Sidedrafts: Dellorto vs. Weber?

[rctid]

For those of you w/ sidedraft experience:

Is there an advantage to the Weber 40DCOE over the Dellorto 40DHLA? I've got a rough set of 40DCOE's that will require machine work & a lot of spare parts to make whole, and I've got a line on some fully rebuilt Dellortos. Is it worth it to make the webers work, or should I spring for the Dellortos?

[andyleonard]

Back in the day, when we had a choice and they were the same price, we chose the Dellortos because they has a much wider idle range of adjustment. Assuming prices were equal and all parts were at hand, you'd still have that small advantage. I've never heard of one being better than the other. I have had Dellortos on my car forever and a couple of sets of Webers on the bench. No reason to swap them.

[eurotrash]

Andy, how do you feel about the 'emission' versions? I have a set of "H" designated, sequential serial numbered carbs. At first, I was perturbed at the differences and the the non-lettered carbs being more like the DCOE as far as tunability.. but then I read this.. Its kind of interesting.. Do you have an opinion on this guys logic? It's all an interesting read, but particularly once he gets down to the "Type 3" section.

http://2108.lviv.ua/archives/dellorto-dhla-40-universal-performance-112.html

Here's a screen grab just in the case that the site is an issue..

[andyleonard]

I'm not going to be much help here. I know the smogger Dellortos (G/H/etc.) were common on the 2 liter Alfas and a couple of the Lotuses, were easy to tune, but always felt slightly mushy in terms of throttle response compared to the older ones. Like the man said, they were smooth and easy to set up on a street car but if you started getting stupid with cams and compression (pulse) they would get you lost. Mine have the separate feeds to idle and mains. No idea what letter mark they are. They're old. Sorry. If I had 'em, I'd use 'em. Make sure the accelerator pump diaphragms are fresh before you mount them.

[AustrianVespaGuy]

I really don't think there's a significant difference between the two. Between two specific sets of carbs I think you should just choose whichever you feel is in better shape and/or which model you are more familiar/comfortable with tuning. Maybe it's easier/cheaper to get parts for the Webers but really not sure. As a side note, I really liked the DCOM carbs I ran on a car once; only difference from the DCOEs is the Ms have a diaphram-style acceleration pump and they have smaller, more numerous progression holes, both of which I felt were smoother on light throttle and during throttle transitions.

-Carl

[eurotrash]

..As a side note, I really liked the DCOM carbs I ran on a care once; only difference from the DCOEs is the Ms have a diaphram-style acceleration pump and they have smaller, more numerous progression holes, both of which I felt were smoother on light throttle and during throttle transitions.

-Carl

From what I have read, the DCOM with its accelerator pump, was a short sighted project late in the Italian DCOE era. Fuel injection doomed that specific carb, and then DCOE production went to Spain.. It was a design directly knocking off the late DHLAs, but too little too late.

But they seem to be VERY popular and hard to find.

[PatAllen]

I have a set of vintage 40's DHLA. I messed up a lot on a weber set-up on my friend Lotus when he still had that bda engine. didnt liked them.

Personnaly i think the DHLA are made more stout, they runs on true bearings, and seems easier to tune from what i read altough i didnt ran them yet (the dhla). but i dont like the acc. pump mehcanism on the dhla.

[AlanM]

Having played with both over many years, I really couldn't say one was better than the other, except that in this part of the world, tuning parts are more available for the Webers.

[02for2]

I've likely posted much of this before, but...

There's no difference between the performance potential of Weber DCOE and Dellorto DHLA carbs once setup properly; however, they're not simply clones of each other. There are very distinct differences between them. And there is a huge difference in getting them properly setup.

Webers were initially designed for Racing, where the carb spent most of it's time at WOT. Early italian manufacturers such as Alfa Romeo and FIAT had difficulty adapting them to their street cars. Dellorto came along and used the excellent Weber design, but perfected it for street use. Both of these carbs are now close to 100 years old.

Personally, I prefer Dellortos. But, I'm not trying to be contraversial here - if you like Webers, use them.

