Weber,Hpmx,dellortos
This will be a very controversial Topic but this is written from pure experience I build 40 engines a year. Also, I have built and tuned literally 100s of Dual carbs. After these carbs are properly set up and jetted they work amazing. Every once in a while you will have a plugged idle jet, this can easily be remedied by pulling the jet and blowing it out. In the morning it might have some pops or little nosies, just let it warm up and leave it alone it is totally fine. This is not uncommon , but if you have issues when warmed and running you or a professional may need to investigate. Another issue I see is the float needles wearing out after a couple years, this has been monitored in long haul engines but would not be a surprise in any application.After having my vintage dellortos totally rebuilt I was on a mission to see how long I could go with out any adjustments or maintenance. After 3 year, 36,000 miles. Trips from sea leave to 14,000 feet both street and medium off roading. I finally had to open up the carbs. I started to have a slow hot start, too rich issue. I found the needle had worn a ring from contact with the seat on the 1/2 bank . Not an uncommon or hard problem to fix, this is a wear part.Still studying my engine I only repaired the problem side. About 3 months later I developed a drip from the 3/4 bank and the same problem was evident on the opposite side .
The empi cross bar linkage works fine it is nothing special ,it does get the job done when set up correctly, this is the standard on our basic kit builds. The CB linkage is a slight improvement and little more rigid.
The gene berg linkage is the best of the best, super strong and over built, smooth and robust Adjusting the down bars is a little cave man but lasts forever and never needs reset after the initial in my test. This is what I run on my personal engines, 10s of thousands on trouble free miles. This is an additional upgrade but well worth it.
Down to the nitty gritty, In my opinion the Empi Hpmx carb kits are the best NEW 40 and 44mm carbs on the market. I know that sounds crazy yet time and time again their quality impresses me. After a preset and run through these carbs work flawlessly. Very tunable and long lasting. These are our go to carbs for our 40 and 44mm engines.
I do not prefer the Spanish webers that are on the market today. In 2023 we bought 6 brand new sets from our supplier and every set had defects.I fear that weber is trying to keep a competitive price point and there quality is suffering because of it.
Dellorto carbs are very tuneable and great carbs. Intact I was raised tuning these carbs from a little kid on our euro dirt bikes and motorcycles. Simalar to the Webers in a lot of ways but what I would call very “finite adjustability”. It makes set ups a little more time consuming, I think they run more on the idle jets and the mixture screws are much longer and takes more ‘turns’ to dial them in.These carbs have not been produced since the late 90s so parts can be scarce. We will run your old dells if they are in good shape, if they have a lot of issues we recommend sending them to Rick Hunt for rebuilds as he has built many sets for our shop and is the go to dell guy.
Picking the right carbs and ventures is something that I find so important. Most people always think the bigger the better. This to me is totally wrong ,larger carb bores allow for more air and fuel flow but this scrafices port velocity. I normally do not like larger carbs and vents. The ventrue size really should be matched to the desired engine rpms.The smaller vents lower your peak power, and sets your rpm speed where your engine is most comfortable. Smaller carbs and vents make more torque while larger once make more top end HP. Almost all bus engines should run no bigger than 40mm carbs. Even 2.0 or bigger beetle or race engines work incredibly well with 40mm carbs and upgraded vent 30 -34mm. finally the 36mm vent found in stock 44mm are capable of 8-9-10,000 rpms with a power band in the 45-5000 rpm range. For a street car no one is running there engines this tight. There for if you don’t plan on running your engine at wide open throttle all of the time I think you are leaving so much drivability on the table.