Webers

[warner53]

Hi,

Thanks in advance.

Can any one explain the differences in the various Weber 40"s.

Ie: IDA, IDAP, IDS, IDT?

What else should I be thinking about for a conversion to Webers? What is a good price for a used set?


Warner

[jwetering]

There's no indication in the weber book I have (tomlinson) what the various nomenclature means. But given that weber is an old school italian compay, the letters probably stand for words which don't translate into english withthe same letters anyway. Things like downdraft, sidedraft, autochoke, secondary venturi design, single throat, double throat, triplle throat, perhaps somone more knowledgable will chime in.

I do know however, that the 40 IDA were standard issue on the 911 in the late 60's to early 70's, and these (the IDA that is) are the "only" carburetors that will fit the standard manifold. Of course a 46 IDA will fit, and there were Zenith and Solex carburetors made that are visually and physically similar to the 40 IDA, and of course there's PMO now which is a (much improved) modern copy of the 40 IDA. You'd have to get really creative with hand built manifolds though to make an IDF or DCNF fit a 911 engine I'd think.

Interestingly, leafing through Tomlinson just now I see that the 48 IDA carburetor is in fact a 2- barrel. Perhaps the letters are random? Another interesting note....the 40 IDA was standard equipment on the first Ferrari 365 BB cars...this had a flat-12 engine. Of course the Ferrari used four of these carbs instead of two like the Porsche. Gotta say that the 365BB is one of my favourites, it was apparantly quite a few hundred pounds lighter than the 512 BB that came later. But I digress...

[warner53]

bump

[jwetering]

Actually Warner - there's heaps and heaps of posts that discuss webers and what works and what doesn't. A search for *weber* will give you a weeks worth of reading. I think a set of weber 40 IDA which don't leak along the throttle shaft are worth $1000. Compare a set of PMO which cost aroung $3500.

As you will find out, webers alone don't add much except a little snappier throttle resonse. What you are getting however is the opportunity to run a much more aggressive cam, which will make more power. You don't say what type of car you have, but assuming it's a CIS based car, it will have fairly mild cams since CIS fuel injection systems get upset by aggressive cams which tend to pulse back through the intake.

You'll need to swap out your fuel pump for a low pressure one in any event, and you'll need some fuel rails and a pressure control unit. PMO sells really nice stuff for not much money at all. If you do switch cams you'd be well advised to install different pistons as well. I understand CIS pistons work best with CIS systems.

I have a 3.0 Litre engine with JE 9.5:1 pistons, and webcam 120/104 cams. It makes 240 hp or so. The stock 3.0L itre with CIS makes 190 hp.

Search and ye shall learn.

[warner53]

I have a 71 2.2T motor that I want to build up.

I have leads to various weber 40's but want to understand the different nomenclature on the 40's, ie what is the difference between IDA and IDAP?

Some of you racers must know a source of this information.

Thanks Warner

[randywebb]

"You'll need to swap out your fuel pump for a low pressure one ..."

- better & cheaper to add a PMO pressure regulator and keep the quality Bosch pump.

[andrew15]

3 Barrel Webers:
IDA - Standard carb - found on early 911 models after the Solex carbs were replaced
IDT - Slightly different idle mixture screw - Found on some early 911T applications
IDS - High speed enrichment circut - found on early 911S models

Basically, with rejetting, any of these will fit a wide variety of engines.

IDAP - not sure

Regards,
Andrew M

[warner53]

Hi,

Thanks,

So basically any 40 weber three bbl can work on a 911?


Warner