Zenith internal passages

Russell Reay

Russell Reay

Well-known member
In scanning the catalogs for parts not included in the rebuild kit I saw the pkg of brass plugs for use after cleaning the internal passages. The red book says to clean them out if badly plugged, but there is no sketch of where they are and where they go. I have seen comments on this forum about the importance of cleaning them, so I might as well do so as long as the carb is under reconstruction. Is there a video or sketches that give details of these passages?
 
Russell,

Put down the carburetor and back away from your work bench. More Carburetors have been ruined by well intended novices attempting to remove those brass plugs.

Your first step is to review Tom Endy's articles (MAFCA) on rebuilding & cleaning internal passages with a simple paper clip.
 
jb-ob said:
Russell,

Put down the carburetor and back away from your work bench. More Carburetors have been ruined by well intended novices attempting to remove those brass plugs.

Your first step is to review Tom Endy's articles (MAFCA) on rebuilding & cleaning internal passages with a simple paper clip.
Click to expand...
Agree I have restored Many Zenith Model A Carbs and Never removed any Plugs!! Could destroy the carb from proper operations unless you have done before. Good luck!:)
 
I used 0.031" stainless wire rather than a paper clip, you can get it on a roll from many industrial suppliers. I followed Tom Endy's directions but found you sometimes need to grind the end of the wire to remove the wedge formed when you cut the wire with a pair of dikes (tends to make the wire hang up a bit inside the passages).
 
Never, I mean Never drill out the brass plugs on a Zenith Carburetor. Follow Tom Endys articles which are detailed and correct and blow air through the passages after and you will be in great shape.
 
Unless your carburetor has been sitting at the bottom of the fish pond for years, blowing out the passage ways with pressurized carburetor cleaner will probably work. In fact, it is often not necessary to remove anything. Just split the carburetor and start squirting.
 
nkaminar said:
Unless your carburetor has been sitting at the bottom of the fish pond for years, blowing out the passage ways with pressurized carburetor cleaner will probably work. In fact, it is often not necessary to remove anything. Just split the carburetor and start squirting.
Click to expand...

Agreed. If a passage won't pass a volume of air, then clean it out. I have only had to drill out plugs once. Brentwood Bob has probably done more carburetors than me, and he uses carb cleaner after blowing them out. That's a good idea.

This may help- https://www.youtube.com/watch?v=cR1ksgFaH90

Or maybe not.
 
Volume 9 "How to Restore Your Model A" Article "Zenith Passageway Cleaning" by Tom Endy.

Not the same article as the above Santa Anita A link, but is the same author and the same information.

Joe K
 
Update-- I finished rebuilding the Zenith according to the red book and Tom Endy's article. Attached the gas line, and she started right up. Two quick questions--the carb came with no GAV needle or choke driver. I installed the new ones, and the chrome indicator on the choke rod points to 4 o'clock when closed, compared to 11 o'clock with the previous Tillotson. Should I unscrew the GAV needle or needle housing to achieve a desired pointer setting, or just suck it up and stay aware of the setting that works? 2--the model A carbs don't have an idle adjustment screw. What is the preferred way to adjust the idle. With the GAV open a little (1/4 turn) and the throttle lever all the way up, there are not enough rpms to stay running. As I write this I recall needing to
shorten the throttle linkage when assembling the engine with the Tilly. Should I just restore some length until it sounds right?
 
Russell Reay said:
Update-- I finished rebuilding the Zenith according to the red book and Tom Endy's article. Attached the gas line, and she started right up. Two quick questions--the carb came with no GAV needle or choke driver. I installed the new ones, and the chrome indicator on the choke rod points to 4 o'clock when closed, compared to 11 o'clock with the previous Tillotson. Should I unscrew the GAV needle or needle housing to achieve a desired pointer setting, or just suck it up and stay aware of the setting that works? 2--the model A carbs don't have an idle adjustment screw. What is the preferred way to adjust the idle. With the GAV open a little (1/4 turn) and the throttle lever all the way up, there are not enough rpms to stay running. As I write this I recall needing to
shorten the throttle linkage when assembling the engine with the Tilly. Should I just restore some length until it sounds right?
Click to expand...
Leave knob where ever it is dosen't matter, Should be adjustment screw for idle on the throttle plate and the air mixture screw 1 1/2 turns out to start then fine tune it.
 
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The "Red book" (which you have) shows the idle adjusting screw on pages 1-59, 1-60 and 1-62.
 
Gary WA said:
Leave knob where ever it is dosen't matter, Should be adjustment screw for idle on the throttle plate and the air mixture screw 1 1/2 turns out to start then fine tune it.
Click to expand...

That is another part that was missing from my carb. I think I have all parts now.
 
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