Holley Carb

Discussion in 'Holley' started by NEBuick430, Apr 25, 2018.

  1. NEBuick430

    NEBuick430 Member

    Hello all, I am a new member. Looking for some input on my project. I have a 67 Skylark with a stock long block 430 engine and turbo 400 transmission. This is my first time working on Buickā€™s. The long block is all stock 430. I have headers thru 2.5 in. Exhaust into Pypes race flow mufflers. I have a Poston Hyd. Cam, .542 lift and 312 Int. and 332 Ex. duration. It is Poston grind GS 110. Old school Edelbrock B4B intake. My ignition is an old school Mallory mechanical advance dual point distributor. The transmission has a street converter as well. Right now I have both a 750 and 850 DP Holley with mechanical secondaries and four corner idle screws. Which size Carb. Should I use ? I read on the forum that I may need the Summit G1420 adaptor plate to use one of these Holley carbs on the intake manifold I have. Is this something I need to get ? Depending on carb recommendation what should I start with for baseline carb jetting and power valves front and rear, or no rear power valve ? Also what are your recommendations for an initial timing setting with the distributor I have. This is a street driver to just cruise around in. Any input from you Buick guys would be greatly appreciated. Thanks
     
  2. OHC JOE

    OHC JOE BUILDIN A 1970 GSX CLONE

    Welcome from so cal you will find this place addicting.
    You will also get an answer and opinions soon post some pics of your car.
     
  3. DEADMANSCURVE

    DEADMANSCURVE my first word : truck

    and post a pic of your carbs and intake opening/mount area if possible . the original B4B's were a square bore ( holley edelbrock , even oval openings) pattern - no adapter needed . the newer ones are dual pattern ( quadrajet spreadbore style or square bore ) - no adapter needed - but they do recommend a flat plate/gasket kit to avoid vac leaks ( like the #G1420 ) . and at some point you may want to try a 1" spacer under carb , sometimes benificial depending upon your combo .
    are your two carbs unmodified or has someone "improved" them ? let me have the part #'s from the front of choke tower on them and i can let you know what oem spec jetting etc is . i would recommend starting out there on whichever carb you want to try to give you a base line . make minor mod's from there .
    i would be tempted to try the 750 first . might be a little crisper down low for test driving and may not get you into an over rich condition . if you are going to push the car ( not like in "i own a ford" ) from time to time the 850 will not be too big .
    if in the future you upgrade your intake then you should consider a mod'd quadrajet from one of the rebuilders on here . good combo of performance and economy . but since you already have the holley's might as well see how you like them . just depends upon your direction with car .
     
    Last edited: Apr 26, 2018
  4. NEBuick430

    NEBuick430 Member

    Thanks for the reply. My B4B intake is a dual pattern mount for Holley or QJET. I did buy the Edelbrock sealant plate kit today so I can avoid vac leaks. I am sure someone has been into the carbs at some point. The 750 says 4779/7 with the numbers 2550 underneath. The 850 says 4781/2 with the numbers 0496 underneath. I know the 850 has 82 primary jets and 90 secondary jets with a power valve block off plug in the rear. Have not looked into the 750 yet. My intention down the road is to get a prepped QJET. I saw a recommendation for QJET from Everyday Performance. I live about an hour from him so I may try them for the QJET. I did some more reading on the forum and saw timing recommendations of around 12 degrees for initial setting. How does that sound ? Any info. You can provide is greatly appreciated. Thanks
     
  5. DEADMANSCURVE

    DEADMANSCURVE my first word : truck

    4779-7 is a pretty new series 750 and should be 4 corner idle unless someone switched metering blocks .
    4781-2 is a early series 850 and should be 2 corner idle . -3 and newer we're 4 corner . Alot of the earlier metering blocks had the carb # stamped on them so that would be good if there . As far as originality anyway .
    I'll check spec's and get back to you .
    edit : yeah , ken is a good choice for a QJ if you decide to go that way . he did an 800 for me ( 350 ) , started right up , sounds good n crisp , no road test yet but his reviews are always stellar . met him a few times , nice guy .
    back to holley chit chat -
    4779-7 : fr jets 71 , rr jets 80 , power valve 6.5 , fr nozzle 28 , rr nozzle 31 , acc pumps - both 30cc .
    4781-2 : fr jets 80 , rr jets 80 , fr power valve 6.5 , rr power valve 6.5 , fr nozzle 31 , rr nozzle 31 , fr acc pump 30cc , rr acc pump 50cc .
    that info is out of an older holley catalog that has a ton of useful info inside , not just pics and part numbers . same spec info found online at holley website - except easier to read ! us old guys need our big print !
    there is some basics for you so if you tear one or both apart you'll be able to make an educated guess if anyone has totally put them outa whack .
    feel free to contact me back if you need info etc . or there are plenty of holley users on here that can guide you also . the ones running the big blocks with a similar setup to you could be extra helpful concerning jetting etc .
    and just reread your second post - on a street car holley sort of discourages the use of no rear power valve . that's probably why the rear jets are bumped up , to compensate for the lack of power valve fuel being added . sort of think of it like vacuum secondary - gets it when it needs it .
     
    Last edited: Apr 27, 2018
  6. NEBuick430

    NEBuick430 Member

    Thank you very much for the info. I think I will take the 750 Holley and set it back up to the factory specs then go from there. I will post my results of how the car runs.
     
  7. DEADMANSCURVE

    DEADMANSCURVE my first word : truck

    great , contact me if you need anything . if not sure about a part etc just post up a clear pic with numbers etc info .
     

Share This Page