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Thread: DHLA Carbs on a Pinto

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    DHLA Carbs on a Pinto - jetting

    I've aquired a pair of DHLA 40's which I have slung on the side of my engine. I know that many people will say I should have put 45s on, but these were really cheap and my engine is fairly standard except for a head skim and cam.

    It seems to start and drive fairly well already, but I can't imagine I have been that lucky!

    Reading up online with regards to the jetting gives some seemingly varied suggestions so I was wondering if someone might be able to suggest what changes, if any, I should make to the existing jetting. There seems to be loads of info for Weber, but just the same piece re-posted everywhere for Dellorto.

    Here is what I have at the moment:

    - 2 litre pinto, Newman PH3 camshaft and 1.5mm (I think) head skim. Standard mechanical pump, No regulator ( I know from my previous post that ideally I need one, but I wanted to hear them first :-) )


    - The carb bodies just say DHLA40, no suffix letter. They are currently fitted with the following:

    36mm chokes
    140 Main jet
    160 Air correctors
    7772.5 Emulsion tubes
    52 Idle jets
    7850.1 Idle jet holders
    33 Accelerator pump jets
    7848.1 Auxiliary vents

    I know a rolling road tune is the ideal answer, but I'd like to get them close-ish and see if I want to keep them before spending too much.


    Thank you in advance

    Richard
    Last edited by emu; 24-11-2013 at 19:48. Reason: title change

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    Re: DHLA Carbs on a Pinto

    im very very rusty regarding jetting, but those chokes are very big and considering that the mains look a bit on the small side

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    Re: DHLA Carbs on a Pinto

    Reading around it does seem that 34mm chokes would be preferable.

    The carbs came with a stack of jets and tubes, but there arent any full sets of anything except emulsion tubes, 165 mains and a set of 32 chokes. I did wonder about trying those, but thought the chokes might be a bit small and the 165s too big?
    Last edited by emu; 24-11-2013 at 20:20.

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    Re: DHLA Carbs on a Pinto

    The e tube number isn't correct above....it should start with an F, F16 is the most common, with 36mm chokes I'd be looking at roughly a 150main......idle jet say a 45f9, there really is no substitute for a dyno session or tune it on the road with a wideband air/fuel ratio meter.

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    Re: DHLA Carbs on a Pinto

    Quote Originally Posted by Erikmex View Post
    The e tube number isn't correct above....it should start with an F, F16 is the most common, with 36mm chokes I'd be looking at roughly a 150main......idle jet say a 45f9, there really is no substitute for a dyno session or tune it on the road with a wideband air/fuel ratio meter.
    you are quoting weber jets! the numbers quoted in the origonal post are dellorto and correct

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    Re: DHLA Carbs on a Pinto

    I've found a copy of "How to build and tune weber and dellorto carburettors" online now, so I will have a read through that and see if I can make head or tail of what it says.

    Any further advice and suggestions are still appreciated though.

    I assume the main jet needs to be bigger with 36mm chokes because they create less vacuum to pull the fuel out with?

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    Re: DHLA Carbs on a Pinto

    I assume the main jet needs to be bigger with 36mm chokes because they create less vacuum to pull the fuel out with?
    yes

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    Re: DHLA Carbs on a Pinto

    Quote Originally Posted by Graham View Post
    im very very rusty regarding jetting, but those chokes are very big and considering that the mains look a bit on the small side
    Check with a jet-gauge or a small drill bit that the jets haven't been bored out.

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    Re: DHLA Carbs on a Pinto

    Quote Originally Posted by Miniliteman View Post
    Check with a jet-gauge or a small drill bit that the jets haven't been bored out.
    Do Dellorto jet sizes work the same way as Weber? So 140 would be 1.4 mm? Does that sizing system apply to the air correctors as well as the fuel jets?

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    Re: DHLA Carbs on a Pinto

    Quote Originally Posted by emu View Post
    Do Dellorto jet sizes work the same way as Weber? So 140 would be 1.4 mm? Does that sizing system apply to the air correctors as well as the fuel jets?
    Yes, this applies to main jets, air jets and idle jets.
    The coding of the emulsion tubes etc is different to Webers.

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    Re: DHLA Carbs on a Pinto

    Hello,
    I have pinto running higher compression, 45.5 mm bvh, rl31 cam etc,
    I am thinking of taking to ht racing to set up dellorto 45s,
    Has anyone got any idea what jet sizes I should be looking at?
    37 chokes
    I have 65 idles.
    200 air correctors, F16s and 160 mains at present.

    i played with standard injection pinto and it did end up having 190 air correctors and 150 mains.
    Can anyone have guess what size I had better buy to take to ht racing?
    Thanks John.

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    Re: DHLA Carbs on a Pinto

    seems a little big. from memory i had
    38 chokes
    57 idles
    150 mains
    190 airs
    45.5mm inlets running a bf63 cam.

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    Re: DHLA Carbs on a Pinto

    I think I may end up with 195 air corrector said and 155 or 158 mains?
    We'll have to see on rolling road.
    Thanks

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