Carb size question
+ Reply to Thread
Page 1 of 7 1 2 3 4 ... LastLast
Results 1 to 14 of 91

Thread:
Carb size question

  1. #1
    Senior Member carreradude's Avatar
    Join Date
    Dec 2008
    Location
    Rancho Cordova. CA
    Posts
    656

    Default Carb size question

    Hey guys. I am kinda new here and have enjoyed and learned from a lot of posts here. I can see there is a lot of talented peeps here that build engines and entire boats. First I need to tell you guys about my engine combo and what it is in....It is a chevy 496. 10.2 to 1 comp. I am running 396 heads with the 1.88/2.19 valves 96cc chambers, flat top SRP forged pistons, Eagle "H" beam rods, Eagle steel crank, the cam is a hydrolic roller
    242-254 @ 50 .670 lift with 113 sep. and roller rockers on top. Exhaust is thru transom Bassett headers. I am running a Weiand tunnel ram with two holley 450's on it. It turns a berk JG with a Berk "A" , a stage 1 blue print with a stuffer (blue print was CP Performance) to 5200 rpm with a place diverter. It is a 1991 Carrera Eclipse 21 ft shallow "V". I have only had a gps read back when I had a tired 454 with the same pump combo and it spun 5000 rpm and that was 69 mph. I am guessing 72 ish with the 496. I can run a long time before I need fuel. A lot of peeps say I need to step up to bigger carbs. Let me say I am not looking to get some insane speed here. My deal is acceleration....quick and hard. Do you guys think bigger carbs are worth my time? I like to be pinned to the seat more than MPH. It throws you back pretty good as it is now. I would like to hear some thoughts on what you guys may think. Oh, This is just a lake and river boat. Thanks in advance!!! Mike

    Last edited by carreradude; 12-30-2008 at 10:47 PM.

  2. Remove Advertisements
    PerformanceBoats.com
    Advertisements
     

  3. #2
    Senior Member ol guy's Avatar
    Join Date
    Mar 2008
    Location
    Lake Elsinore Ca
    Posts
    3,856

    Default

    With the combo you say you are running I would imagine that your'e plugs come out looking brand new!!! If you look at the plenunm and the feul you are toosing at the motor you are running then the carbs are great for a SMALL BLOCK. I would not run anything smaller than a pair of 750's on that set up. In a word yes you are way lean,Okay more than one word but If you think it tosses you back in the seat now then feed it and go change you're shorts and call back in the morning.

  4. #3
    Senior Member carreradude's Avatar
    Join Date
    Dec 2008
    Location
    Rancho Cordova. CA
    Posts
    656

    Default

    Hey Old Guy. Thanks for your response. I have been down the dragstrip here in Sacramento quite a few times with my pavement pounder. I don't mean ANY disrespect, but I can't see a 496 sucking down more than 900 cfm at 5200 rpm. I belive (imo) I will just burn more fuel with bigger carbs
    with little to no performance improvement. I do understand I may be wrong. All I ask is it to be explained to me. Thanks for any input!!

  5. Remove Advertisements
    PerformanceBoats.com
    Advertisements
     

  6. #4
    Senior Member hotbo's Avatar
    Join Date
    Feb 2008
    Location
    lake Ouachita AR
    Posts
    4,677

    Default

    put a set of 600s on it and you will still conserve fuel and get better response in the mix.if you put 750s thats even better but i bet youll be happy with 600s.jets love more fuel and air and with those carbs in a 496 package you are chocking the stroker downsome will say even bigger but you do have a large boat and a nice looking boat by the way.good luck hope this helps.travis

  7. #5
    Senior Member
    Join Date
    Dec 2007
    Location
    Tri-Cities, TN
    Posts
    1,681

    Default

    I think a set of 750's would be your best bet. The air speed that must be in the venturi has to be just insanely fast with the combo over 5000 rpm and those 450's which would lead me to believe your not getting good atomizing of fuel. You need to slow the air speed down with some 750's and I bet she'll pick up power everywhere.
    Chris Straub
    Straub Technologies

    3HP is an A$$ Whooping!!! JW

  8. #6
    gn7
    gn7 is offline
    Senior Member gn7's Avatar
    Join Date
    Jan 2008
    Posts
    25,975

    Default

    Quote Originally Posted by ol guy View Post
    With the combo you say you are running I would imagine that your'e plugs come out looking brand new!!! If you look at the plenunm and the feul you are toosing at the motor you are running then the carbs are great for a SMALL BLOCK. I would not run anything smaller than a pair of 750's on that set up. In a word yes you are way lean,Okay more than one word but If you think it tosses you back in the seat now then feed it and go change you're shorts and call back in the morning.
    please explain how a a pair of 450s equates to the term "lean"



    100% free webcam site! | Awesome chicks and it is absolutely free! | Watch free live sex cam - easy as 1-2-3

  9. #7
    The Man cordog009's Avatar
    Join Date
    Jan 2008
    Location
    East Texas
    Posts
    1,788

    Default

    How about a pair of 660cfm Holley 4160s like I have on mine? They are a compromise between the 600s and 750s.


