The Ford Barn

cars2cool · 12-05-2022, 09:26 AM

How critical is it to have the 2 halves of the Zenith-1 and Zenith-2 (Holley) matched? As well as the 2 different floats also? I have one on my bench now that has been giving the owner a fit this summer. He just bought the late '31 pickup and has been working out some of the bugs while still driving it this last summer. The float needle valve has been suspected culprit of intermittent leaking. Upon getting the carb. removed and on my bench, I found the 2 different manufacturers upper and lower castings and the cap jet finger tight. Single gaskets under the jets as they should. The gasket surfaces of the upper and lower halves of the carb. are corroded as well as the surface to the intake manifold. I already have the Paul Moller book and the red bible for reference material and I have Dave Renner on speed dial. But I wanted to put this up here to save him a bunch of phone calls answering the same question a hundred more times. Thanks in advance.

Fullraceflathead · 12-05-2022, 10:30 AM

They're both made from the same blueprints. A purest will spot the mismatch externally. They just won't look right. It's kind of like wearing 2 different colored socks, they both fit well but they just don't look right.
If it’s a driver, use what you got.

Gary WA · 12-06-2022, 06:57 PM

You can use any top or bottoms, except for side bowl-any bottom can be used,or double venturi bottom can be used with any zenith top- as long as not worried about point judging.

CA Victoria · 12-06-2022, 07:52 PM

About half of the floats I have seen have some sort of deformity. This could affect the fuel level in the bowl. After minor corrections use the clear sight tube that screws into the lower plug below the main jet to get an accurate read on the fuel level in the bowl.

Joe K · 12-06-2022, 09:58 PM

You can check the float for a hole by submerging the float in a pot of boiling water. The water heats up the air within the float and a leak will be immediately apparent by the trail of bubbles.

Joe K

Gary WA · 12-07-2022, 06:32 PM

Sponsored Links (Register now to hide all advertisements)

Site Index (Model-A.org)check jets for proper length and dished on ends,flow test if you can. and ensure they are tight with one gasket-none on idle jet, file and clean up both surfaces for flatness.

Ed in Maine · 12-08-2022, 04:49 PM

I recently worked on a carb for a club member that was leaking. I thought that this carb may have been put together with other tops or bottoms. What was a problem is that there was no 3/32 vent hole in the lower casting at the top of the bowl. The vent hole in the upper casting was plugged with dirt. When we were testing float level, we saw the strangest thing. As the gas filled the bowl we had two streams of gas suddenly come up out of the upper casting. Of course we had gas going all over the bench! It definitely was a candidate for complete rebuild. Ed

cars2cool · 12-10-2022, 08:28 AM

Thanks Ed, I double checked the castings after reading this. I ran a piece of tag wire through the upper vent hole and flushed with WD40. Nothing unusual found, no debris.

CA Victoria · 12-10-2022, 12:59 PM

Great suggestion Ed. I have a couple of spare tops to try it on.
I think I will pre drill the plugs to allow more contact with the brass.

12-05-2022, 09:26 AM	#1
cars2cool Senior Member Join Date: Jun 2010 Location: Sioux City Iowa Posts: 196	Zenith to Holley mismatch How critical is it to have the 2 halves of the Zenith-1 and Zenith-2 (Holley) matched? As well as the 2 different floats also? I have one on my bench now that has been giving the owner a fit this summer. He just bought the late '31 pickup and has been working out some of the bugs while still driving it this last summer. The float needle valve has been suspected culprit of intermittent leaking. Upon getting the carb. removed and on my bench, I found the 2 different manufacturers upper and lower castings and the cap jet finger tight. Single gaskets under the jets as they should. The gasket surfaces of the upper and lower halves of the carb. are corroded as well as the surface to the intake manifold. I already have the Paul Moller book and the red bible for reference material and I have Dave Renner on speed dial. But I wanted to put this up here to save him a bunch of phone calls answering the same question a hundred more times. Thanks in advance.

