ianclark1275
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| posted on 27/2/11 at 05:06 PM |
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Anyone got Dellorto 40's on a 1300 XFlow?
Struggleing with setting up the carbs top get the car running something like, just to give it a bit of a shakedown before we put the bodywork etc.. on
finally.
have read "how to build and power tune webber and dellorto carbs" but wondered if anyone has any other suggestions / ball park
settings/numbers?
it has been running albeit rough. (spitting back thro carbs etc..)
Twin DHLA 40 - N (5 progression holes =emmissions)
rebuild kit fitted.
Main jet = 148
Emulsion tubes = 7772.11
idle jet = 57
Pump jet = 38
Chokes = 27
it had 32 chokes but i changed them for 27.
seems to be set up for a 2.0L but before we set off to boggys, (last time i went and watched him do a dellorto car and he had a box of spare bits
etc..) i want to at least have it somewhere close.
standard 1300 LC with FORMOCO blue GT cam.
.JPG)
My own comment to this would be "leave till the rolling road!!!" but just thought id ask.
measure twice, cut once, scrap it, start again.
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SPYDER
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| posted on 27/2/11 at 05:13 PM |
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I would have thought that 27mm chokes would dictate a smaller main jet than yours.
I would try 125 as a starting point.
Geoff.
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Chippy
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| posted on 27/2/11 at 05:15 PM |
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I think that "Smudge88" has that set up, may be worth dropping him a U2U. HTH Ray
To make a car go faster, just add lightness. Colin Chapman - OR - fit a bigger engine. Chippy
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Dingz
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| posted on 27/2/11 at 06:46 PM |
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148s will be much too big try looking on Dave Andrews site D A there is lots on there
including a rough calculator for jets,
Phoned the local ramblers club today, but the bloke who answered just
went on and on.
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ianclark1275
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| posted on 27/2/11 at 11:46 PM |
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thank you for the replys.
IC
measure twice, cut once, scrap it, start again.
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cliftyhanger
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| posted on 28/2/11 at 07:52 AM |
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just had a look at the des hammill book. He mentions that some dellortos have a fixed air bleed. It is in the middle of the jet "island".
The fixed (2mm) bleed hole is not recessed approx 8mm as the normal type are. This can make them impossible to tune for smaller engines (apparently)
but there are some ideas about fitting a sleeve to reduce the size of the air bleed.
The other indication that this may be the case is that the idle is 57, pretty large unless it is a fixed air bleed.
Hope that is helpful. Better to check and hopefully it isn't an issue.
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Mike Wood
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| posted on 28/2/11 at 11:21 PM |
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Try the long-time Dellorto importers in the UK, Eurocarb for advice, as well as spares: www.dellorto.co.uk
Cheers
Mike
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Mike Wood
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| posted on 28/2/11 at 11:35 PM |
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Sorry for the daft questions, but is your throttle linkage smooth and synchronised?
What kind of linkage have you got? You might want to look at one of the substantial ones available, for example search 'linkage' on
www.dellorto.co.uk (Old school Magard Motorsport linkage were common fit for twin Weber carbs on race and rally cars, see repo version:
http://www.fuelsystem.co.uk/DCOE%20-%20DHLA%20Throttle%20linkage%20kits.pdf)
Also have you got the correct washers inbetween the carbs and manifold - a normal gasket on its own makes for bad running carbs; see:
http://www.merlinmotorsport.co.uk/p1990/CARBURETTOR-SPACER-PLATE-(MISAB)/product_info.html
Apologies if you've done all this.
Mike
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hrc450HRC450
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| posted on 1/3/11 at 11:24 AM |
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I had a set on my capri some time ago.
used a wideband lambda to get it right.
don't know the settings, i'm afraid.
what i do know is i had to glue in a bootlace ferulle in the air supply underneath the lid to get it right.
only in the 5 progresion hole version (DHLA40H?)that was needed.
cheers
carlos
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ianclark1275
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| posted on 22/3/11 at 10:08 PM |
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Mike
Thanks for the reply, yes the gaskets and washers are all the rubber type.
and no, we definately dont have a smooth throttle, its a lash up at the moment but will get something sorted.
Cliftyhanger
thats exactly the nuggets of info that help! i will have a look.
Thanks
IC
measure twice, cut once, scrap it, start again.
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alfas
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| posted on 16/11/12 at 07:06 PM |
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quote:
Originally posted by cliftyhanger
just had a look at the des hammill book. He mentions that some dellortos have a fixed air bleed. It is in the middle of the jet "island".
The fixed (2mm) bleed hole is not recessed approx 8mm as the normal type are. This can make them impossible to tune for smaller engines (apparently)
but there are some ideas about fitting a sleeve to reduce the size of the air bleed.
The other indication that this may be the case is that the idle is 57, pretty large unless it is a fixed air bleed.
Hope that is helpful. Better to check and hopefully it isn't an issue.
yep...and those DHLA 40 "E" carbs are of those low emission carbs which are not suitable for small engines, surplus extremely difficult to
set-up.
i had a similar problem with such carbs...even they had been in perfect nick i changed them to some "old", ones and immedately had a
reasonable idle.
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Paul Turner
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| posted on 19/11/12 at 03:57 PM |
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It will never run correctly (or at all) with the front airfilter covered in tank tape. Cylinders 1 & 2 will not be getting any air.
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alfas
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| posted on 19/11/12 at 09:05 PM |
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have now found some interesting info about those carbs...correctly jetted they might be the best you can get:
Type 3 DHLA40F-G-H-N-R-S models. These are called emission completely different to the DCOE science, but no-one really understands them and tries
always to tune them like the early models. These differ because they have more progression holes and use the idle jet to feed most of the cruise phase
and low rpm/low TP area of the engine AT ALL TIMES when the main jet isn't in operation completely automatically no jetting needed. The idle jet
has a very large fixed 2.2mm air feed, you cannot tune this phase of the carburettor for length like the others, but here lays the secrets....
The idle jet doesn't feed from the float bowl, it feeds directly from the main jet stack, what happens after this is what gives these
Dell'Ortos the sweetest road behaviour (what 25years of research came up with and not just for emissions) and dead easy tuning, you see when the
main jet starts to emulsify fuel in the tube, the idle jet is feeding from it, so the gassy airy fuel shuts down the idle jet and sucks backwards yes
BACKWARDS through the idle!! using every drip of fuel efficiently without ANY waste in circuit cross over where one is going after the other...this
happens the moment the main jet fires, so there is NO need at all to tune the length of the progression and idle phase. This is pure magic they are
automatically calibrated, you simply keep the idle jet above 59 up to 62 and not make the mistake of fitting numbers suited to the early DHLA or DCOE
- with this simple technique you can tune anything from a 1300 to a 2000cc without really doing anything. The emulsion tubes in these carbs are always
8-10-11 and have to stay that way - which are really rich and have a hole straight down with loads of air holes, these atomise the fuel to an massive
degree, also they have to be used cause the idle jet will not run correctly using the DHLA40-E type tubes (1-6-7-5) as the idle jet needs these airy
tubes to function and cut out as designed...Usually people ram the DHLA40 idle holders with air holes in these carbs add the 1-6-5-7 style tubes and
wonder why its a massive lean spot off idle, cause they missed the point completely!...These carbs use a .3 vent which has a very small signal tube to
the main jet stack, this is because the holey tubes are basically ready to go from about 1250rpm (on my car using an 8tube 1 vent it was on the mains
at 1250rpm!) so the holey tubes need holding back with a signal killing venturi...These carbs are wicked if you want bolt on power, they tune
themselves!
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