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72' 911S
Join Date: Feb 2007
Location: Yorkville, IL
Posts: 220
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Weber Injection Quantity
Hello -
I've read varying amounts of how much fuel should come out of the injection pump whith one full opening of teh throttle, but I've averaged it out to about 0.7 cubic centimeters (or mililiters). One of my 40IDA 3C Webers puts out that amount, but the other only puts out a maximum of about 0.35cc. I've got the adjustor nut completely tightened down too. The diaphragm is brand new, and I've checked the placement to make sure the nut is facing out. I've also checked the bushings in the throttle actuator and they are still good. No play at all. What could be the source of this issue? |
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09-24-2010, 08:03 PM
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72' 911S
Join Date: Feb 2007
Location: Yorkville, IL
Posts: 220
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Does anyone have any suggestions? I'm at a total loss right now. Is it OK to have unequal injection quantities between the two carbs? as long as I'm getting more than 0.1cc out am I OK to put them back on and see what happens?
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09-25-2010, 05:52 AM
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Registered
Join Date: Feb 2007
Location: Northeast
Posts: 463
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Check that you have equal travel on the pump levers--then you "should" have equal delivery. Tightening the adjuster nut may not have served you well.
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Mark www.exotechpower.com 1981 Targa-messed with. 91 C2 supercharged track rat Radical Prosport-irritates the GT3 guys 40 years of rebuilding services |
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09-25-2010, 06:01 AM
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Registered
Join Date: Feb 2008
Posts: 1,438
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Since the Webers have one accelerator pump to supply three cylinders there is only one adjustment to be made. From there the fuel must travel and share its delivery among the three squirters. It is most important that the bolts that secure the squirter nozzels are sealing correctly otherwise the fuel will drain back to the fuel bowl and leave you with a smaller delivery shot. These bolts have a stainless steel ball bearing that acts like a check valve, it opens when the fuel is being delivered to the squirter nozzle and shuts when the flow stops. If the interface between the stainless steel ball and the brass, hollow bolt is not clean then fuel will drain out. Also, it is good to check that there is no corrosion in the squirter nozzle. When I go through a set of Webers I resize the nozzles to assure their passageways are clean; 0.5mm for the tip and 1.5mm for the main supply hole. It is also good to blow compressed air through the fuel delivery galleries on the main throttle body to assure they ase clear of blockage as well.
Paul Abbott Performance Oriented
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Paul Abbott Weber service specialist www.PerformanceOriented.com |
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09-25-2010, 08:54 AM
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