Weber 40's or 44's

They are going On a 2056 Massive 4 C. I'd like better milage But don't want to ever run it to lean. That would not be good?

Lean is a function of jetting rather than carburetor bore size. If it's modified to make power at high RPM use the 44's, otherwise for better low end response and gas mileage use the 40's.

Barry:
Just a thought; have you considered using Dells instead of Webers? The Dells are a better carb than the Webers. The one drawback I can think of is that the Dells will almost certainly have to be bought used and rebuilt/remanufactured.

Alan, "Dels better than Webers" is a moot point; it depends on which carbs you're talking about. While 45 DRLAs are superior to 44 IDFs for some performance engines, my experience has been that 48 IDFs and IDAs are better than 48 DRLAs. I have had a pair of 44 and 48 IDFs on my 2,110 and have a pair of NOS 48 DRLA (non tri-jet) and a pair lightly used 48 DRLA (tri-jet) to try on my new 2,387.

I had four NOS Italian 48 IDAs but sold them because they are more difficult to tune and usually create clearance problems (they're bigger than 48 IDFs).


Note that Weber 48 IDFs can be fitted with fairly large venturis but 48 DRLAs are limited to a max vent size of 42mm.

George, I thinking of replacing my 40s with 48s. What's a better choice, 48 IDAs or 48IDFs. My builder thinks that IDAs would be the way to go. Any thoughts on this would be appreciated.
Ron

Ron, Weber just started manufacturing new 48 IDAs again (in Spain; the ones I sold were original Italian made carbs. The Spanish carbs seem to be working OK but check to see if they now come with the extra idle to main circuit progression holes which works better for street engines. If they don't Art Thraen (ACEVW@aol.com) can put in the extra progression ports. IDAs are racing carbs and I personally would rather use 48 IDFs or 48 DRLAs on a street engine. New 48 IDFs are available (again, made in Spain) but 48 DRLAs are hard to find in nice condition and harder to get parts for.

I have a pair of Italian 48 IDFs with 40mm venturis on my 165 to 170 BHP 2,110 and it is very smooth and tractable; it will idle down to 700 RPM (normal idle is 1,000) and have no hesitation or flat spots all the way up to 6,500 RPM. This performance is mainly a jetting and setup issue: 10.5mm "top" float level", 20mm "drop" float level, F2 emulsion tubes, 60 idle jets, 155 main jets, 165 air correction jets, 50 (or 55) pump squirters with no pump drain (50 gives better milage). Air/fuel ratio at sea level with that jetting on my engine is 12.5 to 1 (max power ratio) at steady state level cruise (may vary to 12.6 or 12.7).

Which carb's would be the most common, and avalble ? And what are the major differces between IDA's an IDF's there strenths and weaknesses.

(Message Edited 1/3/2003 9:42:26 AM)

I think that's why my builder likes the IDAs so much (idle jets on top). He drag races a Beetle, so easy access to the jets would be preferable.
Ron

Hear hear on the access to the idle jets on an IDF- on a pan based car, a stubby screwdriver is too big to fit between the back side of the driver's side carb and the fiberglass. To sync the dual 40s on my old car, I had to make one by silver brazing a screwdriver tip to a penny- and it still wasn't any fun.

Biggest difference between IDF and IDA is jet location, bore center distances (IDA is wider and taller and requires different intake manifold), the way velocity stacks are fitted, and the type of accellerator pump and pump actuation (IDA is a metal piston pump, IDF has a rubber diaphram pump). IDFs are more common and less expensive.

48 DRLA's have the same bore center distances and manifold mounting pattern as 48 IDFs but are no longer available new. IDF idle jets are in a difficult to access location while in IDA and Dellorto DRLA all jets are accessible from the top of the carburetor.

Weber IDF accel pump squirters can't be removed unless you take off the carb top; on DRLAs the pump squirters go in from the side of the carb body.

(Message Edited 1/3/2003 5:47:56 PM)

IDA's do sound better How good are the piston accerator pumps.How well do they hold up and how rebuildable are they?

Last week I spoke to Art Thraen about this same question IDA's or IDF's. He said the only reason he used IDA's was he liked the looks better . He also said the IDF's were easier to tune& make work at all RPM ranges. I mentioned auto X , road racing and hard cornering and he said stick to the IDF's.

I need to here more pros and cons .I may just wait and talk to John Connley when I order these puppies. he is familiar with Jakes builds and that might be wisest.