Trying out a set of Weber 44's on our recent build, 96mm x 71mm with Elgin street cam.
The engine barely runs with the 44's, but runs fine with Weber 40 IDF's. Just for fun I stuck a few strips of duct tape over the top of the 44's leaving about a 3/8" slot for air flow. Engine at least runs with the duct tape in place. The 44's have 36 vents and the 40's have 28 vents.

I tried the 44's based on another thread here with the OP claiming how great his 2.0 runs with the 44's (36 vents). Am I missing something? or simply tooo much carb?
Thanks

Way too much carb for street use with a 2.0L engine. Your experiment shows that you're not developing a good vacuum signal at the venturi. Way to many cars out there that are over carbureted. I'd laugh harder but I did it twice when I was younger cause' I was a slow learner.

1st time at ripe old age of 18 on 1973 BMW 520 running dual Strombergs while in Italy. Looked cool. Ran like Scrounged junkyards for the OEM manifold and carb (some basic single barrel Solex that looked pitiful). Ran great both around town and up to top speed of about 110mph on the Autostrada.

2nd time at 20 years old 40 IDF's running 34 venturi's on a stock 1.7L 914.

Learned about how to tune based on that initial 914 failure. Ended up down at 28mm venturi that I bumped up to a 30mm when I rebuilt to 1911cc and a hotter cam. That 30mm sucked for round town driveability below 2500 rpm, but still being young I thought it made better power up top. I was probably kidding myself in hindsight.

2056 should run ok with 44s and 36 primary vents, although it won't make great low end power. If it barely runs you have other problems.
The idle circuit will still distribute fuel with big venturis as long as the jetting is adequate.

IMO 914 engines are not designed to be run on the road at rpm less than 2600.

I generally agree, but i had a really bad habit of accumulating tickets when in my 20's with a red 914 and winding it out in town. Can't tell you how many times I had the following conversation:

"Yeah, . . . . I know the speed limit . . . it only sounded like I was going fast".

Thanks, I was hoping for this engine to at least run decently with 44's, but no. My gut is telling me the 44's with 36mm vents are allowing just too much air volume, hence the duct tape. After switching to a pair of 40's, everything seems fine. Hopefully later this week I can get the PP installed and get her on the road for an Italian tune up.

thats a lot of venturi

for a race car with 7000 redline, I bet they make great power
but your loosing signal at lower rpm... probably anything lower than 3500rpm


my race car is super over carbed... but its a race car. so I changed all of the gears and keep it over 4500 rpm in all of the corners to address the lack of signal at low rpm.


brant

Scroll down about halfway:

http://www.914world.com/bbs2/index.php?showtopic=358140

Thank you everyone for the replies. I tried the 44's due to the fact another member claims to be running them with great success, but I had the 40's in my back pocket just in case.

I know many guys prefer FI of any variety, but being old school I like dialing in a set of carbs anyday in comparison to fooling with especially 50 years old Bosch stuff

32mm Venturi for the 2056. Easy swap.

Currently there are 36 vents, will changing to 32's make that much of a difference? Pegasus does not show 32's, only 34's and 36's. I wondered if 30's are available

Don't quote me but I seem the remember 32mm are the smallest you can fit.

Aircooled.net lists a 32mm venturi for Weber 44 IDF.

http://vwparts.aircooled.net/Weber-44-IDF-...i-32mm-pair.htm

And a 30mm for Weber 44 IDF.

http://vwparts.aircooled.net/Weber-44-IDF-...i-30mm-pair.htm

I think that is true and search of CB performance also shows 32 as smallest for 44IDF. There is always the guy on Ebay Alpha1750 that has odd stuff like larger vents for Zenith's. Might see if he offers a smaller vent for 44IDF custom made.

Please see my post # 13 above. It appears a 30mm may be available.

oops

It looks as though 28mm may be available from Pierce, but they are listed as: .280, .300, .320, .340 and .360. I will call them tomorrow to get the scoop.

Assuming everything being the same, jets, E tubes, venturis, .... will a 44IDF perform the same/similar to a 40IDF?

Not really.

44IDF's have 10% more circumference around the butterfly diameter. This is where the air begins to flow at early transition from idle to mains.

At WOT 44IDF's have 21% more flow area. The increase in area acts to slow down air velocity though the carbs, and in the manifolds. Even if you speed up the airflow at the waist of the venturi with a smaller venturi, the airflow will slow again once it reaches the larger throttle bore of the 44's, more so than it will slow in the 40IDF.


Neither of these numbers seem huge at first glance, but they are significant changes between the 40IDF's and the 44's. if they didn't matter, there would be no point in having two different carb bore / throttle plate sizes. The simple fact is the 44's are the big brother to the 40 IDF's and were intended for larger displacement motors.

There will always be differences in throttle response. Can you tune around them. Yes - with compromises on the low end drive ability.

Depends how much time you spend at WOT. Real world driving? not so much. The chart in the CB manual may indicate 36s but will make for a crappy vac signal at idle and thru the transition circuits. When I handed my 44s over to A.C.E. they were built to perform on a 2056 with a Raby grind cam. Came home with 32s installed and jetted to R.A.T. specs.

Thank you all for the replies, somewhat what I was thinking. I will get this new build running with 40 IDF's and later play around with the 44's (with 32 vents). Other members have stated they are running 44's with a 2056 displacement and mild street cam.

Being an old guy, this will live at WOT very infrequently. My wife often wont' let me drive, because "you drive like an old man" I suppose worse things could be in her vocabulary.

Thanks again, hopefully others can also use this information