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Zenith carburetor needle solder mod

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Dana

Super Moderator
Staff member
Joined
Apr 3, 2007
Messages
12,706
Location
CT, USA
I've seen some references on the web to soldering the hole in the main jet needle closed on the Zenith carburetors, but I'm not clear exactly what it accomplishes? When I disassembled and cleaned my carb, I didn't notice a hole, soldered or not, but I wasn't looking for it. My friend mentioned hard starting, and that Mory Hummel told him to solder the hole shut, but he's fuzzy on it, it was some years back.

My Mosler CB40 engine is now running fine at full throttle, but I'm not clear on the main mixture setting (I have the extension so it can be adjusted from the cockpit). The Mosler manual says to adjust it rich until it "runs rough", then adjust it lean until it runs rough, then set it 1/3 of the difference from the rich side. The thing is, it never really runs rough no matter how far I go. EGT runs 1000-1200. Does the solder mod make the needle more effective?

On the idle side, it runs unevenly, I'm always afraid it's going to quit when idling around 1000 rpm. Turning the idle mixture screw seems to have little if any effect.

Dana
 
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