chokes

[347]

what will happen to my engine if i was to take out the chokes(webers 44idf)
will it idle?
will it give it more mid range?top end? none of these?

[Cobranut]

347,

What are you referrring to as "chokes"?

I didn't think Webers had choke plates, which are used to aid in cold starting.

The "twin choke" terminology used refers to them being 2 barrel or 2 venturi carburetors.

[Mike I]

347,
I've never heard of anyone trying this, but my guess is that your engine would run very, very poorly, if at all. Besides establishing the desired venturi size, chokes also serve to smooth airflow through each barrel. Removing the chokes would severely disrupt flow!
44IDF's should be fine on a street driven motor such as yours. Smaller chokes allow for better throttle response and low and mid range power. The only reason you would ever want to go to larger chokes is if you find your motor running out of air at the top end. If you spend a lot of time at the track and frequently wind your motor tight at high revs (above 6K rpm), you may want to go to larger chokes, or even to the max choke size for your carbs (presumably 44mm), but keep in mind that lower rpm performance will suffer. Also, any change in choke size will require additional changes to jets, air correctors, f-tubes, etc....very expensive.....
What size chokes are you running now? What is your established redline? What is your typical operating rpm range? If you're not happy with the way your carbs are running under present conditions and with your typical driving habits, answering questions like I've asked above should tell you what changes you need to make.

David, to answer your question, with Weber IDFs, chokes refer to variable size interchangeable venturis, thereby allowing the same carb to be used with many different engines and applications. IDFs (unlike IDAs) do have provisions for cold weather chokes, but most carbs do not have the mechanical parts included, just a block-off plate. Some cars equipped with IDFs as original equipment do have working choke mechanisms installed. In my own experience, I have never needed the choke mechanisms to start my motor, even in temps down in the 20s.

Mike

[347]

Thanks Mike

[Cal Metal]

Virtually no bottom end. I have seen 48 IDAs with no chokes, but you have to be running at the top end of the rpm curve for it to make any sense. Many of the Comp. Cobras like Dan Gerber's, run 45 chokes with 48 IDAs. The jetting is around 175 with air correction jets at 180. This isn't a radical configuration by any stretch of the imagination. There is just very little signal at the bottom end.

Remember, VW performance engines run 58mm IDA's and they don't begin to have the displacement of a SB or BB Ford, on a per cylinder basis. So, your question is a good one, but it will achieve nothing useful for the street.

[347]

Will I benefit going upto 48ida's?
Will I notice much hp/torque increase?

[Cobranut]

Mike,

Thanks for the clarification.
It's obvious I'm not very familiar with Webers.

If the choke is actually the venturi, then wouldn't you have just a straight tube with it removed?
I'm surprised you'd get any signal at all.

Do they have what Holley refers to as a booster venturi? If so, I guess that would provide for main circuit fuel flow.

Later,