carb recomendations please, have new eddy 750 it just sucks

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    Author Topic: carb recomendations please, have new eddy 750 it just sucks  (Read 2092 times)

    Offline geneo4116

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    • 70 rt 383 auto blk/blk apprx 450hp
    carb recomendations please, have new eddy 750 it just sucks
    « on: July 27, 2008 - 11:09:11 AM »
    motor rebuilt, small high energy cam, ported and polished heads ,bigger valves,eddy rpm intake,tti headers, elec dist, 323 gears .shift kit, 383 ,727, carb is falling on its face off the line, popping at 30 mph kick, sometimes surging at high rpms, beem adjusted and tuned by carb guy, better but still redickulous,cruisng down highway at 60 70 80 just fine, thinking about replacing with quick fuel carb what do you think, also 750 or 850 ???
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    Offline 71chally416

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    Re: carb recomendations please, have new eddy 750 it just sucks
    « Reply #1 on: July 27, 2008 - 11:12:16 AM »
    Get a new carb guy  :thumbsup:
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    sleepychallenger

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    Re: carb recomendations please, have new eddy 750 it just sucks
    « Reply #2 on: July 27, 2008 - 11:24:23 AM »
     :iagree:
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    Offline 71chmark

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    Re: carb recomendations please, have new eddy 750 it just sucks
    « Reply #3 on: July 27, 2008 - 11:31:02 AM »
    Love your car.
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    Offline Harts56

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      • 70 Challenger Convertible
    Re: carb recomendations please, have new eddy 750 it just sucks
    « Reply #4 on: July 27, 2008 - 12:34:22 PM »
    I have nearly the same set up, except with a 440.  I also ran the eddy 750.  If you really love the carb you can get a kit and play with jets and metering rods and it will run OK.  Just takes a little time playing with it - trial and error stuff.  I got mine dialed in pretty well but still was not happy with throttle response so I changed to a QuickFuel SS830 double pumper, mechanical secondaries with a choke!

    Night and day difference!  Great throttle response low end and high rpm's.  he carb has a lot of nice features for the price also.

    Couple of note though:
    1. I run a performer manifold, had clearance issues with manifold casting and required me to add 1/2 spacer plate to gain clearance.
    2. Bracket for throttle stud appears to be closer to carb that eddy's is.  This made the throttle cable and trans kick down at an angle that may bind up.  I could not find a long enough stud to use so I made one with the help of a local machine shop.  Basically took a hardened bolt about 2 1/2 inches and machined it down to work.
    3. QuickFuel was very helpful with the tech side of the carb, however absoutly no help with the stud issue.

    Overall I noticed a huge improvement with the quickFuel carb. :bigsmile:

    Good Luck!
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    Offline Chryco Psycho

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    Re: carb recomendations please, have new eddy 750 it just sucks
    « Reply #5 on: July 27, 2008 - 01:03:25 PM »
    Proform is good too , the problem with eddys is if you are making low vacuum there is no way to change the air bleeds to get the carb to respond well , anything with adjustable air bleeds is light years ahead of eddys carbs
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    Offline 71chally416

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    Re: carb recomendations please, have new eddy 750 it just sucks
    « Reply #6 on: July 27, 2008 - 01:36:39 PM »
    An Eddy carb shouldn't need too much calibration with a mild motor like his.  No way it should "fall on it's face" or pop or surge. Sounds like somebody did something to it they shouldn't have did, like put the wrong metering rods in or the springs that go under them. I'd make sure it has all the stock parts in it before I go buy something else. This is the calibration for the Performance carb. Make sure you don't have the "Fuel economy" calibration.

     Metering Jets – Primary .113, Secondary .107; Metering Rods – .071 x .047; Step-Up Spring – orange (5" Hg) 
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    Offline FJ5_440

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    Re: carb recomendations please, have new eddy 750 it just sucks
    « Reply #7 on: July 27, 2008 - 05:40:43 PM »
    I like the Proform or quickfuel carb better than the Eddie too, but there are a couple quick and cheap things you can try to get it to be better.  If your carb guy tuned it and it is still as bad as you say, he probably doesn't do too much with Edelbrock carbs.  I am certainly no expert but have messed with the AFB and AVS carbs quite a bit. 

