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  1. #1

    Default Looking for help for Holley 570 SA CARB EXPERTS

    I am new to tuning carburetors and i am building a motor for my 1985 mustang gt convertible.

    I am looking for what i should do for a base tune on my holly 570 street avenger carburetor.

    The carb is originally from a custom boat with a chevy 350 and i had it running on the stock 5.0 f.i. HO motor but never got it to work good.

    The new motor's setup is, 1988 factory 302 block, Factory 1985 Rotating assembly with new rings and bearings, arp main bolts, head bolts, rocker studs and rod bolts. It is running a Comp 35-226-3 Cam and lifters:

    Cam Specs:
    lift: .512, .512
    231,231 duration @.050
    110 lsa
    Springs:
    comp 972-16
    Pushrods:
    Comp 3/8"
    Rocker arms:
    Comp 17044-16

    Heads:
    Factory 1967 351w
    Intake valve: 1.870
    Exhaust valve: 1.570
    Compression ratio: ~9.4:1

    Distributor:
    Pertronix Flamethrower ignitor II

    Intake Manifold:
    Weiand Stealth Intake (non-polished)

    The car will weigh between 2500 and 2800 lbs with a wct5 from a 1986 svo and factory 8" rear end with a 3.27:1 Ratio
    it will be running premium only. And i want it to be as driveable as possible given the cam. I dont want it to break 350hp and it will not be running slicks or likely even performance tires.


    I am looking for what would be a good starting place in terms of jet sizes, secondary spring, squirter sizes, squirter cam sizes, power valve, everything.

    I appreciate help thank you.

    Additionally i am aware of the downsides of this build and do not need to be reminded lol This is just the engine i am making to get the car running.

  2. #2

    Default

    I pulled my 570sa straight from the box and it was perfect with the edelbrock Performer Rpm top end package. Best carb ever in my book.


    Sent from my iPhone using Tapatalk

  3. #3

    Default

    That's basically the recipe for the Joe Sherman Racing Engines' (dual plane intake version) ~380 hp 302... with 2 degrees more lobe separation, about a point less compression ratio, and minus up to about 300cfm of carburetor airflow... IMHO, a common, inexpensive LIST-3310 750cfm would work very well on yours...

    Regardless, what's the LIST # on the front of the choke shroud? There are discrepancies between the handful of list numbers for "570" Street Avengers within all of their marketed and published physical dimension and calibration information. One lists a combination of all four venturi being 1-3/32" and all four throttle bores as 1-1/2", which happen to be the same as an early LIST-1848-1 that's listed as having an airflow rating of 465cfm... and other list numbers are a combination of primary venturi being 1-1/4" and secondary venturi being 1-5/16" and all four throttle bores as 1-9/16", which happen to be the same as most any 600cfm four barrel, as well as "670" Street Avengers...

    Rather than relying on their (unreliable) information for jetting and such per venturi/bore dimensions, please provide yours' LIST #, it's bore and venturi dimensions, and what components are presently installed within it... and then we should be able to at least establish a good starting point for it's calibration...

    The fact that it isn't new (new, in my experience, not necessarily being a better situation) means jetting or other items may have been changed or calibration orifices (bleeds, restrictions, etc) resized. If you happen to have small (#61-80 & #1-60) precision drill bits and a dial or digital caliper to be able to measure air bleeds, idle feed restrictions, and power valve channel restrictions, that would be even better for verifying/establishing it even being in the right ballpark for "tune"...
    Last edited by Walking-Tall; 12-07-2017 at 02:16 PM.
    Mike
    1986 Mustang convertible ---> BUILD THREAD
    1983 Mercury Cougar LS
    1986 Ford Thunderbird ELAN
    1966 Ford Fairlane sedan
    1966 Ford Fairlane GT
    1981 Mercury Marquis Brougham
    1980 Capri RS Turbo
    1971 Mustang
    1974 Pontiac LeMans

  4. #4

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    It has been modified and i have bought it used from a boat. The number on the front of the choke shroud is 80570-2857. I know from the seller that the jets have been changed but nothing else that i know of. I appreciate the help. It has the hooked bowl vent tubes common for boats, i don't know if that helps. I have a OK understanding of carburetors but i have not really dug deep into what they want for different parameters. I am not trying to make crazy power right now, More of just trying to get the car on the road.
    Last edited by spamynator_1; 12-12-2017 at 12:54 AM.

  5. #5

    Default

    Just sayin', if the previous owners' modifications did not include any resizing of pressed in orifices (primary idle feed restrictions or air bleeds up top) or power valve channel restrictions for it's former marine application, then verifying that (and/or installing) the jets and such that Holley put in it originally should be a good starting point. The "numerical listing" indicates it's the smaller four barrel, marketed as "570" cfm, but with all four venturi at 1-3/32" and all four throttle bores at 1-1/2" (other same size carburetors previously listed as 450-ish cfm)... eether, either, they list #54 primary and #65 secondary main jets, an 8.5"Hg primary power valve, a #31 accelerator pump shooter, and the "plain" color secondary spring.

    See page 12 for specs... http://documents.holley.com/199r10219-3rev5.pdf
    Mike
    1986 Mustang convertible ---> BUILD THREAD
    1983 Mercury Cougar LS
    1986 Ford Thunderbird ELAN
    1966 Ford Fairlane sedan
    1966 Ford Fairlane GT
    1981 Mercury Marquis Brougham
    1980 Capri RS Turbo
    1971 Mustang
    1974 Pontiac LeMans

  6. #6

    Default

    As well, opening it up and checking it over and rebuilding it with a good verified baseline isn't about "trying to make crazy power", but much more about just having it function correctly, and not continuing with any kind of situation of "i had it running on the stock 5.0 f.i. HO motor but never got it to work good"...

    What, if anything, did you have to do to have it running at all? The details of what needed doing can be clues... and I've run across some pretty whacked out quality and manufacturing issues (restriction/bleed sizes and/or presence at all, etc.) most explicitly with post-2000 carburetors...

    A list of sorts of a few of the finicky things to check that are missed or screwed up with some of the newer stuff:
    - "emulsion" bleeds (lower two #5 & #17 (BTW, if the carburetor does not have down leg boosters, the single uppers (usually called kill bleeds) of #5 & #17 are not required)) actually drilled 0.026-0.028" through into the main wells. I've seen them with two drilled on one side and the two on the other side not drilled, making for a cluster bleep main circuit (worse yet, this is also the WOT) fuel curve.
    - upper main and idle air bleeds at carburetor throat entrances are clean and clear, and the drilled passages below them are actually bigger than each bleeds' restriction size. I've heard about and seen the passages below being smaller, making for cluster bleep function impossible to tune out with adjusting things.
    - make sure the inner idle mixture screw passages that the idle mixture screw tips go into the primary metering block, that are between #10 & #11 in the image, and between #22 & #23 in the image, are measured and are somewhere close to 1/16"... and your (traditional) idle mixture screws have non-blunt sharp smooth tips. I've found the drilled passages in newer blocks to be nearly 1/8", making for a cluster bleep of non-adjust-ability.
    - ... when the other things come to me, I'll be back, lol...

    Last edited by Walking-Tall; Yesterday at 01:40 AM.
    Mike
    1986 Mustang convertible ---> BUILD THREAD
    1983 Mercury Cougar LS
    1986 Ford Thunderbird ELAN
    1966 Ford Fairlane sedan
    1966 Ford Fairlane GT
    1981 Mercury Marquis Brougham
    1980 Capri RS Turbo
    1971 Mustang
    1974 Pontiac LeMans

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