One of the reasons for my preference is Dellorto calibrated parts, like jets and mixture screws, offer much finer resolution - you can be more exact in adapting them to a particular engine.

Weber Main Jets are available in size steps of five - 130, 135, 140...etc.

Dellorto's are available in steps of one - 131, 132, 133, 134...etc. Same with Idle Jets, Accelerator Pump Jets, etc...

The Weber Idle Mixture Screws have blunt tapers and coarse threads, while Dellorto's have long slender needles and fine threads. Weber mixture screws usually end up adjusted about 1 1/4 - 2 1/4 turns out, while Dellorto screws end up 2 3/4 - 3 3/4 turns out.

Overall, it's much easier to achieve a very exact mixture setting with Dellortos, while you must take larger steps with Webers that just sort of get you in the neighborhood.

For tuning, the Dellorto is ported to accept a 4-pot manometer such as the Morgan CarbTune II. With this, you can dial in the carbs within 99% in under 10 min., all the while keeping the air filters in place and accounting for them. The Webers rely on an airflow meter, such as the Carb Sync which literally sits between the intake air to the carb and can disupt the very thing you're trying to gauge, plus it doesn't take the airfilter into account.

The Weber progression circuit often has only 2 or 3 holes, while Dellortos have 5 or 6. The Dellorto 6-hole progression is a Lotus development for their own models. Because it worked so much better, Dellorto later adopted this across their full product line.

The 6-hole setup gives the Dellorto a much smoother progression off-idle so the carbs depend less upon a heavy shot from the accelerator pump.

The Weber uses a big pump shot. So much so that Weber carbed engines often deliver significantly shorter piston ring life compared to Dellortos because the big shot from the Weber washes the oil from the cylinder walls.

The Weber accelerator pump's piston runs in a bore machined into the body. It's metal to metal, is subject to "blow-by" due to clearances, tends to wear over time, and the bore cannot be repaired.

The Dellorto diaphragm pump has no blow-by and clearances don't wear with use. Then when it does get old, the pump is easily rebuildable back to 100% spec by simply replacing the diaphragm and gasket.

Webers are much more prone to leak. Dellortos don't. In fact, Lotus switched from webers to dellortos specifically to correct fuel leakage issues.

So, while more difficult to find, and with a more limited number of parts suppliers vs. Webers, I'd still take Dellorto DHLAs over a set of Weber DCOEs any day for the reasons stated. But, having said that, they are both great carbs.

Cheers!

[kbmb02]

I've likely posted much of this before, but...

Now that was a good read. You've motivated me to give the pair of Dell's I've got in a box a good look-over. (For those interested, there's a vendor in Southern California who's got a plethora of Dell'Orto jets, rebuild kits, etc - email me for info). -KB[/i]

[02for2]

I've always had good luck working with Eurocarb Ltd. from the UK - http://www.dellorto.co.uk/.

They also do Weber as well.

Cheers!

[jgerock]

I use the downdraft version in my VW and love them. IMO, it comes down to personal preference. You can get the Dellorto parts from CB Performance in Farmersville, CA.

[LimeySteve]

I concur with 02for2 I run Dellortos on my daily driven track car to say I'm happy is an understatement . Parts from The UK too quick & easy, I run twin 45 DHLA's with a Crane fireball ign , 284 cam (need a bigger cam now) an Ireland stepped street header & my car runs brilliant. With the A/F meter I have a set up of 36 chokes, 130 mains 7772.5 emulsion tubes 180 air correctors 60 idle jets in a 7850.1 holder with 42 pump jets. It should not run & be super lean !!

I am at 14.5 A/F at idle 11-12 at acceleration & high 13's at freeway speeds, no lean pop & I have had that with the old 40's & it runs at 185 degrees on a mech VDO temp gauge . Accelerates clean through all the gears maybe when I put the larger cam in I'll be moving up a size or 2 .Time will tell.

Great carbs mine are DHLA 45C models.

[jdeitch]

I've been running Dellorto DHLA40 carbs on my M10. I just purchased a set of DHLA45 for a upcoming engine project. LimeySteve I may be asking a lot of questions soon

[LimeySteve]

I'll help if I can  , I love my 45 DHLA's