Info wanted on Weber 40 (really 44) IDF 13/15 carbs?!

[Brad K]

UPDATE - THESE WERE 44IDF's

hey guys - i have just acquired a rebuilt engine, which has webers - the engine is now delivered in the crate, and it won't come out for a week or so - in the meantime, i pulled the top's off of the webers to get the venturi and jet sizes - the top cover had built in velocity stacks/air horns, which i had not seen before - i did not get any numbers off of the webers (I will post that info soon - i hope), but the webers say bologna on the bottoms

i have done some internet research and it looks like these are weber 40IDF 13/15's, as used on twin cam fiat 124's (schematic below)

does anyone have any experience with these particular webers on a 356? any suggestions? any need for velocity stacks? (please no get rid of the webers suggestions - i would have posted this on the main talk forum for that!)

i intend in putting some rebuilt correct solex's in the future, but for now, i'm curious about these webers

thanks, brad in sea

[Greg Banfill]

In case you missed my email(s) you adapter plates will be on the way to you as soon as I get back to Nor Cal Tuesday.
As for the IDF's, I don't know that I had the same Fiat ones you have, but I have had many with the stack built into the top plate. Nothing else was noticeably different about them.

[Brad K]

thanks greg (i also got your last email - thanks)

i have been doing some late night sleuthing/comparing with some not great photos i have of my weber's, and I found some fiat 124 weber 40 IDF 13/15 threads online (photo's from fiat 124 thread posted below) - it looks like the top plate with the built in air horns is the only part on my weber's similar with the more unusual parts on the 13/15's

- i have attached photos of the differences in the 13/15's from the regular 40 IDF's we see in our 356/912's - some of these extra parts are for vacuum (#2), fuel supply back to the tank (#3), and cold start choke (#1) - none of these seem to be on my webers (from what i can see for now)

thanks again - brad

[C J Murray]

#1 is the cold start lever to flood the carbs. They can remain unused but make sure that the system does not leak raw fuel into the engine.

#2 is a vacuum port that the Fiats must need for something. Plug it.

#3 looks like another vacuum port but it seems to be entering the fuel inlet area so I am not sure but you will not need it. Plug it.

[George Bryan]

Hi Brad. It has been my experience most Weber IDF's come in the box with the choke assemblies. You remove them for 356 use and put on a flat cover plate which is a Weber part. The stacks are just an older Weber production; the type you have could sit inside the standard air cleaner housing if you cut out the center bar and did a little trimming. Most often they were just put on top of the carb and run as an open stack. Great for setting your synchrometer in to adjust your carb. I have found the shorter independent stacks to be the easiest to work with though.
Regards,
George

[Mark Sabbann]

Brad,
My car came to me with big-bore cylinders and early Webers. I think they are 40 IDF 18/19 which also have the roller lever to the accelerator pump. The 18/19 refers to the right or left side arrangement. They don't have the additional tube fitting you show, but they do have the short cylindrical intake stacks instead of the smoother bolt-on venturi type. The cold start feature has been blanked off too. Once I got them rejetted and changed to 32mm venturies they run better than ever. I think the intake manifolds are also Weber instead of adapted Zenith manifolds.

[Greg Banfill]

Both sets of Italian IDF's I have (40 and 44) have the choke on them.
The 40's have the top plate with stacks built in. Not sure how much of that is "stock" though as they have been passed around for years before I got them.

[Brad K]

thanks to all for the information - is there any need for velocity stacks, when using this integrated air horn carb top? if so, how tall? how to attach?

thanks again, brad

[John Clarke]

Hi Brad,

These IDFs are the earlier design incorperating a Cam and Roller to operate the Accelerator Pump. This was non adjustable unlike the later Weber IDF and the Solex P11-4 with the adjustable link underneath.
Years ago we ran a pair of these on a 356 and it was typical to deliver as much as 0.5cc of gas per Stroke, Way too much and causing an off Idle stumble on take off!
The Only way to reduce the output, which we did, was to reprofile the cam with a less aggresive lobe or profile. Better to Fit your Solex P11-4s or the later Weber IDFs.
Having said all this, and I've said it many times, find a Good Pair of Dellorto DRLAs.
Not a better Carb for the 356 / 912 Engine, IMHO.

Cheers

Jay

[Brad K]

hey jay cee - i also read what you stated in the late duane spencer's excellent 912 book - i just got my new engine out of the crate, and you are right - no adjustable accelerator pump - is there a way to change out the accelerator jets for a smaller ones? (sorry, if this is a dumb question - i'm just getting up to speed on webers!) - thanks, brad in seattle

[Brad K]

turns out these were 44 IDF's - soon to be on ebay!

thanks for everyone's help - brad

[Greg Banfill]

turns out these were 44 IDF's - soon to be on ebay!

thanks for everyone's help - brad

Italian or Spanish?

Let me know I like Italian Weber's

[Brad K]

hey greg - they're italian, made in bologna, with 36mm venturi's, F-11 emulsion tubes, 55 idles, 125 mains, and 200 a/c's - let me know how interested you are! brad in sea

[Richard Van]

I am in need of part # 72 - # 76 as can be seen on the attachment in the first post. Apparently a PO lost or removed them. Is there a source for these choke / cold start parts?

Regards,

Richard

[Brad K]

i would call these guys:

http://www.redlineweber.com/

http://www.pmocarb.com/

both have been very helpful for me - hope this helps - cheers - brad