Early S webers

[speedo]

Dropped the engine today in my 70 ST clone racecar. While buried in the engine compartment, I noticed that the weber IDAs actually have the S stamp on the ends of the carbs. Not what I was expecting. The engine is completely sorted, and I am reticent to replace the carbs with other IDAs I have on the shelf. Question is ...what is the value differential between non-S IDAs and S IDAs. And what is the performance differential.

Speedo

[Richard]

Speedo,

Sorry to rain on your parade. The Webers you have are early '67 911S carbs. Before they were called "IDS" carbs they were just stamped on the ends with the "S". My suggestion is to sell them to someone with an early '67S. They will be right for his car.

Sorry to be so opinionated...but don't be just be another flipper for the highest price. Let them go to a car that was born with them...and at a fair price. My 2 cents.

R.

[speedo]

Not raining on my parade at all. My question(s) related to the differences in the IDAs. I appreciate the response. I have other IDAs I can replace these with...if necessary. Yes if someone needs these carbs we can talk. But I am not immediately motivated to part with them.

Speedo

[Fritz A. Ficke]

The early 'S' carbs did not have the enrichers like the later IDS and were basically IDA's and with the same jets and chokes, IDA's will behave the same as the early 'S' carb.
I am with Richard, swap them out, run to verify, and then sell to someone who needs them to have a correct early 'S' stamp on the end of their Carbs.

[Cliff]

Did the IDS carbs have a `S` stamp?...cliff

[Fritz A. Ficke]

No, Only the S carb had that stamp on the end behind the return spring

[Cliff]

I was thinking the IDS carbs are S specific...So, the earliest IDA`s had the S stamp for the S` cars only & all the also-ran had NO `S` stamp...IDS`s NEVER HAD A `S` stamp?......cliff

[Fritz A. Ficke]

I was thinking the IDS carbs are S specific...So, the earliest IDA`s had the S stamp for the S` cars only & all the also-ran had NO `S` stamp...IDS`s NEVER HAD A `S` stamp?......cliff

The IDS weber is S specific so is the IDA with a S stamp.
When Porsche made the first 911S it was for model year 1967 and had the IDA Weber carbs with a S stamp on the end. I can only guess that was so the workers knew they were jetted for the 'S' and not put them on the Normals.
Then Porsche stated having detonation problems under WOT for long periods of time, like on the autobahn, only with the S 911's, this was because the high compression engines had piston tops that made flame "dams" while the 911 normals with IDA's did not have those pistons and the race engines which also ran IDA's and had high top high compression pistons had twin plugs, a spark plug on either side of the "dam" and did not have that problem.
Porsches band-aid fix for the 911S was having weber add a enriche nozzle to the IDA Carburetors that dumped large fuel amount of fuel in under WOT, these were called IDS, exactly the same as IDA's but with that "enricher" Some time mid year 1967 all 911S car were fitted with these and were ran on 911S cars through 1968.

[Silverbullit]

Approx. the first 500 911S engines were fitted with the "S"-stamped IDA's.

[Fritz A. Ficke]

Here is a picture of my finger on the IDS Carb's enricher nozzle.
And the IDS carb is only used on the Porsche 911S.
Porsche, 911 normals, 911R, 906 etc. all use three barrel IDA carbs as did Ferrari BB and Lamborghini Mura's used the three barrel (venturi, choke) IDA's.
The IDS was only used on the Porsche 911S. No other Porsche and no other manufacture used the IDS Weber carburetor.