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Old 07-17-2012, 10:04 AM   #1
Join Date: Jul 2012
Posts: 5

I just join!! I recently purchase a 1989 Jeep YJ and replaced the old 258 with a new 258 rebuilt motor. The old motor had a Motorcraft D30F EA carburetor. I currently use the this carburetor on the new motor. It's OK, but it's a real gas hog. Anyway I am trying figure how to change or replace my Motorcraft D30F EA carburetor on my 1989 Jeep YJ. What carburetor would be the most gas friendly to use?

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Old 07-17-2012, 10:20 AM   #2
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Join Date: Feb 2012
Location: Raleigh, NC
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My carb list doesn't go that 'modern', but I think that's off an 83 302 ford truck.....if it is a 1.08 venturi model (cast into side of carb by throttle linkage), you can tune it just fine for milage. Bigger models (1.21, 1.23) aren't so good.

A good base line for milage (at sea level) is 47 main jets, fuel level 7/16" top of float to rim of carb body & accelerator pump rod in the #3 hole. Assuming you don't have an internal leak, of course. Rebuild kits cost 13 bucks & are super easy to do. Distributor timing makes a big difference, too.

I have the same carb on my 258 and get 16-17 in town & 21 highway. I drive like a granny, tho.

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Old 07-17-2012, 10:38 PM   #3
Join Date: Jul 2012
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Thanks for the information. I do have 1.08 Venturi model. I live in Helena, Montana. So I assume I will need to adjust the Carburetor for altitude (4000) or maybe a different jet? It idles rough, thinking it might have a air leak someplace between the plate and gasket. So I do have the best carburetor.
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Old 07-17-2012, 10:55 PM   #4
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Of that type, yes. It is a good carb
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Old 07-18-2012, 10:26 AM   #5
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That is still a good baseline to start from at your altitude (47 jets are pretty lean at sea level). Do the rebuild w/ a good overnight soak in quality carb cleaner. There are several good write ups online that will help immensely.

Do yourself a favor & mark where your choke housing is before you dissasemble it. A mark on both the carb body/housing and the movable cover. Saves a bit if readjustment later.

The kit will come w/ two base gaskets.....use both under the carb, paying close attention to be sure there are no vacuum leaks.. Make sure the one under the adapter is still good, also.

Set up correctly, on a tight motor..... that carb will start immediately, idle smoothly at 650 RPM, take decent inclines w/out stalling & pull down at least high teens MPG on a stock-tired jeep.
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