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Registered
Join Date: Mar 2003
Location: Palm Beach Gardens, FL
Posts: 3,110
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Webber Jetting Question
Guys,
I recently shipped my 67 911 with fresh 2.0S rebuilt engine and carbs to Switzerland from the states. The carbs ran well in the USA, but now are running rich since arriving here in Europe. The car idles fine, but is slow to respond at lower rev`s and seems sluggish up until around 6,000 rpms. Above 6,500 they really jump and the car accelrates great thru redline at 7,300. I have heard that because of the altitude change carbs that are jetted for lower altitudes will run rich. A friend suggested that because of the altitude I should be running smaller main jets. I should change my main jets from 155 to something smaller like 130. Is that correct? Any thoughts and/or ideas would be appreciated? |
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06-11-2004, 04:59 AM
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no expert but that seems like to big a jump to me. hopefully steve W will chime in. he'll know.
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-Jay '74 Mexico Blue 911 3.0 EFI (Fast and Loud) '70 914/6 Race Car (Faster and Louder) '71 73RSR tribute vintage race car 3.0 '68 SWB 911T "RENNRAT" 2.8 twin plug/915 gearbox '81 Magenta IROC clone in progress 3.6 varioram/G50 |
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06-11-2004, 05:38 AM
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Join Date: Dec 1999
Location: TX USA
Posts: 9,804
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I think 145s would work fine.
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Warren Hall, Jr. 1973 911S Targa ... 'Annie' 1968 340S Barracuda ... 'Rolling Thunder' |
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06-11-2004, 05:51 AM
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Stay away from my Member
Join Date: Aug 1999
Location: Agoura, CA
Posts: 5,773
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155 mains are pretty big for a 2.0S; 130's are stock...so you are correct that the car must be quite rich on the main circuit with the thinner air.
What are the idle jets? They would have a big impact in the off-the-line and midrange responsiveness. Also does it have really large main venturis/chokes? With 155 mains it may have been set up with 34 (or even bigger) venturis which would also impact the snappiness at lower revs.
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Chris C. 1973 914 "R" (914-6) | track toy 2009 911 Turbo 6-speed (997.1TT) | street weapon 2021 Tesla Model 3 Performance | daily driver 2001 F150 Supercrew 4x4 | hauler |
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06-11-2004, 08:10 PM
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Registered
Join Date: Mar 2003
Location: Palm Beach Gardens, FL
Posts: 3,110
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Thanks for the replies so far.
My venturis are 32`s. As for the idle jets, it`s been a while but I am pretty sure that the idle jets on the 2.0S were suppossed to be 55`s. I believe my idle jets are currently 60`s and my main jets are 155`s. So if I simply switch out my idle jets to 55`s and my main jets to 145`s, would I have to do any re-tuning or other adjustments? Seems pretty simple? Where could a buy just a set of Webber carb jets - PMO, or is there any other place? |
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06-13-2004, 03:05 AM
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Stay away from my Member
Join Date: Aug 1999
Location: Agoura, CA
Posts: 5,773
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PMO does have the jets; and Richard could also help with jetting and tuning advice.
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Chris C. 1973 914 "R" (914-6) | track toy 2009 911 Turbo 6-speed (997.1TT) | street weapon 2021 Tesla Model 3 Performance | daily driver 2001 F150 Supercrew 4x4 | hauler |
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06-13-2004, 09:35 PM
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