/6 Weber Carb Questions -> Jets, Who said you can never be too rich? |
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/6 Weber Carb Questions -> Jets, Who said you can never be too rich? |
Carl |
Jun 18 2004, 04:14 PM
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#1
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Ummm ... what? Group: Members Posts: 781 Joined: 17-January 03 From: San Jose, CA Member No.: 163 Region Association: Northern California |
I'm trying to lean out a car that goes through gas like a drunken sailor. To start the process, I want to convert the carbs back to the original factory jetting then address the performance issues if that setting is too lean. Hopefully, there are authorities on carbs out there that know the answers to the following questions:
/6's came with Weber 40IDT3C's, as did the 911T (same engine). The /6 factory manual says the jetting should be: 45 idle jets 105 mains 170 air jets F1 emulsion tubes The Pat Braden book on Weber's has the following jetting for 40IDT3C's for the 911T: 50 idles 110 mains 185 airs F2 emulsion tubes Which is correct factory jetting for the 914/6? There are different jetting arrangements for 40IDA3C's. Braden says the IDA's were on the 911L engine. Were they used on other P engines? There are more references to IDA's in the printed material than IDT's. This doesn't make sense to me if they only came on 911L's because there weren't a lot of them produced vs the 911T's. What are the differences between the IDA's and IDT's? The external appearance is the same but the jetting is different for engines of the same displacement. The engine in my car has a 911T crank and case with a 2L 911E pistons, cyls & cams. The 911E was an MFI engine. I've been told there are differences between cams for MFI engines vs carbs. Is this true? If so, how are they different? Should my engine be jetted differently because of it? and finally, how come a dropped nut will always land in a location that's the most difficult to see, reach, or both? (IMG:style_emoticons/default/idea.gif) Thanks for the help. |
Carl |
Jun 18 2004, 11:27 PM
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#2
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Ummm ... what? Group: Members Posts: 781 Joined: 17-January 03 From: San Jose, CA Member No.: 163 Region Association: Northern California |
QUOTE(campbellcj @ Jun 18 2004, 08:42 PM) Definitely double check the main venturis/chokes as that makes a huge difference in how much top-end the car makes, and where it is made. IIRC the stock 914-6/2.0T had 27mm venturis. I have 32mm's in my 2.2"S/T" and full race motors usually run 34's or bigger. The wrong choice can just kill your A/F and drivability. I'm glad you made that point, Chris. The /6 manual says 27mm venturis and the Braden book says IDA's are spec'd at 30. I've had 30's in mine but have had a giant flat spot from 1500 - 3000 rpm. I changed them back to 27's but still had the dead spot. It seems to be better with the leaner jets but I've not driven it much with all the changes. I think you're right, Kim. We can change idles and mains, and, with a little work, the airs and e-tubes but venturis will take too much time. C |
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