    1984 Youngblood TX-19 SOLD

  10. #8
    gn7
    gn7 is offline
    Senior Member gn7's Avatar
    Join Date
    Jan 2008
    Posts
    25,975

    Default

    Quote Originally Posted by cordog009 View Post
    How about a pair of 660cfm Holley 4160s like I have on mine? They are a compromise between the 600s and 750s.
    and have all the drivabilty of a brick with a hole drilled in it.



    100% free webcam site! | Awesome chicks and it is absolutely free! | Watch free live sex cam - easy as 1-2-3

  11. #9
    E-7 Sheepdog (ret) SmokinLowriderSS's Avatar
    Join Date
    Dec 2007
    Location
    Newton Ks.
    Posts
    6,834

    Default

    I think if you want to burn more fuel and gain nothing noticable, bigger carbs are a perfect idea.

    Go much bigger than the 900CFM you are already trying to shove thru stock, closed-chamber heads, and you will only "negatively enhance" your driveability.

    I'm sure someone will sugggest twin Dominators tho.

    IMO you'd be better off with a better head, as far as "bang for buck" gains available.
    "As democracy is perfected, the office of president represents, more and more closely, the inner soul of the people. On some great and glorious day the plain folks of the land will reach their heart's desire at last and the White House will be adorned by a downright moron."
    H.L. Mencken

    OBAMA: Some people deserve this.
    The rest of us are being dragged along kicking and screaming.

  12. #10
    The Man cordog009's Avatar
    Join Date
    Jan 2008
    Location
    East Texas
    Posts
    1,788

    Default

    Quote Originally Posted by SmokinLowriderSS View Post

    IMO you'd be better off with a better head, as far as "bang for buck" gains available.
    That's what I was thinking as well.


    1984 Youngblood TX-19 SOLD

  13. #11
    Senior Member MACHINEHEAD1's Avatar
    Join Date
    May 2008
    Posts
    473

    Default

    First I would recomend a good 'ol vacuum gauge connected to the base plate. This will give you a good idea of how hard those little carbs are being sucked on at [email protected]. You probably have a 560hp combo there. Myself and many others have made over 640hp w/496 and a 800dp. I have worked with these 450s alot. They are a little lean out of the box for the combo I had run them on. A secondary metering plate change was all that was needed. Now there is a adj. plate available from Percy's I think. 750s would have the HP advantage on the big end. Fuel consumtion is a non issue at part throttle. It still takes, lets say 400cfm to cruise your boat, so total carb size doesnt matter at cruise. The bigger carbs just arent open as far.

  14. #12
    Senior Member CHEVY JET's Avatar
    Join Date
    Mar 2008
    Location
    St. Charles, IL
    Posts
    976

    Default

    THAT IS A REAL GOOD LOOKING BOAT!! I AGREE JETS DO LIKE FUEL, MY DAD HAD A 78 KONA 21' DAY. HE HAD A 950 HOLLY ON IT, TOOK IT OFF AND PUT A TUNNEL RAM ON IT WITH TWIN 600 AND GOT BETTER GAS MILAGE. MORE FUEL ISNT ALWAYS MORE FUEL CONSOMPTION. SOME TIMES IT TAKES MOER FUEL TO MAKE A SMALLER CARB WORK RIGHT. IMO

  15. #13
    Senior Member hotbo's Avatar
    Join Date
    Feb 2008
    Location
    lake Ouachita AR
    Posts
    4,677

    Default

    all of these good points.but the 450s are to smalltalk to chris straub thru pm he is a super guy and he can tell ya what he means by velocity and such.yes the 750s will be a good choice no matter the head combo.


    smokin so whats your excuse for the slowriderjust pokin hope all is well.\


    those damn cfm calculators are good for street srtip stuff imo jets are different remember this when thinking big end or low end hell there is no low end when you mash it if it turns 5200 rpm it turns it instantly

  16. #14
    Cas
    Cas is offline
    Angry American Cas's Avatar
    Join Date
    Jan 2008
    Location
    NorCal
    Posts
    3,103

    Default

    this is the carb Mike is running-



    Carburetor Flange: Square bore Choke: None Fuel: Gasoline Secondary Type: Mechanical New or Remanufactured: New Fuel Inlet: Single CFM: 450 Carburetor Finish: Dichromate Ford Kickdown: No Throttle Linkage Type: Universal Quantity: Sold individually. Notes: This has a mechanical secondary, but no secondary accelerator pump circuit. It is designed for a mulitiple carburetor application ONLY, it will not function properly on a single carburetor application.
    actually 2 of them.

+ Reply to Thread
Page 1 of 7 1 2 3 4 ... LastLast

Quick Reply Quick Reply

Register Now

Please enter the name by which you would like to log-in and be known on this site.

Please enter a password for your user account. Note that passwords are case-sensitive.

Please enter a valid email address for yourself.

Please select your insurance company (Optional)

Log-in

Tags for this Thread

Digg This Thread

Posting Permissions

  • You may post new threads
  • You may post replies
  • You may not post attachments
  • You may not edit your posts
  •  
 

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95