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Registered
Join Date: Feb 2004
Location: Audubon,PA
Posts: 66
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WeberIDTP 40! jetting for a 2.4T
Hey Collective,
I have a 914-6 conversion. 2.4 liter. T cams. ‘67 aluminum case, 2.7 counter weighted crank and rods. (Rods balance by Ray Litz). MAHLE P&C 46mm intake and 40mm exhaust valves. Rebuilt motor has around 25K miles on it. 123Ignition distributor with OEM CDI. Carbs are 40IDTP3C. They were rebuilt for a 2.7 engine. Owner states they ran brilliantly. On my 2.4 configuration, I get a lot of popping upon initial acceleration dip in. They are nicely synchronized and it idles on cold start perfectly around 1100rpm. Wondering if the jetting/set up is too much for my 2.4. Any insight. Is there a list of what the carbs should be running for a 2.4T Thanks in advance. Cheers, Dion Last edited by DionRonio; 07-31-2023 at 01:19 PM.. |
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07-31-2023, 09:33 AM
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Registered
Join Date: Feb 2008
Posts: 1,438
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Hi Dion,
IDTP Webers will want the idle air correction jets modified to allow them be be 100, OEM size is 140 and is a change from IDA air correction jets size of 110. This change was due to emission era requirements with smaller main venturis than what were normally used by IDA Webers which were 30mm or 32mm. The IDTP Webers were developed for low HP, 2.0 liter engines used in 1969 911T and 914/6 and as such used 27mm main venturis. Installing larger main venturis will result in a lean transition issue that may be resolved by installing smaller idle air correction jets which result in an prolonged idle/progression circuit effectiveness which helps richen transition. Recommended jetting for 2.4 with T cams and IDTP Webers:
Contact me via email (on my website) regarding modification kit for idle air correction jets. Popping on tip-in: Check to see if accelerator squirter nozzles are all outputting something like 7 to 9ml per nozzle per stroke. If not then check individual nozzle tips (0.5mm diameter) for clogging and check to see if inlet check valve feeding accelerator pump is sealing properly.
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Paul Abbott Weber service specialist www.PerformanceOriented.com Last edited by 1QuickS; 08-01-2023 at 10:42 AM.. |
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08-01-2023, 08:52 AM
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Registered
Join Date: Feb 2004
Location: Audubon,PA
Posts: 66
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1QuickS: Thanks very much the detailed explanation and the specific jets/venturi list.
Had a feeling that it wasn’t going to be perfect bolt on for the 2.4 Took a gamble. It obviously is a big difference. Time to open these up then to see what was installed. I will definitely be in contact with regards to your “kit”. Again thanks so very much with the details. Cheers, Dion |
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08-01-2023, 11:27 AM
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