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05-18-2023, 08:33 PM | #1 |
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Location: Aurora, CO
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Rough Idle When Pointed Uphill
Hi all. I'm scratching my head a little with this one. I have a good Zenith 2 on my car that runs great down the road with good response and power. The idle get's a little odd under certain circumstances. It idles great when the car is on a flat surface or if the car is pointed downhill, but it idles rough when the car is pointed uphill (i.e. on my driveway with the front of the car point uphill). I'm a little confused by this one. Thoughts??
Thanks in advance! Matt
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1929 Briggs Fordor 165B 1930 Deluxe Coupe 1966 Mustang 2015 Ford Focus ST |
05-18-2023, 09:30 PM | #2 |
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Re: Rough Idle When Pointed Uphill
Must be the float setting.
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05-18-2023, 09:53 PM | #3 |
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Re: Rough Idle When Pointed Uphill
That would make sense, except the gas would slosh to the back of the bowl where the jets/passages are, right? Not starving the carb of fuel?
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1929 Briggs Fordor 165B 1930 Deluxe Coupe 1966 Mustang 2015 Ford Focus ST |
05-18-2023, 10:05 PM | #4 |
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Re: Rough Idle When Pointed Uphill
Not enough fuel flowing from the tank to the carb when you ask it to over come gravity by pointing the flow path up hill.
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05-18-2023, 10:59 PM | #5 |
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Re: Rough Idle When Pointed Uphill
There would be plenty of gravity in a model A, but too little or too much gas can cause rough idling.
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05-19-2023, 06:49 AM | #6 |
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Re: Rough Idle When Pointed Uphill
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A is for apple, green as the sky. Step on the gas, for tomorrow I die. Forget the brakes, they really don't work. The clutch always sticks, and starts with a jerk. My car grows red hair, and flies through the air. Driving's a blast, a blast from the past. |
05-19-2023, 08:16 AM | #7 |
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Re: Rough Idle When Pointed Uphill
How steep? And did you tighten the GAV a bit?
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05-19-2023, 08:40 AM | #8 |
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Re: Rough Idle When Pointed Uphill
I tend to agree with bruceincam regarding fuel flow from the tank. Have you tried testing in uphill position with a full tank? If it improves the smoothness at idle then you might have a restriction in your fuel tank. A change in head pressure might affect fuel flow when in the uphill position with a low level of fuel.
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05-19-2023, 10:36 AM | #9 |
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Re: Rough Idle When Pointed Uphill
You'd think it wouldn't run well down the road if there was a fuel flow issue, but it runs great down the road with good power.
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1929 Briggs Fordor 165B 1930 Deluxe Coupe 1966 Mustang 2015 Ford Focus ST |
05-19-2023, 10:37 AM | #10 |
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Re: Rough Idle When Pointed Uphill
Typical driveway steepness of maybe 4-5% grade, so not that steep.
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1929 Briggs Fordor 165B 1930 Deluxe Coupe 1966 Mustang 2015 Ford Focus ST |
05-19-2023, 10:38 AM | #11 | |
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Re: Rough Idle When Pointed Uphill
It has 3/4 of a tank right now. It runs great down the road with good power, which you wouldn't expect if there was a fuel flow issue.
Quote:
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05-19-2023, 12:19 PM | #12 |
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Re: Rough Idle When Pointed Uphill
Might change the float. A worn spot above the float valve??
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05-19-2023, 01:57 PM | #13 |
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Re: Rough Idle When Pointed Uphill
That's a thought. I've got a bunch of floats, so I'll try that. Thanks!
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