Currently have weber 48s. runs fine. Possibly want to change to 40s or 44s on 2110. Any advice which would be better suited? Thanks
Bob
Original Post
Replies sorted oldest to newest
Currently have weber 48s. runs fine. Possibly want to change to 40s or 44s on 2110. Any advice which would be better suited? Thanks
Bob
Bob
I have 44s on a 1915, so I think you'd want to stay that large. Otherwise you'll be choking your engine a bit.
I think you'll find that 44's will work better in the low to mid range where you do the majority of your driving. 48's are huge carburetors and work best at the top end of the engine's spectrum however, if the right person sets them up, they will work fairly decent.
Lane, actually you're over carbureted a bit but just as above, if they're set correctly, they will even work on a 1600 cc engine.
Are they 48 IDA carbs? If so they're tough to use on the street but are highly sought after by racers. Worth putting in ebay to let people fight over them.
More likely they're 48 IDF's, no?
A lot depends on how you drive but in general I think smaller is better unless you really must have the redline breathing and spend a lot of your time at high RPM. For a 2110 44 IDF's are a good choice though if you like to keep it below 5500 rpm you could probably run 40 IDF and get good low speed response. I'd go the 44 IDF.
Also, I agree with Jim above me. Too many people when suffering some drivability problem or another blame the carb when the real problem is somewhere else.
More likely they're 48 IDF's, no?
A lot depends on how you drive but in general I think smaller is better unless you really must have the redline breathing and spend a lot of your time at high RPM. For a 2110 44 IDF's are a good choice though if you like to keep it below 5500 rpm you could probably run 40 IDF and get good low speed response. I'd go the 44 IDF.
Also, I agree with Jim above me. Too many people when suffering some drivability problem or another blame the carb when the real problem is somewhere else.
I know of people running Weber 48's on 1720 cc's and they are running extremely well. If you are not happy with the 48's on what you have you need someone who really knows Webers, not smaller carbs necessarily. Proper jets, proper tune, proper emulsion tubes, proper linkage adjustments, right idle jets, proper transition to main jets from idle jets, proper timing, good flow exhaust, Weber 48's can work very well. But, they are not tolerant of a bunch of things being wrong. And if those things are wrong now, changing to 40's of 44's does not automatically improve how your car runs. The same things have to be considered and properly fit on those also. Beware of those who claim going to a different carb will solve any problem...it might, but may generate 3 new problems...and solve none...I had 40's on a 2110 and it definately ran out of breathing room at just a bit over 4500-5000 rpm, and repeated efforts with tuning and other breathng improvements never really solved that problem. The difference between 44's and 48's is not worth the hassle and cost of changing them, and unless you really stay under 5000 rpm I think 40's are too small IMO/IME. YMMV.
Thanks for your thoughts. Only problems are mpg. With the 48s I'm getting less than 17 around town. Yes they're idfs. Don't push above 4500 to 4800 rpms.
Bob- Do you know what size venturis are in your carbs? What cam/rockers? valve sizes and how much porting? exhaust? The rpm peak (or redline) of the motor? Have you tuned the carbs with an LM1 or similar analyzer? A motor running a little rich can get the mileage you're describing, and unless you're really experienced it sometimes takes a lot of trial and error (and a ton of money invested in jets) to get a set of carbs dialed in. A wideband analyzer can be an invaluable tool. My apologies for all the questions, but it's more involved than just "a motor this big runs this size carbs".
The running characteristics of Webers (and Dellortos) can be changed quite a bit by using smaller or bigger venturis. There are limitations, though; ideal is 75-83% venturi to throttle bore ratio and using much smaller than ideal vents can create rich transition and midrange that is hard (if not impossible) to tune out , and vents that are too large for the carbs are often problematic (poor vacuum signal) in all but full throttle situations.
That said, 40mm Dels (34mm vents?) have made almost 160hp in a 2276 with 40x35 heads at 6000rpm (Gerico's build http://www.thesamba.com/vw/forum/viewtopic.php?t=265227&postdays=0&postorder=asc&start=0 I know, I've posted this before). These same carbs would also work well on an almost stock 1600 with a venturi (28mm) and jet change.
The running characteristics of Webers (and Dellortos) can be changed quite a bit by using smaller or bigger venturis. There are limitations, though; ideal is 75-83% venturi to throttle bore ratio and using much smaller than ideal vents can create rich transition and midrange that is hard (if not impossible) to tune out , and vents that are too large for the carbs are often problematic (poor vacuum signal) in all but full throttle situations.
That said, 40mm Dels (34mm vents?) have made almost 160hp in a 2276 with 40x35 heads at 6000rpm (Gerico's build http://www.thesamba.com/vw/forum/viewtopic.php?t=265227&postdays=0&postorder=asc&start=0 I know, I've posted this before). These same carbs would also work well on an almost stock 1600 with a venturi (28mm) and jet change.
Allen, Good questions. All the jets were recommended by pat at cb performance. Runs very well now but mpg way too low.Changing Venturis may be the solution to better gas mileage. Will explore before changing carbuerators.
