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Registered
Join Date: Aug 2004
Location: Houston, TX
Posts: 895
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Weber Air Correction Screws
Gents
Please take the time to read if your Weber knowledgeable. Background: 2.4, E cams, 9.5 CR, Crane XR3000 ignition, B7ES plugs, Jacobs wires, PS-91 coil, Webers, .60 idle, 130 mains, 34mm venturies, professionally rebuilt by Bieker Engineering, dynoed for jetting on chassis dyno, A/F set at 13:1. I have consistently been getting around 13 MPG (half and half mixture of roadways). additionally, there is always wet black soot gathered on the rear valence and the engine fan from the exhaust. I recently found the following instructions on the PMO website (pmocarb.com). i took particular note of the last two sentences: After you have the idle mixture initially adjusted, you can bring out your STE and adjust the Air Screws. Find the barrel which is pulling the most vacuum, then adjust the other cylinders to an equal vacuum using the Air Screws. The cylinder which is pulling the most vacuum you leave alone. Unlock the nuts before adjusting the Air Screws. Tighten them by hand as you go along; when you’re finished you can lightly tighten them using the 8 mm wrench while holding the screw stationary with the stubby screwdriver. Remember that the Air Screws can be used to lean out idle or cruise by adjusting them one or two turns out initially. The advantage to this method is that it doesn’t effect transition like closing the Mixture Screws does. So.... I tried it. i went with one additional turn open, re-synched, re-mixed, re-idled... the results... stop and go traffic during the drive from San Diego to LA... 17 MPG. on the return trip without traffic, averaging 3500 RPM... 20.5 MPG!! i don't have any popping that i can hear and the exhaust has cleaned up. so i'm a little concerned that everything is way too lean now. is there a way i can check this without buying an LM-1 or spending some bucks on dyno time. maybe run it at a smog station or something... maybe a hand held gas analyzer... has anyone tried this air correction adjustment? what were your results? thanks for your help and time with this. matt
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Matt 72 911T Targa - Sold Hang up the cell phone. Put down the Latte. Ignore the kids in the back seat. Use your blinker when you want to change lanes. AND DRIVE YOUR Fu@#!NG CAR!! |
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11-30-2004, 03:11 PM
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Registered
Join Date: Jul 2001
Location: Springfield, MO
Posts: 1,422
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3500 rpm, in a 2.4 car (72-73) would be 70-73 mph?
Go to the 4 lane, run about your normal rpm (3000-3500) and pull off at a rest stop. Pull a plug from each bank and take a look at it. Match the color to a plug color chart. This will tell you alot. David Duffield |
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11-30-2004, 03:27 PM
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Join Date: Aug 2004
Location: Houston, TX
Posts: 895
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yes, about 70 mph.
i've thought about pulling the plugs, too. is the color chart still accurate for an aircooled engine?
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Matt 72 911T Targa - Sold Hang up the cell phone. Put down the Latte. Ignore the kids in the back seat. Use your blinker when you want to change lanes. AND DRIVE YOUR Fu@#!NG CAR!! |
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11-30-2004, 05:11 PM
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Registered
Join Date: Mar 2001
Location: Marysville Wa.
Posts: 22,435
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the crappy gas these days makes plugs run darker than the old days. tan to dark brown is ok. don't really want to see white or black.
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https://www.instagram.com/johnwalker8704 8009 103rd pl ne Marysville Wa 98270 206 637 4071 |
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11-30-2004, 07:06 PM
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Registered
Join Date: Aug 2004
Location: Houston, TX
Posts: 895
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pulled the plugs. had varying colors from perfect to wet. leaned out the #1 (wet mixture). here's some pics. suggestions welcome.
#1 cylinder  #3 and 6 cylinders  #2, 4 and 5 cylinders  thanks matt
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Matt 72 911T Targa - Sold Hang up the cell phone. Put down the Latte. Ignore the kids in the back seat. Use your blinker when you want to change lanes. AND DRIVE YOUR Fu@#!NG CAR!! |
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12-02-2004, 10:32 AM
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Registered
Join Date: Jul 2001
Location: Springfield, MO
Posts: 1,422
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I like 2,4 and 5. However, my plugs look more like #1. I really don't know, ask John Walker.
David Duffield |
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12-02-2004, 03:19 PM
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