    Give it the right tune and it will probably be much better.  Probably never as responsive as a Holley type carb, but better than it is.  Check the float level !!  Check it again!! Make sure the accelerator pump linkage is in the top hole.  Make sure the step up spring is rated only a little lower than your in-gear idle vacuum reading.  Out of the box, these things are often too lean (especially the 1411 with electric choke),  have too weak of a step up spring, don't have enough pump shot, and have excessive float drop as well as an incorrect float level.  These can be addressed pretty cheaply.  The float level and accelerator pump linkage  is sometimes half of the problem and can be fixed for free in just a couple of minutes.  Changing the rods and springs in a 1411 carb to a pair of 1458s  with the appropriate spring for your vac readings will cost about 20 bucks and about 5 minutes.
    The air bleeds and pump shot system are a whole other problem which can't be addressed quickly or cheaply.  For trouble free cruising the Edelbrocks can be decent.  For maximum performance, look eleswhere, :2cents:
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    Offline 71chally416

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    Re: carb recomendations please, have new eddy 750 it just sucks
    « Reply #8 on: July 28, 2008 - 12:19:31 AM »
    The 750 Demon carb I have on my 416 needed jets 15 sizes bigger than stock on the primary side and 12 sizes bigger on the secondary side to get the EGT's in the ballpark on the engine dyno. Not exactly spot-on performance calibration from the factory. Once you start modifying everything stock carb calibrations go out the window.

    My experience with the ED carbs has been pretty good. A friend of mine with a '70 340 Dart (Cam/headers/Intake) borrowed my box-stock 750 I had on the original motor in my car and dropped his ET 3 tenths from the best it ran with a Proform 750. He wouldn't give it back and bought it from me. We had another motor on the dyno, a high 10 second 440 from a bracket car. Using an 800 EPS carb it made within 5hp of the track jetted Holley 850DP the guy has been using. It's very likely it would have had better numbers than the Holley if we would have played with the jetting and metering rods.
     
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    Offline mikerallye

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    Re: carb recomendations please, have new eddy 750 it just sucks
    « Reply #9 on: July 28, 2008 - 04:33:57 PM »
    the lighter (Blue) step up springs make the secondary kick in earlier right?
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    Offline mikerallye

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    Re: carb recomendations please, have new eddy 750 it just sucks
    « Reply #10 on: July 28, 2008 - 05:11:36 PM »
    Look at the coil, I had the backfiring issues last week, the coil was bad.  :2thumbs:
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    Offline 71chally416

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    Re: carb recomendations please, have new eddy 750 it just sucks
    « Reply #11 on: July 28, 2008 - 07:31:05 PM »
    Quote from: mikerallye on July 28, 2008 - 04:33:57 PM
    the lighter (Blue) step up springs make the secondary kick in earlier right?

    I believe it's the opposite. Heavier springs will overcome the vacume and push the metering rods up out of the jets quicker (richer mixture) and lighter springs will push them up later (make it leaner) The tuning kits for them are cheap and anyone who has one should buy one.
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    Offline Harts56

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      • 70 Challenger Convertible
    Re: carb recomendations please, have new eddy 750 it just sucks
    « Reply #12 on: July 28, 2008 - 08:32:50 PM »
    This is from Eddelbrocks website on how to adjust the carb:
    http://www.edelbrock.com/automotive_new/mc/carbs_acc/pdf/carb_owners_manual.pdf

    It is pretty good, you will need to get the calibration kit #1411 for the Performer 750.  With some trial and error you should be able to dial it in better than what you have!  Cost is about $50 at Summit Racing.

    Good luck!
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    Offline Chryco Psycho

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    Re: carb recomendations please, have new eddy 750 it just sucks
    « Reply #13 on: July 29, 2008 - 01:43:33 AM »
    the metering rods & springs are like a power valve they increase enrichment under low vacuum allowing the rods to rise & more fuel to enter , the heavier the spring the earliewr the rods rise , if the spring is too heavy & the vacuum too low the rods will nto stay down at idle causing a rich & poor idle quality.
    None of this has anything to do with the secondary opening , the secondary opens when the engine creates enough air flow to pull open the counterweighted flaps in the rear venturi , this is solely determined by the balance between air flow & weight holding them closed , . in every carb I have worked on I have drilled a 1/4" hole in both counterweights at the furthest distance from the pivot shaft to decrease weight so the flaps open sooner , so far I have never encountered a bog doing this so I am Sure more weight can be removed but what a pain in the butt to do it , & when you go too far you r better have either a welder handy or thread the hole & insert a bolt , Holley had a better Idea with interchangable springs , or the AVS & TQ with an adjustable spring on the air flap
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