21 replies to this topic

[Gaz66]

I have just watched a video by Mr Vizard where he states Webers are preferred over Dellortos on a Mini due to the fuel droplet size which is larger with the Webers. This I gather is due to the design of the head and inlet ports.
Anyone know if this changes when a 7/8 port head is fitted?
I plan on going down the 8 port route with "the project" if all goes to plan and as sods law dictates I bought a pair of Dellortos last night before I saw the video.

[DeadSquare]

If you lived much closer, I'd lend you a pair of Webbers, so that you cold experience the difference.

 

Two thoughts.

 

With 7 or 8 ports rather than 5, there will be 1/2 the gas flow through the barrels of the carb.

 

An additional advantage of a supercharger, is that the churning of the vanes reduces the droplet size to a gassiest mist.  The smaller the droplet size, the more homogeneous the charge, which produces a more even burn.

[Gaz66]

So if theres 1/2 the gas flow through the inlet ports will it change the fuel droplet size? Im presuming it will, to bigger droplets?
I would have thought that the more atomized the fuel the better it would be but not according to Mr Vizard.
But like I said his findings were on 5 port engines.

[timmy850]

The reality is these days if you want Dellorto DHLA's you need to track down a good used pair (preferably from the same engine) as there are a few different body types. I'd also budget for a rebuild, plus if they are off an Alfa or similar 2.0L engine you may need to replace all the jets and tuning parts to suit a 1.3L mini engine. They will use the same manifold and air filters as a Weber DCOE, but everything else is specific to the Dellorto. By comparison the DCOE is much easier to find new & used 

 

I think you'll find most tuners will have a huge stock of Weber parts, but the Dellorto parts may have to be specially ordered in. 

 

Vizard's yellow says the slight DCOE power advantage (2-3%) is useful for race engines, but the slight economy benefit for DHLA is useful for road going engines. 

[mini13]

in the first "Keep your mini alive" mag there was a section on 7 port heads by visard, iirc he talked about thinking delortos may be better suited, due to the finer atomization as those heads have quite large runners.

personally I'd just look at injecting instead.

[IronmanG]

in the first "Keep your mini alive" mag there was a section on 7 port heads by visard, iirc he talked about thinking delortos may be better suited, due to the finer atomization as those heads have quite large runners.

personally I'd just look at injecting instead.

I've seen this somewhere. If the droplets are to large they effectively drop out as the flow speed is so much slower in the 7 ports. So the finer the atomisation the better for 7 ports.
8 port I thought were a bit smaller port sizer than the 7s but someone else can confirm that.

[IronmanG]

in the first "Keep your mini alive" mag there was a section on 7 port heads by visard, iirc he talked about thinking delortos may be better suited, due to the finer atomization as those heads have quite large runners.

personally I'd just look at injecting instead.

I've seen this somewhere. If the droplets are to large they effectively drop out as the flow speed is so much slower in the 7 ports. So the finer the atomisation the better for 7 ports.
8 port I thought were a bit smaller port sizer than the 7s but someone else can confirm that.

Ye found it . Page 241 of 3rd edition. Use dellortos on 7 ports for finer fuel atomisation due to large port size to avoid fuel drop out

[Gaz66]

So if thats the case for 7 porters theoretically it should be the same or more important for 8 porters.

[IronmanG]

So if thats the case for 7 porters theoretically it should be the same or more important for 8 porters.

I'm not sure about that. I run a cast 7 port and I know the ports are bigger than a 5 port hence the reduced torque below 3000.
I thought 8 port ports were actually in between the 2 size wise. I'm sure someone with an 8 port will be able to tell you

[Gaz66]

Is there any literature available about 8 porters and carb sizing for various states of tune?

[DeadSquare]

Is there any literature available about 8 porters and carb sizing for various states of tune?

 

 

That sort of information is largely integral with and restricted to, the purchase of the head.

[mini13]

the 8 ports should be less prone as the ports are smaller, it really the 7 ports where they ramp up to Weber flanges in a short distance that this applys too... especially the AKM heads that had 45mm flanges rather than the 40mm of the minisport and alloy heads

Edited by mini13, 22 May 2023 - 07:29 AM.

[Gaz66]

Ive just been reading about progression holes in Webers.
It seems they do dcoe carbs now with up to 5 progression holes.
Which ones would be suitable for an 8 port setup?
Anyone know about these holes as they are new to me.

[timmy850]

The progression holes are just inside the throttle blade. They are non-functional until the throttle blade is cracked open, then fuel from the idle circuit is sucked into the engine to provide an immediate surge of fuel (and bridges the gap between the idle and main circuits)

There’s a good explanation here
https://240260280.co...and Tuning.html

[mini13]

I mentioned it earlier, but I'll bring it up again, IMO injection really is the way to go once you've gone for a 7/8port, its so much easier to deal with on an ongoing basis. plus with 3d mapable ignition you get a much nicer driving engine,

 

you can even get Weber look alike inlets with injectors in these days is you really want that look.

 

https://silodrome.co...hrottle-bodies/