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05-20-2024, 09:53 PM | #1 |
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Join Date: Feb 2011
Location: Lincoln, Nebraska
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Weber carburetor & fuel pressure question.
I'm starting to work on a car for a club member that has a Weber two barrel carburetor. It has a Holley inline fuel pump that from what I can find operates between 1.5 psi and 4 psi.
Is this range of pressure okay for the carburetor or would putting a pressure regulator be necessary? The car isn't wanting to run well at low rpms. While taking off the carb and manifolds I found some pooling of fuel in the bottom of the two intake ports that is concerning. I also found that all four of the exhaust ports have equal signs of exhaust gases leaking at the bottom of each port. I will be checking the flatness of the manifold surfaces.
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Dave / Lincoln Nebraska |
05-20-2024, 10:04 PM | #2 |
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Location: Camarillo, Ca
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Re: Weber carburetor & fuel pressure question.
My weber runs fine at 3.0 PSI. I use an Edelbrock pump. I would think that 1.5 to 4.0 would be fine. Do you have a fuel pressure gauge? If not, you might want to install one.
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05-20-2024, 10:38 PM | #3 |
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Re: Weber carburetor & fuel pressure question.
I think your problems are more to do with the leaking manifold gasket than the fuel pump.
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05-21-2024, 07:09 AM | #4 |
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Location: Western North Carolina
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Re: Weber carburetor & fuel pressure question.
First fix any intake and exhaust leaks. Use the copper clad gaskets on the manifold. Re toque the nuts after the initial run and then at about 100 miles.
If you still are not getting a good response from the Weber, purchase some larger idle and main jets to try and get a new float valve. The float valve with the smaller hole works just as well for the Model A and has less tendency to leak. Use a larger main jet on the secondary throat because this throat is used for power. Use the minimum main jet that will provide good running on the primary throat because this will lead to better fuel mileage. Adjusting the idle a tad rich will help with the lower rpm. That pressure range for the fuel pump is just fine for the Weber. In hot weather the carburetor will boil out some fuel when it is parked after a drive. The hand throttle should be used to open it up a bit before starting and the choke should not be used. Do not use the foot throttle as this can pump more gas into the intake because of the acceleration pump.
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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. Last edited by nkaminar; 05-21-2024 at 08:04 PM. |
05-21-2024, 06:01 PM | #5 |
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Join Date: Feb 2011
Location: Lincoln, Nebraska
Posts: 1,927
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Re: Weber carburetor & fuel pressure question.
Thanks for the confirmation that the fuel pump has the right pressure range.
Found the problem with the even exhaust leak across the bottom of all four exhaust ports. The upper bolt for the oil return pipe was contacting the backside of the exhaust manifold tipping it out slightly not allowing good contact with the block. I've ordered the gaskets and diaphragms for a rebuild of the carburetor.
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05-21-2024, 08:07 PM | #6 |
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Re: Weber carburetor & fuel pressure question.
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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. |
05-21-2024, 08:14 PM | #7 | |
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Re: Weber carburetor & fuel pressure question.
Quote:
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05-22-2024, 05:14 AM | #8 |
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Join Date: Jan 2012
Location: Western North Carolina
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Re: Weber carburetor & fuel pressure question.
Burtz block, cam, head, flywheel, overdrive. Runs great. I accidentally got it up to 73 one time and it still had more to go. Good tires, brakes, steering to match. I try to keep it between 60 and 65 on the interstate but like to drive it at 45 to 55 on back roads.
"Took my foot off the gas, and man alive, I shoved it down into overdrive." https://www.youtube.com/watch?v=868DSi85odQ
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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. Last edited by nkaminar; 05-22-2024 at 06:54 AM. |
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