12-05-2022, 10:30 AM	#2
Fullraceflathead Senior Member Join Date: May 2012 Location: Chillicothe, Missouri Posts: 1,176	Re: Zenith to Holley mismatch They're both made from the same blueprints. A purest will spot the mismatch externally. They just won't look right. It's kind of like wearing 2 different colored socks, they both fit well but they just don't look right. If it’s a driver, use what you got. __________________ "If I asked people what they wanted they would have said faster horses." -Henry Ford "Primitive technology is not a design flaw" 1928 Ford Model A Roadster Pickup 1930 Gordon Smith Air Compressor 1941 Willy's Pickup 1960 Thunderbird-For Sale 1964 Buick Riviera 2x4 425 1965 Pontiac GTO, 455 Super Duty 2004 Dodge Ram SRT-10, V-10 Viper 1977 Charger Jet Boat,460 Ford,Jacuzzi Jet Front Engine Nostalgia Dragster,Supercharged 296 "Fullrace Flathead" Ford Engine Build up on DVD ask Last edited by Fullraceflathead; 12-05-2022 at 10:35 AM.

12-06-2022, 06:57 PM	#3
Gary WA Senior Member Join Date: May 2010 Location: Clinton,WA/Whidbey Island Posts: 4,104	Re: Zenith to Holley mismatch You can use any top or bottoms, except for side bowl-any bottom can be used,or double venturi bottom can be used with any zenith top- as long as not worried about point judging. __________________ www.whidbeymodelaclub.com Last edited by Gary WA; 12-30-2023 at 02:36 PM.

12-06-2022, 07:52 PM	#4
CA Victoria Senior Member Join Date: Feb 2011 Posts: 2,113	Re: Zenith to Holley mismatch About half of the floats I have seen have some sort of deformity. This could affect the fuel level in the bowl. After minor corrections use the clear sight tube that screws into the lower plug below the main jet to get an accurate read on the fuel level in the bowl. __________________ Tim Downtown, Ca

12-06-2022, 09:58 PM	#5
Joe K Senior Member Join Date: Jul 2010 Location: Cow Hampshire Posts: 4,188	Re: Zenith to Holley mismatch You can check the float for a hole by submerging the float in a pot of boiling water. The water heats up the air within the float and a leak will be immediately apparent by the trail of bubbles. Joe K __________________ Shudda kept the horse.

12-07-2022, 06:32 PM	#6
Gary WA Senior Member Join Date: May 2010 Location: Clinton,WA/Whidbey Island Posts: 4,104	Re: Zenith to Holley mismatch Sponsored Links (Register now to hide all advertisements) Site Index (Model-A.org)check jets for proper length and dished on ends,flow test if you can. and ensure they are tight with one gasket-none on idle jet, file and clean up both surfaces for flatness. __________________ www.whidbeymodelaclub.com Last edited by Gary WA; 12-08-2022 at 06:12 PM.

12-08-2022, 04:49 PM	#7
Ed in Maine Senior Member Join Date: May 2010 Location: Washington Cty., ME or Flagler Cty., FL Posts: 1,106	Re: Zenith to Holley mismatch I recently worked on a carb for a club member that was leaking. I thought that this carb may have been put together with other tops or bottoms. What was a problem is that there was no 3/32 vent hole in the lower casting at the top of the bowl. The vent hole in the upper casting was plugged with dirt. When we were testing float level, we saw the strangest thing. As the gas filled the bowl we had two streams of gas suddenly come up out of the upper casting. Of course we had gas going all over the bench! It definitely was a candidate for complete rebuild. Ed

12-10-2022, 08:28 AM	#8
cars2cool Senior Member Join Date: Jun 2010 Location: Sioux City Iowa Posts: 196	Re: Zenith to Holley mismatch Thanks Ed, I double checked the castings after reading this. I ran a piece of tag wire through the upper vent hole and flushed with WD40. Nothing unusual found, no debris.

12-10-2022, 12:59 PM	#9
CA Victoria Senior Member Join Date: Feb 2011 Posts: 2,113	Re: Zenith to Holley mismatch Great suggestion Ed. I have a couple of spare tops to try it on. I think I will pre drill the plugs to allow more contact with the brass. __________________ Tim Downtown, Ca