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q-jet adjust

Old 08-12-2018, 09:28 AM
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vince vette 2
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A secondary issue (no pun intended) on my carb adjust as I'm about to pull the rear-end and rear suspension out of my car (again). But in my test drives whenever I start the car it starts fine, goes on the high idle OK, and then kicks down after after a few seconds when I kick the pedal. This is where the problem starts. The idle at this point in neutral is quite low. So low the car can't idle in drive with the brake on unless I ride the throttle. The simple answer would seem to be turn up the idle screw on the left side of the carb. The problem is that after 3 or 4 minutes of running the idle comes up 200 to 300 rpm. So if I turn up the idle to run OK when the engine first starts and comes off the high idle then 3 or 4 minutes later it will be idling around 900 rpm with in drive with the brake on - much too high.

For history of the carb - it is original, it was rebuilt by Cliff Ruggles during which it was set up for the stock original L82 that's in the car. I did adjust the idle mixture when I reinstalled it. I did this with a vacuum gage and went back and forth between the two screws to keep them close to each other. Ultimately they landed at about 4 1/4 turns each.

So, guidance on what to look for as possible causes. And I'd be interested in knowing what in the car causes the noticeable increase in rpm after a few minutes of warming up. Clearing there's something kicking in at that point, I assume it's driven by a temperature.
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Old 08-13-2018, 10:46 AM
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Rescue Rogers
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I think its a choke issue. It sounds like its adjusted that it drops the high idle to soon but is holding the choke flap shut longer. I would contact Lars and ask him.He knows these carbs like he invented them.
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Old 08-13-2018, 12:32 PM
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lars
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Your choke should not be coming off fast idle after only a few seconds. You need to adjust your choke and choke pulloff correctly. Complete instructions for doing this in my Q-Jet paper, available by e-mail request.

Lars
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Old 08-13-2018, 06:11 PM
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vince vette 2
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Originally Posted by lars View Post
Your choke should not be coming off fast idle after only a few seconds. You need to adjust your choke and choke pulloff correctly. Complete instructions for doing this in my Q-Jet paper, available by e-mail request.

Lars
[email protected]
Thanks Lars. I'll drop a note via email.
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