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  •  » Carburetor size and brand selection

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    3/07/2023 6:10 PM  #1

    kardad
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    From: Lexington Ky
    Registered: 12/03/2019
    Posts: 267

    Carburetor size and brand selection

    Ok, this is basically a multipile part opinion/educational question. I am in the planning stages of my truck project:
    1976 F100
    Crown vic front
    Explorer 8,8  w/ 3.73 LS (Because I have it, may change to a 3,55 or even 3.08 later)
    351 (393) low RPM cruising torque monster
    4R70W Electronic Auto Overdrive (1998 Mustang 3.8 model)

    I want to build a nice ideling cruising truck that has tons of torque with great throttle response and will never see over 5000 RPM and realistically 4000 RPM (probaly live in the off idle -2500 RPM).

    I have never built anything with an auto, always a manual.

    I plan to run a 600 CFM carburetor, I know this is on the small size by some peoples thinking, but I like the throttle response that this size should provide over a 750. SO THAT IT OPINION QUESTION NUMBER ONE

    From what I have read, a vacuum secondary carb will work better with an auto trans than a mechanical secondary. THAT IS OPINION QUESTION NUMBER TWO

    I have had decent luck with both the Summit Brand Carb (Holley/Autolite knock-off), as well as the Eldebrock Carbs. I like both of these due designs because they won't leak as a Holley may do. but neither of them have been perfect either. THAT IS THE FINAL OPINION QUESTION

    Tons of Carburetor experience on here, and NO I dont want to go EFI. I need to determine what carb I plan to use in order to order the TPS (Throttle Position Sensor) kit for the transmission controller. This Autoomatic Trans thing is new ground for me.


     

     

    3/07/2023 9:20 PM  #2

    Bolted to Floor
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    From: Houston, Texas
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    Re: Carburetor size and brand selection

    A 600 seems small for that size motor. What about a 650? Should still get the throttle response you are looking for.

    I would stick with a vacuum secondary. It should get you better manners and economy, or what little there may be.

    Plenty of folks have had good and bad luck with all brands you listed. So, get whichever one you like to tinker with.

    John  -- 67 Mustang Coupe 390 5 speed
     

    3/07/2023 9:55 PM  #3

    Rudi
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    From: Stuck in the 50's Welland Ca
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    Re: Carburetor size and brand selection

    Most Holley leak issues are caused by cheap/ incorrect gaskets.
    My recommendation is a 670 Street Avenger, the aluminum ones are nice and light compared to the zinc ones.

    Good work ain't cheap, Cheap work ain't good!   Simple Man
     

    3/08/2023 11:14 AM  #4

    6sally6
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    From: Surfside Beach,SC
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    Re: Carburetor size and brand selection

    600 CFM carb on an engine that size (and geared like you have it) will be like puking with a rope around your neck!
    Your line of thinking ....put a one barrel on and the low end torque will be GREAT!....WORNG.

    A 750 Edelbrock (I like those and am familiar with) will have 'small' primarys for great low end torque and larger VACUUM controlled secondaries for "eyeball-flattening" acceleration as the engine needs it. In stock form the carb WILL NOT let you over-carb the engine! It will let in more fuel only when the engine can use it. (They CAN be tinkered with butt thatz another post)

    Ya see....larger cubic engine engines need primaries large enough to idle correctly. Too small and the air will be 'whistling through' the primaries sounding like an old Eastwood spagetti-western theme song (use your imagination!!)

    Quadra jet carbs from the 60's &70's were perfect for hot street engines (in design!). small primary HUGE secondaries.
    Edelbrocks are pretty close to that.
    (When we gonna discuss camshafts !!! )
    6sally6

    Get busy Liv'in or get busy Die'n....Host of the 2020 Bash at the Beach/The only Bash that got cancelled  )8
     

    3/08/2023 12:31 PM  #5

    MS
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    From: Canyon Lake, Texas
    Registered: 1/24/2013
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    Re: Carburetor size and brand selection

    600 is great size for what you want.  Definitely vacuum secondary.

    Why do people say Holleys leak?   That is all I have ever had and have never had one leak in over 40 years.

    Summit is a really god carb but I hate the fuel linkage that can only me made to enter on passenger side.

    Edelbrock is just wrong look for a Ford, but can run quite well.

    Holley is the way to go. Looks right and you can make it run the way you want.  Use the Boss 302 fuel lines on a center pivot bowl setup with fuel inlet on driver side where it belongs.

    Money you enjoy wasting is NOT wasted money... unless your wife finds out.
     

    3/08/2023 12:32 PM  #6

    kardad
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    Re: Carburetor size and brand selection

    Thanks Sal for the info, 

    I understand and agree for the most part. I don't think the carb size will necessarily impact the amount of torque, but the throttle response at low RPM. I know I need to keep the velocity up for the carb not to stumble at low RPM. I do like the thought of a spread Bore for that reason.

    When it comes to sizing, all of the sizing charts are based on operation RPM and cubic inches, and I know I won't be over 5000 RPM and probably much lower. Just curious how most of you tend to size your carbs. My 331 with AFR heads loves to operate in the 5000-6500 RPM range and I run a 600 on it.