Bob
Bob
Hi Bob,
About gas mileage, you might want to ask Bruce's opinion about the ignition timing. Mine is a 44 IDF on a 2332, when I got the car new it only went 14 mpg in town. I later found out that it is due to mainly due to the ignition timing not advancing enough (or correctly). Now I am using CB Performance digital distributor and I get 20 mpg in town/highway combo and on the trip to Pismo I got about 25 mpg. going mainly 60-70 mph.
Just a thought.
Eddy
About gas mileage, you might want to ask Bruce's opinion about the ignition timing. Mine is a 44 IDF on a 2332, when I got the car new it only went 14 mpg in town. I later found out that it is due to mainly due to the ignition timing not advancing enough (or correctly). Now I am using CB Performance digital distributor and I get 20 mpg in town/highway combo and on the trip to Pismo I got about 25 mpg. going mainly 60-70 mph.
Just a thought.
Eddy
The jets Pat recommended are a good starting point; a little rich, but your motor's guaranteed to run and not be "lean" (which is sure death). Every motor is a little different (even identically built ones) and it's impossible to recommend the exact jet sizes even when knowing all the specs. Aircooled.net has very good articles on synchronyzing carbs http://www.aircooled.net/synchronize-dual-vw-carburetors-103/ and jetting http://www.aircooled.net/vw-carburetors-jetting-102/ Make sure the valves are adjusted, and as Eddy mentioned, the distributor is set and working properly. It may seem a daunting task ( it will take longer than an afternoon), but when you get it right you will know a lot more about your carburetors and motor. And you'll be surprised at the extra power too! (where's that damn smiling devil emoticon???)
Thanks for the thoughts, guys. Will check it out.
Bob
Bob
I forgot to mention to change only one set of jets at a time and then note the effect. As this may take a few days to get it spot on (if you persevere you'll be amazed at the mileage improvement and extra power! smiling devil emoticon where are you!!), it may also help to keep a log of the changes. Reviewing what you've done sometimes helps understand what's going on.
As I said before, you may think this is above your skill level (I'm not trying to offend, I don't know what you know), but if you can use a screwdriver and wrench and can listen, you can do this. The trick is to pay attention, and always account for all pieces; nothing dropped down the carb throats will just "blow out" the exhaust with out damaging anything. Maybe put rags in the carbs every time you work on it? And count the rag pieces (and everything else) before starting it every time.
Hope this helps. Al
Again, what's in the motor?
As I said before, you may think this is above your skill level (I'm not trying to offend, I don't know what you know), but if you can use a screwdriver and wrench and can listen, you can do this. The trick is to pay attention, and always account for all pieces; nothing dropped down the carb throats will just "blow out" the exhaust with out damaging anything. Maybe put rags in the carbs every time you work on it? And count the rag pieces (and everything else) before starting it every time.
Hope this helps. Al
Again, what's in the motor?
Btw, John Connolly (sp?) at Aircooled.net used to have a jet trading program so it didn't cost a fortune and you didn't end up with a whole pile of jets you'll never use again. Call him.
Bob -
The fact that your 48s are too big for a street driven 2110 is a given. But, as you already have figured out, you can "get by" with what you have and enjoy driving the car.
Your complaint is fuel mileage in 'round-town driving. In round-town driving you are on the idle jets practically 99% of the time. Your 2110 can only suck a fixed amount of air through the carbs. How much fuel comes along with the air is a function of mixture adjustment screw and idle jet size.
Chances are changing idle jet sizes a step or two one way or another isn't going to make anything like a 5 mpg difference. Your engine is still only going to suck a fixed amount of air to operate the idle circuits. The idle circuits are supplying a fuel "mist".
My guess is you are not sucking too much fuel mist, you are pumping too much raw fuel. Your issue might be the accelerator pump adjustment / jet size. Every single time you press on the accelerator pedal (lots of times in 'round-town driving)your accelerator pump squirts raw fuel down the carb throats -- four big squirts per pedal press. Big carbs can be expected to come with big accelerator jets and big pump capacity to provide really big squirts for the really big engines they are intended for.
Check your accelerator pump jet size and your accelerator pump adjustment.
The fact that your 48s are too big for a street driven 2110 is a given. But, as you already have figured out, you can "get by" with what you have and enjoy driving the car.
Your complaint is fuel mileage in 'round-town driving. In round-town driving you are on the idle jets practically 99% of the time. Your 2110 can only suck a fixed amount of air through the carbs. How much fuel comes along with the air is a function of mixture adjustment screw and idle jet size.
Chances are changing idle jet sizes a step or two one way or another isn't going to make anything like a 5 mpg difference. Your engine is still only going to suck a fixed amount of air to operate the idle circuits. The idle circuits are supplying a fuel "mist".
My guess is you are not sucking too much fuel mist, you are pumping too much raw fuel. Your issue might be the accelerator pump adjustment / jet size. Every single time you press on the accelerator pedal (lots of times in 'round-town driving)your accelerator pump squirts raw fuel down the carb throats -- four big squirts per pedal press. Big carbs can be expected to come with big accelerator jets and big pump capacity to provide really big squirts for the really big engines they are intended for.
Check your accelerator pump jet size and your accelerator pump adjustment.