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  1. #1
    Matrix 200 suparoo's Avatar
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    High Speed Screws on CDKII's

    Im going to send off my carbs to Wetwolf to get the high speed screws fitted. After mucking round all summer I think I've finally got the jetting close but will get the screws fitted to fine tune it the last bit. I stopped using the avgas mix and are now using Lucas octane booster. Did heaps of research and all the test gave it the best rating.

    http://volvospeed.com/Reviews/octane_boosters.html

    Point of interest dont use tolulene to boost octane couldn't find one could test result on it. Anyways my question is once the high speed screws are fitted does the jet used set the maximum or minimum fuel flow and about how many jet sizes does the adjustment give?


  2. #2
    Lake Mead Bum & BTLS Mark starflight's Avatar
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    Quote Originally Posted by suparoo View Post
    Im going to send off my carbs to Wetwolf to get the high speed screws fitted. After mucking round all summer I think I've finally got the jetting close but will get the screws fitted to fine tune it the last bit. I stopped using the avgas mix and are now using Lucas octane booster. Did heaps of research and all the test gave it the best rating.

    http://volvospeed.com/Reviews/octane_boosters.html

    Point of interest dont use tolulene to boost octane couldn't find one could test result on it. Anyways my question is once the high speed screws are fitted does the jet used set the maximum or minimum fuel flow and about how many jet sizes does the adjustment give?
    It's my understanding that the adjuster is in addition to the high spd jet. It doesn't adjust what goes through the main jet. I've read that if you need to turn the adjuster more than 2 turns, you need to go up 1 size on the main jet.

  3. #3
    I like Boobs. wetwolf's Avatar
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    Quote Originally Posted by starflight View Post
    It's my understanding that the adjuster is in addition to the high spd jet. It doesn't adjust what goes through the main jet. I've read that if you need to turn the adjuster more than 2 turns, you need to go up 1 size on the main jet.
    Thats about right.

  4. #4
    ph2ocraft's Avatar
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    If I have to turn out 11/2 turns I like to go to the next jet size. I find with the age and tension on the springs at 2 turns you start getting adjustment screws turning out of place due to vibration.

  5. #5
    I like Boobs. wetwolf's Avatar
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    Quote Originally Posted by ph2ocraft View Post
    If I have to turn out 11/2 turns I like to go to the next jet size. I find with the age and tension on the springs at 2 turns you start getting adjustment screws turning out of place due to vibration.

    Good point Al.

  6. #6
    Matrix 200 suparoo's Avatar
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    I had a look at the cut away off the CDKII's on there web site and yes the screws just let more fuel in as a by pass on the main jet.

    The jetting I got too that works best seems to be slightly over 150's (say that cos ive been drilling and filling jets to get it close then using the drills like reamers to finely adjust them) and 153's, 155's so was wondering if 150's with screws will go out to 155 or I need to mix and match jets to get close and fine adjust from there.

    I agree that if you go out more than 1 1/2 turns you need to go up a jet size but how may jets sizes does 1 1/2 turns cover ??
    Attached Files Attached Files

  7. #7
    Rasta Mon Condoms We Be Jammin!!!!! TxVirageTx's Avatar
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    1/8 turn

    i always thought 1/8 turn was a single digit.ie 150 jet plus an 1/8 out= 151,another 1/8= 152,etc..

  8. #8
    Matrix 200 suparoo's Avatar
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    That's good info will certainly keep the price down not having to buy a heap of jets.

  9. #9
    Matrix 200 suparoo's Avatar
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    This was the wash on drilled 150's which really could be anything due to drilling not being an exact science but that would be a good jet size I'm thinking. (New ones of course) Should cover all three pots. I'll post some pics of what it looks like after I drilled them out a little more tonight once I've taken off the head but it looks good through the scope.
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