    As I said I haven't ever selected a carb to use with an automatic, but from what I gather a vacuum secondary carb would work better for street use. I want to drive this truck a LOT and want great street manners and don't care if I give up some HP.

    I like the tunability of the Edelbrock, but all of them appear to have mechanical secondaries.

    Thanks, and I am enjoying the education and experience from all.
     

       •Thread Starter
     

    3/08/2023 1:00 PM  #7

    MS
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    From: Canyon Lake, Texas
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    Re: Carburetor size and brand selection

    Edelbrock secondaries are mechanical, but they have a vacuum controlled air regulator like a choke blade or some otherwise weird added stuff.

    Ford used 600 on big cube engines.  As you surmise, better throttle response.

    Money you enjoy wasting is NOT wasted money... unless your wife finds out.
     

    3/08/2023 1:52 PM  #8

    kardad
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    From: Lexington Ky
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    Re: Carburetor size and brand selection

    Thanks for the advice, From ALL,

    I have had decent luck with the Edelbrocks but as stated, it just looks wrong and that is why I had used the Summit carb. I have had experience with 3 of the Summit carbs, one was great, the other 2 weren't bad but had consistent idle issues as well as the choke linkage was problematic at times.

    Let's say I go Holley, are there any suggestions in the 600-650 size? I want great drivability over raw performance.

    The reason I am trying to make a decision so early in this project is I have to know what carb I'm going to use to order the correct Throttle Position Sensor Kit from US-Shifts to work with the 4R70W controller.

    My plan is to get the trans in and operating to work through any bugs before building and installing the motor. So I will be using the carb on a stock 302 for a few months. I want to work through the driveline a piece at a time, so I know where to start with any issues vs my 68 that I replaced absolutely everything at one time, and I truly believe that's why I'm still chasing the dam vibration from one end to the other.
     

       •Thread Starter
     

    3/08/2023 4:28 PM  #9

    MS
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    From: Canyon Lake, Texas
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    Re: Carburetor size and brand selection

    I have a 600 vac sec Holley on my 331 in the 69.  I can give you pretty much perfect jet size, power valve size, pump cam and squirter size for the small block. The carb I built for it performs flawlessly and the electric choke works perfect.

    Money you enjoy wasting is NOT wasted money... unless your wife finds out.
     

    3/08/2023 5:14 PM  #10

    Ron68
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    From: Mukilteo, Washington
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    Re: Carburetor size and brand selection

    kardad wrote:

    Thanks Sal for the info, 

    I understand and agree for the most part. I don't think the carb size will necessarily impact the amount of torque, but the throttle response at low RPM. I know I need to keep the velocity up for the carb not to stumble at low RPM. I do like the thought of a spread Bore for that reason.

    When it comes to sizing, all of the sizing charts are based on operation RPM and cubic inches, and I know I won't be over 5000 RPM and probably much lower. Just curious how most of you tend to size your carbs. My 331 with AFR heads loves to operate in the 5000-6500 RPM range and I run a 600 on it.

    As I said I haven't ever selected a carb to use with an automatic, but from what I gather a vacuum secondary carb would work better for street use. I want to drive this truck a LOT and want great street manners and don't care if I give up some HP.

    I like the tunability of the Edelbrock, but all of them appear to have mechanical secondaries.

    Thanks, and I am enjoying the education and experience from all.
     

    I believe the 600 cfm Edelbrock 1406 on my 351W has vacuum secondaries.

    68 coupe - 351W, 4R70W, 9" 3.25 -- 65 convertible - 289 4v, C4, 8" 3.00
     

    3/09/2023 12:34 AM  #11

    Rufus68
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    From: Knoxville, TN
    Registered: 4/26/2017
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    Re: Carburetor size and brand selection

    If you are buying a carb, you might as well select a model that has annular boosters.  Check the specs before buying.  Annular boosters provide better atomization of the fuel.

    1968 T-code Coupe with a 302.  Nice car, no show stopper for sure, but I like it.
     

    3/09/2023 10:46 AM  #12

    6sally6
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    From: Surfside Beach,SC
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    Re: Carburetor size and brand selection

    A looooong time ago (when I was in band camp!) ,not really, Hot Rod recommended 600 CFM carbs for the SBF. 260/289/302
    As a young & dumb teen I did what "the experts"...(yeah right!)suggested.
    Come to find out now... 500 CFM carbs are what "the experts" (yeah right!) say.
    I would choose the 650 JUST IN CASE you ever decide to 'improve' on the performance later.
    FYI.....with that gear ratio...your main problem will be planting those rear tires when you nail-it...not over carburation.(Don't worry...you won't bog-it-down)
    6sal6

    Get busy Liv'in or get busy Die'n....Host of the 2020 Bash at the Beach/The only Bash that got cancelled  )8
     

    3/09/2023 9:50 PM  #13

    Nos681
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    Re: Carburetor size and brand selection

    MS wrote:

    I have a 600 vac sec Holley on my 331 in the 69.  I can give you pretty much perfect jet size, power valve size, pump cam and squirter size for the small block. The carb I built for it performs flawlessly and the electric choke works perfect.

