View Full Version : dellorto dhla 40's
retrosi
06-03-05, 10:38 PM
Just a little bit of help needed....
Are there any problems with these carbs? Anything that i should look out for?
and....
What is the best linkage for these and where can i get them from?
Cheers
the main problem would be if you have a set of the emmision versions(DHLA,H), these were standard fit on some car's (alfa's) and have holes to set the air bleed for the idle control. these are set for bigger engines, so on a smaller engine the idle and low rev's drivability will not be very good. these are what i have and i can live with it quite easily, but that's probably because i'm used to it and have never had a 'proper' set of carbs.
retrosi
06-03-05, 10:56 PM
cheers benji...
Is there any way of changing these holes to suit the engine? I did notice that there is a set of emmisionless carbs on ebay just now.
retrosi
06-03-05, 10:58 PM
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&category=72205&item=7958711192&rd=1
nope, you can't change them.
the carb's on ebay will be idea for what you want, and are a bargin if they go for within ?100 of that price. what engine are they going on? he said he can supple 27, 32 or 35mm chokes. 27's are a bit small for a 1300, 32's would be good for a tuned 1400 or 1600 and 35's ar good for a well tuned 1600 or higher
retrosi
06-03-05, 11:04 PM
1300sr 1989 benji
retrosi
06-03-05, 11:09 PM
so i couldnt use 27mm chokes? would it be better with 32mm??? what linkage should i use?and do you have to fit a manual choke? not 100% sure about this sort of carb!?!?
what other work do you have done? the 27mm's should be ok, maybe a little on the small side, but that would just mean the power band will be a little lower, peak power would be a bit less but midrange will be better.
the sport's came with 28mm chokes
Snowface
06-03-05, 11:49 PM
the emission type carb's have a 2.1mm air bleed hole drilled into the actuak body. If you really wanted to you can get tiny sleeves mad up to slide in and reduce them to say 1.5mm.
I havn't bothered though.
I have a quick question, i get that you have to change the choke size for different sized engines to supply right amount of fuel.
Is changing the choke size also known as re-jetting, or are they two different things?
Snowface
07-03-05, 12:04 AM
different.
the jets are what control the amount of fuel that mixex with the air,
the bigger the jet, the more fuel.
Chokes are these.
http://i18.ebayimg.com/01/i/02/2b/7b/7f_1_b.JPG
they fit inside carb after the venturi.
different.
the jets are what control the amount of fuel that mixex with the air,
the bigger the jet, the more fuel.
Chokes are these.
http://i18.ebayimg.com/01/i/02/2b/7b/7f_1_b.JPG
they fit inside carb after the venturi.
Cheers snowface :D :+:
jet's are basically just screws with a hole drilled in them
What are the chokes for? Do they have a particular function.
retrosi
07-03-05, 05:45 PM
benji....you could post some closeups of your carbs/linkahe/fuel line set up could you? Im intending on putting a fast road cam in as well by the way
benji....you could post some closeups of your carbs/linkahe/fuel line set up could you? Im intending on putting a fast road cam in as well by the way
have a look at my feature, it's the one called ben curry's swing
dunnno if this helps, but these are my 40's off of the engine.
http://img.photobucket.com/albums/v626/j829nick/IMG_0641.jpg
you can see the linkages, fuel set up e.t.c
The only bit that is different to ones actually runing on the car, is where the Spindle is drilled and attached which links each throttle to one another.
i can take some shots from underneath if you like ?
Snowface
08-03-05, 10:59 AM
What are the chokes for? Do they have a particular function.
My interpretation:
Choke act like a barrier almost to the air-fuel mixture. They sit inside the carb's after the venturi.
The ones pictured are 30mm diameter. The smaller the choke, the more resistance almost, (the air/fuel has to squezze through a tighter space) so the smaller chokes create more torque and power lower down the rev's.
Bigger chokes flow more and are for getting power at high rpm's.
Just a basic concept, may not be that accurate.
What are the chokes for? Do they have a particular function.
My interpretation:
Choke act like a barrier almost to the air-fuel mixture. They sit inside the carb's after the venturi.
The ones pictured are 30mm diameter. The smaller the choke, the more resistance almost, (the air/fuel has to squezze through a tighter space) so the smaller chokes create more torque and power lower down the rev's.
Bigger chokes flow more and are for getting power at high rpm's.
Just a basic concept, may not be that accurate.
Cool, thanks mate.
retrosi
08-03-05, 07:30 PM
so are the best ones to get dhla non emmision type?
yes. they are called DHLA no extra letters, and they have black tops. i have one in the garage, it would need new jet's and chokes but you can have it for ?25 if you want.
Snowface
09-03-05, 11:48 AM
they are preety rare aswell.
retrosi
10-03-05, 06:21 PM
right....next question..... is the kent fast road cam the best to run using them? and whats the fuel consumption like...ie how many miles per full tank roughly? cheers guys
Snowface
11-03-05, 12:58 PM
any high duration cam will give you a good increase.
So kent ast2
piper 285/300
i get 32-38mpg on mine. (check my feature for spec).
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