Dellorto Racing carbs

Hello Anyone , new to this mularky ( forums ) ! Fed up with crap spanish Amals on my Seeley norton has anyone ever used a Dellorto racing carb ? Specifically a R9787 VHSC 39.5 BD carb . They look the dogs and are priced to match but has anyone experience of using them , are they any good ?

Hi welcome on board, hope some gurus could help you , with your Seeley..

Thanks , sure hope so..........!

Welcome Dan, I don't have any experience with the Dell's, but JS Motorsports has a very reasonably priced flat slide set up. Cj

Hi Dan, as you said Seeley, I imagine you had Amal MK2, what size were they (though there is no link between size and problem!)...?, were they flooding?
My own Seeley is still on the bench and will be a gentle one ,though with Jim Schmidt 's pistons/rods and cam (stage one), Maney 750 barrel, but a fairly Std 32mm head (just lightened rockers and black diamonds valves), I had to have machined to fit the 850 pattern 750 head , following Ken Canaga drawings he had post on this forum; I will stick on "small" carbies , and probably Jim Schmidt's flat side , though , I had a pair of Sudco manifolds and a set of 34 VM Mikunis, which I could try at a time......I don't know which Carbs , the guys like 'Homeslice", or Ken Canaga are using , over the pond ??
I was tempted for a while by the Keihin FCR , but they could be "overkill" and pricey!
Only few people here in France are using dellorto on their Norton, or they are the 34mm from old Dukes or Guzzi, never heard about the VHSC .........will ask around ?

Thanks cj, my problem is the 38mm Smoothbores are continually flooding , despite strip-downs and finding small faults such as the brass ring the float needle sits in having a burr on the flow slot ,thus stopping the triangular needle to not sit properly and consequently not stop fuel from flooding in . But the still do it ! My mate has had the same problem , to the extent , minutes after a race it flooded and caused the bike to burst into flames ! Quick alert marshalls saved the situation from being much worse. The bike is a 750 norton , highly tuned , but i am somewhat constrained by CRMC eligibility rules , i can't just put any old carbs on , Gardner flatslides i can as they were avaiable and used in the period , G50 Manx etc , Amals and the Dellorto's . Maybe Gardners are the way to go . Anyone experience of fettling them for a norton twin ?

Late Webers are Spanish too . . .

John Gurney ran Gardners on his Street P R ish Commando , said something about fuel head , and running tank low
giving weak head afeccting mixture . ? So a few gallons in tank neccesary .

Ducatis recently ( why well , in the last decade or two ) Ran IDA & IDF Webers, std on Lancias , Aston V-8 etc .
Seen a few Daytona's ( The 500 TWIN ) late 70s with 40 DCOE Weber fitted. Alledged to work very well .

Pressume on a Commando a 45 DCOE ( 45 DHLA Dellorotto is V similar ) would work rather well.
Chokes are to suit, 45 is the bore size BEFORE hokes fitted, Chokes being Venturies.

Came in 50 & 58 mm too , used on XU1 Toranas utiliseing just one bore , Vanwalls etc .

Should be dime a dozen if just one reqd. If the eligibility types whine , stand on one foot ( theres )
and swing elbows outward .Cant see theyd have a leg to stand on , snivleing pillocks .

Matt Spencer said:

Late Webers are Spanish too . . .

John Gurney ran Gardners on his Street P R ish Commando , said something about fuel head , and running tank low
giving weak head afeccting mixture . ? So a few gallons in tank neccesary .

Ducatis recently ( why well , in the last decade or two ) Ran IDA & IDF Webers, std on Lancias , Aston V-8 etc .
Seen a few Daytona's ( The 500 TWIN ) late 70s with 40 DCOE Weber fitted. Alledged to work very well .

Pressume on a Commando a 45 DCOE ( 45 DHLA Dellorotto is V similar ) would work rather well.
Chokes are to suit, 45 is the bore size BEFORE hokes fitted, Chokes being Venturies.

Came in 50 & 58 mm too , used on XU1 Toranas utiliseing just one bore , Vanwalls etc .

Should be dime a dozen if just one reqd. If the eligibility types whine , stand on one foot ( theres )
and swing elbows outward .Cant see theyd have a leg to stand on , snivleing pillocks .

Click to expand...

Webbers : Guessing these would require a special inlet manifold, Old coopers i had used a manifold with a longish tract,combined with the carb and trumpets {Long] i doubt these combinations will fit into the space? and tricky to set up..requiring lots of expertise and Jets!
Must admit the induction "wail" sounded great, well as the inlet trumpets where inside the car [Dash was cut out ,and speedo removed] i could see straight down the throats :!: When changing gear a plume of vapour would shoot out,inside the car...but as i said the induction throaty roar was fantastic..ear plugs when racing :!:

If the motors run in , Jet from the top ( main jets) F 30 or F 13 emulsification tubes usually do the trick.
Float level bias perhaps , and its money for old rope , if all the rest of the systems are in top order .

Chap who wrote a book on tuning Webers said near all problems were from clapped out engines or grossly inapropriate
fitment .Admitadly , tossing the stock air cleaner , and maybe the rest of the underseat stuff would give you more leeway.

68 / 74 Triumph 500's are ity bity little bikes , the 40 fits in there in front of the seat post no trouble .
Niether of those I saw had any worries with them . Bar throttle cable needs to be set at end of travel W.F.O.
so no strain on cable or spindle .Actually gives light precise throttle opperation , and Webers tend to give overun
modulation , as in you have good engine brakeing control manipulation .

In comparison to the average used Mk 1 Concentric , theyd be a dream to live with .

The tuned induction length is to enhance power at a specific r.p.m. s , worthwhile perhaps raceing ,
but somewhat unnesessary for road use .

G'day Dan, Welcome to the forum.
I understand your frustration, I am currently allowing my Amals one last chance.
hehehe.

Thanks chaps , good food for thought there , the smoothies are currently set up with a tuned inlet tract , so from head to end of trumpet is a good 9 inches ....not actually measured the whole length it has just occured to me ...must do that . :shock: Am gonna get the beast on the dyno in the next couple of weeks , see what the Anals do and beg steal or borrow some Gardners or whatever else i can get hold of , and compare. I suspect tha Anals may well be on the barbie soon ! :lol: