Carb jargon...
Tom Beavington
Could someone shed light as to what all the letters after the throat size
stand for...you know... IDF's, IDA's, ICT's etc etc. What are the
advantages and disadvantages to each type.
Cheers
Tom Beavington
Gregg Holmes
Shad Laws
follow a definate rhyme and reason... :-) For more confusion, discover the
reasoning behind the emulsion tube F-numbers (answer: none! F1 was made
before F2, etc. - that's it!). Weber is trying to confuse us.
For example, a DCNF carburetor is a DCN installed on a Ferrari and a DCNL is
a DCN installed on a Lamborghini... but this meaning of F isn't the same on
a DFAV/DFEV :-)
DC usually means dual throat. But, then again, D alone often means dual
throat, except for cases like the IDA3C... O means sidedraft - I don't think
there's any violation there.
There are tables of all Weber carbs and what they are. For VW use, I
*think* these are all the ones you'll come across. The numbers refer to the
throat size in mm of the carb. Not all throat sizes can be compared
linearly, i.e. a 48 IDA isn't the same as an 48 IDF. Here goes...
34 ICT - downdraft, one throat. Commonly used as a dual one-throat setup.
A good setup. They are very similar to the Solex Kadrons (they have 40mm
throats).
40, 44, 48 IDF - downdraft, two throats, float bowl located in between the
throats. Commonly used in pairs for an IR (independent runner, i.e. one
throat per cylinder) setup on a VW or as a single, center-mounted setup (one
throat for each head). This is a GREAT carburetor to run on a VW. Even
with a pair of them you can get a smooth-running engine - very clean.
Dellorto liked this setup and made their DRLAs nearly identical to the IDFs.
48 IDA - downdraft, two throats, float bowl located in between the throats,
race setup. This carb is for serious power! As is, they only come in 48
and have a very poor progressive circuit. However, they are often modified
to be larger (51.5 I think) and sometimes are properly modified to have a
better progressive circuit. Gene Berg made some new castings for an
IDA-style carb that has 58mm throats! As you can see, these carbs are
strictly for race applications. You *can* get a set to run pretty well for
street use, but personally I'd just save my time and money and go for some
IDFs unless you really do want an all-out race carb setup. BTW, if you see
Porsche people talking about IDAs, they are actually referring to IDA3C
carbs that have three throats ("C" usually means throat...).
36, 40, 42, 44 DCN/DCNF/DCNL - downdraft, two throats, float bowl located on
the side of the two throats. These aren't as common for VWs, mainly because
they aren't as available. However, if properly setup, they can be quite
nice, especially since their size is smaller than that of the IDFs - a plus
for small engine compartments :-).
40, 42, 45, 48, 50 DCO/DCOE - sidedraft, two throats, float bowl located on
top/in between the two throats. These are the classic sidedraft Weber
carbs. They aren't too common in VW use :-) However, I've seen some
off-road turbo applications that use a DCOE quite well. Dellorto copied
this design for their DHLA carbs.
32/36 DGV/DFAV/DFEV/DGAV/DGEV - these are all progressive two-throat carbs
with the float bowl to the side of the throats. I *think* the
differentiation between the F and G is the determination of which throat is
which (i.e. F is vice-versa of G). For VWs, get the DFEV carburetors.
These are cheaper than their high-performance brothers but still offer a
good power increase over stock. If you really have a tight budget, they'd
be a good choice. If you have more money available to you, then do the job
once and go for some dual 2 throat carbs (or one throat if you have
singleport heads). Most likely, you'll decide to boost the power to these
later on the future anyway... :-)
Most of these carbs have the potential of running quite well on your engine.
None of them have any potential of running correctly if you don't jet them
properly. Whatever you do, don't take the carb out of the box and think its
good enough - it probably isn't.
For a great source of advice on which carb is best for what application, go
to www.aircooled.net and look at their tech articles. If you're looking to
buy some carbs, they have them on sale right now... John C. would help you
out with your jetting, too, to get your carbs right where they should be.
Best of luck,
Shad
Tom Beavington <smoo...@globalnet.co.uk> wrote in message
news:8da86a$s3j$1...@gxsn.com...