The Ford Barn

jerrytocci · 07-12-2023, 10:02 PM

I have a pro rebuilt and it drips. What should I look for. Gas seems to drip from vent hole. Float is set at 3/4"

Rob Doe · 07-13-2023, 03:41 AM

Jerry, if I recall correctly, the float should be at 5/8". If debris enters the carb, all bets are off regarding any recent rebuild. I used Steve Pargetters Zenith restoration book.

Your fuel valve may be leaking under the tank or on the firewall for late 31's.

old31 · 07-13-2023, 07:57 AM

Clean out the needle valve and then change the float level to 5/8"

Then check your shutoff to see why that is allowing fuel into the carb.

jerrytocci · 07-13-2023, 10:12 AM

Any thoughts on an inline filter. I have one in the shut off. I leave the shut off in the on position, unless car sits for a while.

Bob Bidonde · 07-14-2023, 10:15 AM

These slides may help you:

Gene F · 07-14-2023, 01:16 PM

Sponsored Links (Register now to hide all advertisements)

While you have it open, the big long jet should have a dished end on it...

stickshift · 07-16-2023, 05:38 PM

Boy! It's hotter than a two dollar pistol here. I set my wrenches on the step plate and couldn't touch them after a minute. Anyway I'm glad this subject came up because my Zenith has had a problem the last couple months. My engine would only run with the idle mixture adjustment screw closed and the GAV open three turns. Also back-firing when engine braking down hill. I had the carb apart before, but nothing was plugged. I pulled it apart yesterday and the same, nothing was plugged, soaked all the brass parts overnight and reassembled today. I did find two things that I corrected... One of the jets in the venturi was lower than the other so I shimmed it to be at the correct height in Bob's slide show he posted. The other thing was the float was a little high. Shimmed the ball valve with a thicker washer so the float shuts off the valve at 5/8". Reinstalled the carb, Lo and Behold it purred like a kitten. GAV shut and idle mixture screw at 1 3/4 turns open. I was able to get the idle down to 400 RPM without stalling, but ended up leaving it at 550 RPM. Thanks to Bob Bidonde for the slides, and Tom Endy for the write-up on Zenith Carburetor Documentation. Both were instrumental. I'm going to have a tall glass of iced tea and stay inside for the remainder of the day.

nkaminar · 07-16-2023, 07:22 PM

A good site for information on the Zenith carburetor is https://model-a.org/default.html. The site identifies 6 common causes of gasoline leaking out of the carburetor.

nkaminar · 07-16-2023, 07:28 PM

See related thread, https://www.fordbarn.com/forum/showthread.php?t=328786

KenBolton · 07-17-2023, 08:45 AM

Bob, those slides are nice! How could I get a copy??

nkaminar · 07-17-2023, 10:01 AM

Ken, Can you do a screen print on your computer?

Waorani · 07-17-2023, 01:18 PM

If you're on a PC - click on image to open, then right click & save image as. Not sure on phone.

Del in NE Ohio · 07-17-2023, 03:10 PM

Was just helping a guy with a dripping Zenith. When I removed the drain plug, the main jet fell out! Re installed, tightly, . Carb no longer drips!

Gene F · 07-19-2023, 08:21 PM

Quote:

Originally Posted by Del in NE Ohio

Was just helping a guy with a dripping Zenith. When I removed the drain plug, the main jet fell out! Re installed, tightly, . Carb no longer drips!

I am amazed it even ran like that.

Bob Bidonde · 07-20-2023, 09:09 AM

To copy my slides, click on them one at a time and do a "Save As."

katy · 07-21-2023, 10:41 AM

Bob Bidonde, thanks for the info about the 1/8" vent hole, I dropped the bowl assembly off my A yesterday and found no vent hole, so I did the mod as listed. Haven't ran the engine yet. Just wonderin' if you know what differences if any I might experience.
Respectfully, Ken

07-12-2023, 10:02 PM	#1
jerrytocci Senior Member Join Date: Aug 2020 Posts: 235	Zenith drips I have a pro rebuilt and it drips. What should I look for. Gas seems to drip from vent hole. Float is set at 3/4"

07-13-2023, 03:41 AM	#2
Rob Doe Senior Member Join Date: Apr 2021 Location: Central Illinois Posts: 494	Re: Zenith drips Jerry, if I recall correctly, the float should be at 5/8". If debris enters the carb, all bets are off regarding any recent rebuild. I used Steve Pargetters Zenith restoration book. Your fuel valve may be leaking under the tank or on the firewall for late 31's. __________________ "It ain't what you know for certain that gets ya in trouble. It's what ya know for certain that just ain't so!"

07-13-2023, 07:57 AM	#3
old31 Senior Member Join Date: Jan 2016 Posts: 2,103	Re: Zenith drips Clean out the needle valve and then change the float level to 5/8" Then check your shutoff to see why that is allowing fuel into the carb.

