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  1. #1
    Join Date
    Oct 2015
    Location
    Southampton
    Posts
    18

    Edlebrock Carb Tuning

    I have a Dax Cobra fitted with Chevy 383ci V8 stroker engine, 6.3 litre. It is running with a Edlebrock 750 cfm carburettor, Edlebrock E-Tec 200 Vortec alloy heads and Edlebrock RPM Vortec allow intake manifold. It has been running rich and I did drop the jet sizes down by two sizes but still appears to be running rich as smelly exhaust and blackened plugs (see photos)
    Does anyone know a good engine / carb tuner in the Southampton, Hampshire area? Would be good if they had a rolling road as well to set up well.
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  2. #2
    Join Date
    Nov 2008
    Location
    S/W Cornwall
    Posts
    410
    Rob a wealth of excellent information from Pete (sidecarbod on here) can be found here http://how-to-build-a-pilgrim-sumo.w...fueling-system
    After reading this you will probably be able to sort it yourself.
    Cheers,
    Simon

  3. #3
    Join Date
    Sep 2010
    Location
    Cambridge
    Age
    33
    Posts
    1,111
    Hi Rob my 383 originally had an eddy performer 750 and I knew absolutely nothing about carbs to begin with. If you've already swapped jets then you're obviously not averse to having a go tweaking the carb. Do you know if the carb was stock calibration to begin with? I think its 0.113 jets stock. Have you adjusted the idle mixture at all? I've had eddy and holley carbs and its amazing what difference 1/4 turn on the idle mix screws can have. If you know the idle speed/mixture setting procedure then I'd give that a go. If you don't know it then we can help, and the edelbrock manual explains pretty well how to do it. Do you have a vacuum gauge?

    Do you know if the timing is set correctly? I fannied around for ages making changes to my carb and my problem was in fact the timing wasn't optimal.

    As far as rods and jets go I've got full notes at home (working away at the mo) but from memory I ended up with 0.113 jets and 068 x 047 rods and I was getting about 17mpg which wasn't too bad, plugs were clean. Sorry if its insulting your knowledge but are you familiar with the calibration chart? The Edelbrock manual (available in PDF from Edelbrock site) http://www.edelbrock.com/automotive/...ers-manual.pdf is very good and lists jet and rod sizes for a ton of calibration points that make it easy to make an educated guess of what tune you want to go for. My engine seemed to like calibration point 10 which is slightly leaner on cruise but slightly richer on power.




    Do you have a box of different rod sizes to swap out? They have a lean/rich step in them which is activated by vacuum/throttle demand so you may be ok on power mixture but really rich on cruise mixture. Changing the jet will affect mixture across the board but if you want to fine tune one aspect of driving (i.e. cruise) then you're going to have to swap the rods, but its laughably easy

    regards

    Dave
    Last edited by hifihedgehog; 13-09-17 at 02:38 PM.

  4. #4
    Join Date
    Oct 2015
    Location
    Southampton
    Posts
    18
    Thanks will have a read

  5. #5
    Join Date
    Oct 2015
    Location
    Southampton
    Posts
    18
    That is great will have a look. I didn't adjust the carb myslef as did not have the confidence, a chap I know did and will now go back to him and see if he can assist me with your suggestions. Really helpful and much appreciated

  6. #6
    Join Date
    Nov 2013
    Location
    My Garage
    Posts
    721
    Adjusting an Eddy carb is incredibly simple if you RTFM and get the rods springs and jets kit.
    MKIII Pilgrim Sumo. 4 Litre Rover V8

    I DONT NEED GOOGLE. MY WIFE KNOWS EVERYTHING

  7. #7
    Join Date
    Sep 2010
    Location
    Cambridge
    Age
    33
    Posts
    1,111
    Quote Originally Posted by Ken View Post
    Adjusting an Eddy carb is incredibly simple if you RTFM and get the rods springs and jets kit.
    spot on, its super easy peasy. Rods can be changed in less than a minute.

    Take the air filter off, undo the torx fixing on little funny shaped cover, swing it out the way (or remove entirely) and the rod/spring will pop up. Fish it out, stick a different rod on and then pop the cover piece back on.



    Rob - if you've got a few spare mins to have a tinker, first thing I'd do, you don't need anyone to help and its completely reversible, start the car and get it warmed up, then wind in the two idle screws on the front of the carb just half a turn. Wind in = less idle fuel. Wind out = more idle fuel. If the engine picks up and gains speed, runs better, then it was probably a bit rich. If the engine stutters and dies then it was probably set somewhere near optimal so just wind them back to their original position. Simply speaking, the rough aim is to twiddle them around (same each side) until the engine is at its happiest, judged by ear, by rpm (highest value) or by vacuum if you have a vac gauge. You can't miss the screws - two big knurled brass screws on the lower front bit of the carb with springs underneath the head.

    Just start off with easy things like that and build some confidence, DIY rod and jet changes will then seem much less daunting

    Forgot to ask, how old is the engine and does it burn any oil?

    edit: apologies for absolutely massive picture, not sure whats going on there


    regards

    Dave
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    Last edited by hifihedgehog; 14-09-17 at 09:31 AM.

  8. #8
    Join Date
    Nov 2013
    Location
    My Garage
    Posts
    721
    Quote Originally Posted by hifihedgehog View Post
    edit: apologies for absolutely massive picture, not sure whats going on there


    regards

    Dave

    If youre gonna have one...........have A BIG UN
    MKIII Pilgrim Sumo. 4 Litre Rover V8

    I DONT NEED GOOGLE. MY WIFE KNOWS EVERYTHING

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