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Quadrajet Divorce Choke

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Old Nov 3, 2015 | 08:25 AM
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Default Quadrajet Divorce Choke

When I put the accelerator to the floor when cold, the choke sets like it should. Butterfly closed and on fast idle cam. However, a few seconds after starting, if I touch the accelerator, it cancels all that. It barely runs because it's still cold. It looks to me like it should go to the second step on the cam. Is the choke out of adjustment? How do I adjust it?
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Old Nov 3, 2015 | 08:54 AM
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What rpm is it idling at cold start before you touch the accelerator?
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Old Nov 3, 2015 | 11:35 AM
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your profile shows you have a 59 Corvette with a 350 so obviously not stock. When you set the choke by stepping on the pedal and start the car you should see at least 1,500 RPM idle speed. When you touch the gas it should drop down a few hundred rpm and when fully warm drop to normal idle. The speed adjustment screw is on the passenger side of the carburetor.

Last edited by MelWff; Nov 3, 2015 at 11:37 AM.
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Old Nov 3, 2015 | 01:56 PM
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Cold start idle is 1300 RPM, touch the pedal and it drops to 700 but engine still cold. No in- between. I adjusted that screw to obtain the 1300.
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Old Nov 3, 2015 | 07:14 PM
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I kicked the throttle and it dropped down to the second step just like its supposed to. Trouble is, the idle is the same as normal idle, 800 RPM.
If I adjust the screw for faster idle on this second step, will it be faster also on the first step?
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Old Nov 4, 2015 | 12:20 AM
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You might want to check your vacuum choke pulloff (to the right of the choke coil in the pic below). Sounds like it is pulling choke off too far.


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Old Nov 4, 2015 | 12:21 AM
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I kicked the throttle and it dropped down to the second step just like its supposed to. Trouble is, the idle is the same as normal idle, 800 RPM.
If I adjust the screw for faster idle on this second step, will it be faster also on the first step?
Yes, but 1300 on first step is too low. I have good luck with warming the engine up, manually putting it on the first step and then adjusting the high idle speed(adjustment on passenger side of carb) to 1800-2000rpm. I know, sounds kind of high but if you set it anything lower than 1500 you'll likely get a start/stall on very cold mornings.
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Old Nov 4, 2015 | 10:49 AM
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You have to adjust the choke itself before you adjust the choke idle speed. You didn't say if it's electric or via a choke rod from the choke coil on the intake manifold. If it's electric adjust the housing on the carb to remain on longer. If it's manual like the old divorced choke style from a spring, shorten the rod slightly by bending it where the two factory bends are. Measure the length before and after and use increments of about the thickness of the rod until you get it the way you like it. Once you get the choke itself adjusted then work on the idle speed.
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Old Nov 4, 2015 | 11:18 AM
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If the title of the thread is correct, it's a divorced choke, not electric. I had a similar problem and the problem was a missing piece of linkage shown by the green arrow. The orange arrow shows where the choke rod from the spring on the intake connects


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Old Nov 4, 2015 | 01:51 PM
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You simply bend [or straighten] the linkage rod from the divorced choke to the carb, as needed, to keep the choke on for a bit longer time. When adjusted, you may then need to re-adjust your 'fast idle' screw to reset the idle speed for a cold engine.

If you have installed 'block-off' plates over the intake cross-over passages, the choke system will NOT work exactly like a new car would. But, you can still set the choke system and fast-idle for BEST condition with the engine setup you now have.
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Old Nov 4, 2015 | 02:57 PM
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Originally Posted by dugsgms74
Yes, but 1300 on first step is too low. I have good luck with warming the engine up, manually putting it on the first step and then adjusting the high idle speed(adjustment on passenger side of carb) to 1800-2000rpm. I know, sounds kind of high but if you set it anything lower than 1500 you'll likely get a start/stall on very cold mornings.
This morning I set it for 1500 RPM & will see how it does tomorrow morning when it's cold. May run it up to 1600.
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Old Nov 4, 2015 | 03:01 PM
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Originally Posted by 7T1vette
You simply bend [or straighten] the linkage rod from the divorced choke to the carb, as needed, to keep the choke on for a bit longer time. When adjusted, you may then need to re-adjust your 'fast idle' screw to reset the idle speed for a cold engine.

If you have installed 'block-off' plates over the intake cross-over passages, the choke system will NOT work exactly like a new car would. But, you can still set the choke system and fast-idle for BEST condition with the engine setup you now have.
This makes the most sense. I'll try bending it a little at a time. Yes, I did install the block off plates so I know it will take longer to warm up.
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