07-13-2023, 10:12 AM	#4
jerrytocci Senior Member Join Date: Aug 2020 Posts: 235	Re: Zenith drips Any thoughts on an inline filter. I have one in the shut off. I leave the shut off in the on position, unless car sits for a while.

07-14-2023, 01:16 PM	#6
Gene F Senior Member Join Date: Mar 2012 Location: Ohio Posts: 1,973	Re: Zenith drips Sponsored Links (Register now to hide all advertisements) While you have it open, the big long jet should have a dished end on it...

07-16-2023, 05:38 PM	#7
stickshift Senior Member Join Date: Jan 2023 Location: Grass Valley, Ca Posts: 247	Re: Zenith drips Boy! It's hotter than a two dollar pistol here. I set my wrenches on the step plate and couldn't touch them after a minute. Anyway I'm glad this subject came up because my Zenith has had a problem the last couple months. My engine would only run with the idle mixture adjustment screw closed and the GAV open three turns. Also back-firing when engine braking down hill. I had the carb apart before, but nothing was plugged. I pulled it apart yesterday and the same, nothing was plugged, soaked all the brass parts overnight and reassembled today. I did find two things that I corrected... One of the jets in the venturi was lower than the other so I shimmed it to be at the correct height in Bob's slide show he posted. The other thing was the float was a little high. Shimmed the ball valve with a thicker washer so the float shuts off the valve at 5/8". Reinstalled the carb, Lo and Behold it purred like a kitten. GAV shut and idle mixture screw at 1 3/4 turns open. I was able to get the idle down to 400 RPM without stalling, but ended up leaving it at 550 RPM. Thanks to Bob Bidonde for the slides, and Tom Endy for the write-up on Zenith Carburetor Documentation. Both were instrumental. I'm going to have a tall glass of iced tea and stay inside for the remainder of the day. __________________ Stickshift 1915 Model T touring 1931 Ford Model AA Flatbed

07-16-2023, 07:22 PM	#8
nkaminar Senior Member Join Date: Jan 2012 Location: Western North Carolina Posts: 3,899	Re: Zenith drips A good site for information on the Zenith carburetor is https://model-a.org/default.html. The site identifies 6 common causes of gasoline leaking out of the carburetor. __________________ A is for apple, green as the sky. Step on the gas, for tomorrow I die. Forget the brakes, they really don't work. The clutch always sticks, and starts with a jerk. My car grows red hair, and flies through the air. Driving's a blast, a blast from the past.

07-16-2023, 07:28 PM	#9
nkaminar Senior Member Join Date: Jan 2012 Location: Western North Carolina Posts: 3,899	Re: Zenith drips See related thread, https://www.fordbarn.com/forum/showthread.php?t=328786 __________________ A is for apple, green as the sky. Step on the gas, for tomorrow I die. Forget the brakes, they really don't work. The clutch always sticks, and starts with a jerk. My car grows red hair, and flies through the air. Driving's a blast, a blast from the past.

07-17-2023, 08:45 AM	#10
KenBolton Senior Member Join Date: Jun 2020 Location: Fall Creek, WI Posts: 213	Re: Zenith drips Bob, those slides are nice! How could I get a copy??

07-17-2023, 10:01 AM	#11
nkaminar Senior Member Join Date: Jan 2012 Location: Western North Carolina Posts: 3,899	Re: Zenith drips Ken, Can you do a screen print on your computer? __________________ A is for apple, green as the sky. Step on the gas, for tomorrow I die. Forget the brakes, they really don't work. The clutch always sticks, and starts with a jerk. My car grows red hair, and flies through the air. Driving's a blast, a blast from the past.

07-17-2023, 01:18 PM	#12
Waorani Member Join Date: May 2023 Location: Opelika, AL Posts: 43	Re: Zenith drips If you're on a PC - click on image to open, then right click & save image as. Not sure on phone.

07-17-2023, 03:10 PM	#13
Del in NE Ohio Senior Member Join Date: May 2010 Location: Columbiana,OH Posts: 461	Re: Zenith drips Was just helping a guy with a dripping Zenith. When I removed the drain plug, the main jet fell out! Re installed, tightly, . Carb no longer drips!

07-20-2023, 09:09 AM	#15
Bob Bidonde Senior Member Join Date: May 2010 Location: Long Island, NY Posts: 3,472	Re: Zenith drips To copy my slides, click on them one at a time and do a "Save As." __________________ Bob Bidonde

07-21-2023, 10:41 AM	#16
katy Senior Member Join Date: Jun 2015 Location: Red Deer, Alberta Posts: 5,046	Re: Zenith drips Bob Bidonde, thanks for the info about the 1/8" vent hole, I dropped the bowl assembly off my A yesterday and found no vent hole, so I did the mod as listed. Haven't ran the engine yet. Just wonderin' if you know what differences if any I might experience. Respectfully, Ken __________________ If you don't hear a rumor by 10 AM, start one!. Got my education out behind the barn!