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Disabling Choke on ZS carb

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Disabling Choke on ZS carb #1
dannyclarke58 Danny Clarke La Quinta, CA, USA Sign in to contact 1975 MG MGB "Lilly"	Topic Creator (OP) Apr 17, 2026 07:06 PM Joined 7 months ago 197 Posts

I converted the water choke on my Zenith Stromberg carb to manual but I'm still having issues with setting the idle on the carb and I believe the choke is part of the problem.

To disable the choke entirely, I should be able to just lock the mechanism in a completely open position right? I

f the cam isn't moving and the high idle pin is not being engaged then only the low idle adjustment screw would need to be adjusted, right?

Am I over simplifying this?

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Re: Disabling Choke on ZS carb #2
Vic92 Timothy Cook A Trenton, NJ, USA Sign in to contact 1975 MG MGB	Apr 18, 2026 07:13 AM Top Contributor Joined 9 years ago 822 Posts

Which conversion kit are you using?

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Re: Disabling Choke on ZS carb #3
psksks76 Pete Shannon burlington, NC, USA Sign in to contact 1971 MG MGB GT "SOLD" 1974 MG MGB GT 1975 Triumph TR6 "SOLD!" 1977 MG MGB MkIII "MG" & more	Apr 18, 2026 10:43 AM Top Contributor Joined 13 years ago 4,332 Posts

"To disable the choke entirely, I should be able to just lock the mechanism in a completely open position right? I

f the cam isn't moving and the high idle pin is not being engaged then only the low idle adjustment screw would need to be adjusted, right?"

Yes.
But are your symptoms a high idle that you can't get down, or is the choke mechanism still being held open, either by misadjustment or mechanically hanging up?
Reason I'm asking is that I have fought many a high idle condition not only the later z/s carbs, but the h series as well, only to realize that I had a vacuum leak somewhere.

I think your idea of removing the whole manual choke setup and just making sure the high idle pin is not engaged on any of the teeth, but is setting at rest. That will tell you what's up IMO.

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Re: Disabling Choke on ZS carb #4
Bob Allen Houston, TX, USA Sign in to contact 1978 MG MGB	Apr 18, 2026 11:09 AM Top Contributor Joined 7 years ago 2,962 Posts

You can’t just remove the choke, removing it opens airways.
This may help.

https://cdn.lotuselan.net/original/3X/9/e/9ed48036979af41048894cefa02be6920cf9f355.pdf

1978 MGB
When diagnosing issues related to running and stalling, always check to see if you have gas in the tank first.

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Re: Disabling Choke on ZS carb #5
Arizona Shorty G M P, A, Albania Sign in to contact	Apr 18, 2026 12:36 PM Joined 2 years ago 4,926 Posts

"You can’t just remove the choke, removing it opens airways."

You don't remove the choke, you remove the mechanism the moves it, which is quite easy, especially since a manual system has been installed. Then lock down the choke assembly so it can't move. I was able to do that on my original ZS without the manual conversion.

Of course, this leaves you without a choke at all.

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