle til get to a stop , then turn out ccw a certain number of turns for idle and run valves?

Idle needle rule of thumb is start at 1 1/2 turns out. As far as the GAV, start with 1/4 to 1/2 turn.