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Thread: DHLA calc check please

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    Spanner Monkey ugg10's Avatar

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    DHLA calc check please

    DHLA calc check please

    I am looking at putting Dellorto DHLA 40s on my engine having manage to get three (which I can make 2 good ones from) at a reasonable price.

    Can someone do a quick check to see if my calculation are correct and if any of the alternatives (from the bits I have) would be OK. Or if someone has fitted them to the same engine and has settings then please can you let me know. Just need to get it running OK for the mot (Historic blue smoke) and then run in ready for a rolling road setup.

    All comments/help will be gratefully received.

    Using Dave Andrews guide - http://www.s262612653.websitehome.co...s/dellorto.htm

    Engine - Puma Zetec SE, 1.7l (425cc/cyl), 16v, Max power at 6300rpm

    Ideal Settings

    Choke size - 34mm from diagram
    Main jets - choke x 4 = 136
    Air corrector - Main + 50 = 186
    Emulsion tubes - 7772.6 (425cc/cyl)
    Idle jet - 45 (1700cc)
    Idle retainer - 7850.2 (suggested for a rich idle then work down from there)
    For pump jets I managed to find this - http://oto.to/schematy/gazniki.pdf (Des Hammill book) which suggests 40 for 425cc/cyl (page 76) and also has the quote about 7848.1 being the most common Auxiliary Venturi.

    What I have

    From my bag of bits I have the following that are close to the above "ideal" numbers -

    Chokes - 4 x 33mm
    Main jets - 2x140
    Air cirrectors - 2x190
    Emulsion tubes - 4x7772.5
    Idle jet - 3x50
    Idle retainer - 3x7850.2
    Auxiliary venturi - 4x7848.1
    Pump Jets - 4x45

    Questions

    So, out of that, as a starter for ten, trying to keep costs sensible (will need a refurb/gasket kit and a couple of trumpets as well !),

    1) Will 33mm chokes be OK
    2) Will 140/190 mains be Ok (they are cheap so happy to change these)
    3) Will the emulsion tubes for the larger engine be Ok (£9 each, ouch)
    4) idle jet size? (again cheap so ok to replace)
    5) pump jets look ok ish.

    Sorry for the long message but hopefully this has given you enough info to help.

    Note, looking to use canems ignition only ecu and control the vct with off up to 2.3k, on up to 5.8k and the off again plus off below 25% load, these setting seemed to work well on another similar engine.

    Thanks in advance.
    1968 Ford Anglia 1.7 Puma engine/Escort front/5 Link rear/RX8 box
    http://www.Anglia1968.weebly.com

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    Re: DHLA calc check please

    Make sure you use 2 carbs which are exactly the same.

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    Spanner Monkey ugg10's Avatar

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    Re: DHLA calc check please

    Thanks, Yep, agree, looks like the three I have are all old pre-emissions ones, only have dhla40 (no suffix) cast into them and have the same progression holes. Two also have the same metal tags with the same number on them so seem to be a matching pair. I will pick the best two, strip, clean and re-assemble with new gaskets and bolts/screws. Got a nice single cable, over the top of the engine throttle mechanism too.
    1968 Ford Anglia 1.7 Puma engine/Escort front/5 Link rear/RX8 box
    http://www.Anglia1968.weebly.com

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    Re: DHLA calc check please

    33 chokes will be ok

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