Weber 40IDP13C1 for 2.4T

[marlinaness]

I am relatively new to the forum, but have seen how great folks are here.

I recently picked up a 70 911T with 2.4T with webers. Bought on ebay, popped, snapped, and appeared to run way too rich (discovered 7 psi into carbs, so needs fuel pressure regulator). Carbs had issues, so I am rebuilding. I discovered they are 40IDP13C1s with 27 venturies, mixture of 105 and 125 main jets, 177 air correction jets, 52 idle jets, and mixture of F26 and F1 emulsion tubes. These were probably optimized for a 2.0.

I had great experience and 8 years of no issues with a 1971 911T with weber 40IDA3Cs on a 2.2 S Cam, E piston car running the autobahns of Germany, so I am very partial to them.

Since I don't enough about the different types of Webers, a few questions for the experts:

a) are the IDPs ok to use with this 2.4T or should I just let them go? Is there a big difference in the carbs. The two Weber books I have don't go into details on this.
b) If I should keep them, should I buy the recommended 40IDA3C internals e.g. 30 venturi, 130 mains, 180 air correction, 55-60 idle jet, F1 emulsion or something else?
c) if they are not sufficient, any recommendations on webers vs PMOs vs EFI.

thanks in advance for any feedback whatsoever.
regards marlin

[911pcars]

"a) are the IDPs ok to use with this 2.4T or should I just let them go? Is there a big difference in the carbs. The two Weber books I have don't go into details on this."

They're fine. The main difference between the Webers for a particular model is the jetting setup. The IDS models (911S) have a high speed enrichment circuit that's not really necessary.

"b) If I should keep them, should I buy the recommended 40IDA3C internals e.g. 30 venturi, 130 mains, 180 air correction, 55-60 idle jet, F1 emulsion or something else?"

Not sure these are the latest charts:



"c) if they are not sufficient, any recommendations on webers vs PMOs vs EFI."

Even if the throttle shafts are worn (eventually), the rebuild cost should be a lot less than the price of a new set of PMOs (nice as they are).

Sherwood

[marlinaness]

Sherwood,
wow.
thank you very much. this is great. I took apart and cleaned everything and found plenty of dirt, varnish, etc. I also read them better and they are 40IDTP13C. I can find no reference to these anywhere, but the gaskets look correct. So I will go with the newer internals for now unless these have some very specific niche use that might make them extra valuable and I could sell them and get plenty of money for PMOs.
thanks again
marlin

[rallye911]

Marlin,
Haynes manual, page 50 in my copy, shows settings for 40IDTP13C, and notes that they were used on some Euro 911T models from 1969-71.

Regards

Angus

[911pcars]

I believe the correct designation is 40ITP3CI. Also used on '69 T and 914-6 models (same engine). They had smallish main jet and idle jets for emission regs. Also, shorter and more pointed idle mixture screws for limited adjustment range. Otherwise, they're basically the same as 40IDA versions.

Sherwood
http://members.rennlist.org/911pcars

[rallye911]

Sherwood,
Haynes manual shows both designations, 40IDTP3C and 40IDTP13C, with different jet settings. C and C1 are left and right carburetors (control linkage at opposite ends).

Regards

Angus

[shbop]

) If I should keep them, should I buy the recommended 40IDA3C internals e.g. 30 venturi, 130 mains, 180 air correction, 55-60 idle jet, F1 emulsion or something else?


The spec sheet I have shows everything you mention, above, except for the emulsion tubes. I show an F26.

[marlinaness]

very good, thanks again for the info and confirming. I have heard the 27s will work, but I will probably just get the recommended parts rather than wasting my time hoping they will work.
sincerely
regards
marlin