     
    I am interested in the details.  The ‘69 did drive great.

     

    3/09/2023 10:23 PM  #14

    MS
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    From: Canyon Lake, Texas
    Registered: 1/24/2013
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    Re: Carburetor size and brand selection




    600 cfm vacuum secondary
    0-1850
    66 & 72 jets
    7.5 power valve
    #35 squirter
    Red accelerator pump cam

    Engine is 331 stroker with Edelbrock 1.90 heads and stock 1990 Mustang HO 5.0 roller cam with 289 Hipo exhaust manifolds and 2” exhaust system.  Pertronics distributor

    Last edited by MS (3/10/2023 10:10 AM)

    Money you enjoy wasting is NOT wasted money... unless your wife finds out.
     

    3/10/2023 5:37 AM  #15

    Nos681
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    From: Atlantic Mine, Michigan
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    Re: Carburetor size and brand selection

    I like your anti-rotation devices and carb setup info on the hold down bracket.

    What’s the additional bracing for on the rear stud?

    What gear ratio on this setup?  3.50 as I recall.

    Is that the ‘70 accelerator cable setup?

    Last edited by Nos681 (3/10/2023 5:45 AM)

     

    3/10/2023 8:39 AM  #16

    kardad
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    From: Lexington Ky
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    Re: Carburetor size and brand selection

    Not knowing Holley’s which model is that MS?
    I do like the fuel line location, it’s clean.

       •Thread Starter
     

    3/10/2023 10:13 AM  #17

    MS
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    From: Canyon Lake, Texas
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    Re: Carburetor size and brand selection

    Rear stud comes out right above the float adjustment screw on the rear bowl.  The contraption is made so the threaded ends of that old u-bolt clear that adjustment.

    I added the carb info on my post above.  Thanks for letting me know I had omitted the basic info

    Money you enjoy wasting is NOT wasted money... unless your wife finds out.
     

    3/10/2023 11:06 AM  #18

    TimC
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    Re: Carburetor size and brand selection

    KitchenAid LOL

     

    3/10/2023 11:38 AM  #19

    6sally6
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    Re: Carburetor size and brand selection

    TimC wrote:

    KitchenAid LOL

     

    Hod-dam ....these boyz don't miss nut'in !!
    6sal6

    Get busy Liv'in or get busy Die'n....Host of the 2020 Bash at the Beach/The only Bash that got cancelled  )8
     

    3/10/2023 1:05 PM  #20

    BILLY WALTON from GEORGIA
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    Re: Carburetor size and brand selection

    6sally6 wrote:

    TimC wrote:

    KitchenAid LOL

     

    Hod-dam ....these boyz don't miss nut'in !!
    6sal6

    LOL
     

    Its really me....I fixed my caps lock .
     

    3/10/2023 3:11 PM  #21

    MS
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    From: Canyon Lake, Texas
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    Re: Carburetor size and brand selection

    I figured, someday, somebody might get a kick out of that dishwasher nameplate I used as a device to align the air cleaner straight with the carb. The bracket at the rear vent works in conjunction and makes for a perfect alignment.

    Money you enjoy wasting is NOT wasted money... unless your wife finds out.
     

    3/10/2023 4:56 PM  #22

    kardad
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    From: Lexington Ky
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    Re: Carburetor size and brand selection

    Besides the obvious, what would be the downside of a manual choke, that’s all I had growing up and they always worked correctly right were you set it and when.
    One of the issues I have had with most, I guess modern carbs is a choke that was consistent.

       •Thread Starter
     

    3/10/2023 5:53 PM  #23

    6sally6
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    Re: Carburetor size and brand selection

    My biggest problem with 'manuel' chokes are............forgetting to close them when the engine warms up !
    Other than that.....no prob.
    6sal6

    Get busy Liv'in or get busy Die'n....Host of the 2020 Bash at the Beach/The only Bash that got cancelled  )8
     

    3/10/2023 8:42 PM  #24

    Rudi
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    Re: Carburetor size and brand selection

    Old lady goes to the dealership with an ongoing problem, tha car is getting very poor mileage and is running rough.
    After three visits the mechanic who could not find the cause asks to go with her on a test drive to see what’s going on.
    The mechanic sits in the pass seat, the blue hair gets in puts her seat belt on, pullers out the choke and hangs her purse on it.

    Good work ain't cheap, Cheap work ain't good!   Simple Man
     

    3/11/2023 1:24 PM  #25

    BobE
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    Re: Carburetor size and brand selection

    6sally6 wrote:

    My biggest problem with 'manuel' chokes are............forgetting to close them when the engine warms up !
    Other than that.....no prob.
    6sal6

    That's my experience also. (many, many years ago)  I have an electric choke, and have no issues with it.
     

    65 Fastback, 351W, 5-speed, 4 wheel discs, 9" rear,  R&C Front End.
     

     

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