Intake air horns for Weber IDA & IDTP the same?

[targa67]

I need some help regarding the air horns on the Weber 40 IDA 3C - 3C1 and 40 IDTP 13C - 13C1.
I only found info. on the IDA with no. 901.100.933.01 / Weber no. 52845.005, but no messurements.
Are they the same or different?
Which size do they have dia./ hight?
Seen pics. whith short and tall versions, some are zinc, nickel or have a yellow cromated finish and there seems to have been one in plastic too!

Thanks,
Steffen

[1QuickS]

All four you mentioned will fit all Weber 40IDXX3C carbs as well as Zenith 40TINs. Earliest horms were nickle plated and had thicker bases, the yellow chromated ones were used later in production (914/6?). Plastic ones were on the Zeniths (metal reinforcements used at the mounting holes) and the tall ones were sold with aftermarket Webers (blind guess) and had a little coarser spinning marks on the horns and were nickle plated.

[targa67]

Thanks Paul!

Why are there short and tall ones, different years?
What´s the size, diameter/height?

Thanks,
Steffen

[1QuickS]

50mm high for the short ones; 56mm for the tall ones. 46mm ID at the bottom and OD of the flare at the top is 65mm; all share these diametral dims.

No clue why, doubtful if any HP difference would be detected for 6mm height difference; to change HP with horn height would require quite a difference in height and would be noticible at peak RPMs.

[targa67]

Thanks again Paul!

What is the diffence between the 40 IDA 3C-3C1 and the 40 IDTP 13C-13C1?

[1QuickS]

Idle air jets on IDA are 110s and on IDTP they are 140; progression circuit drillings on IDA are different than on IDTPs. IDTPs were developed for emissions era 911 and 914/6 and have leaner progression characteristics. Check out pictures here:

Weber Carbs Technical