Close



Results 1 to 24 of 24
  1. #1

    Default Reversing Holley "reverse-idle", and...

    A documenting/instruction, familiarization sharing of sorts, completely open to comments and questions. One man's trash can be another's treasure, etc...

    "Reverse-idle" with a Holley carburetor means simply that turning an idle mixture screw clockwise richens the idle (and transition) air:fuel mixture, and vice versa, turning it counter-clockwise leans the idle (and transition) air:fuel mixture. This is the opposite of the original, traditional function of the idle circuit mixture screws in Holley carburetors, and most every other carburetor that has adjustable idle mixture screws.



    I am not a fan of the "reverse-idle" system for a couple of reasons. First, and IMHO the most important for the utmost in fuel efficiency while operating your automobile, is the fact that the most efficient, optimum air:fuel mixtures required for an engine at idle and an engine and vehicle combination at off-idle/cruise can be (and usually are) very different, like approximately and ideally 13-14ish:1 at no-load idle, and upwards of 17:1 with light load part throttle acceleration and cruise, that which does not yet initiate the main circuit, the main jets and/or power valve enrichment. The two scenarios of idle and off-idle/cruise having their air:fuel provided for by a single circuit with only the ability to add additional air from an auxillary air bleed in the carburetor throat with the mixture screw, fixes the two scenarios closer together than the traditional separation of the two scenarios that always was within the design and execution of the original, traditional idle mixture screws and circuit capabilities. Second, at least for the time being, air is free. I would like to see every internal combustion engine inhale and burn as much air as it can take in, as opposed to excess fuel, and to be able to control and adjust exactly how little fuel as is required to be in the mix of air:fuel in each scenario for optimum efficiency, because it's the fuel that costs money. More and more money. An interesting exception I have seen for the use of "reverse-idle" is by "mrriggs" here on the forum, who created potentially the best of both worlds, with both "reverse-idle" adjustment for the leaner primary transfer slots' air:fuel mixture requirements and a separation by way of traditional richer idle air:fuel mixture requirement through adjustment with a 4180 throttle base with their idle mixture screws.


    The carburetor body for this little adventure happens to be an inexpensive Ford service replacement carburetor body that I acquired, a LIST-9051 (Ford part # D8PE-9510-BLA ( D8 meaning 1978 ), with a date code on it of "0864" (March 27th, 1974), which means that Ford or Holley took about 4 years to "design" or "engineer" this carburetor's modified, differently calibrated circuits (that took about 40 minutes to de-"upgrade" back to normal efficient function) for probably something like a 1978 460 van.



    This carburetor body has venturi and throttle bore diameters that are the same as any garden variety 600cfm vacuum secondary Holley carburetor, such as common 1850 or 80457 or 6619 carburetors, with 1-1/4" primary & 1-5/16" secondary venturi and all four throttle bores sized at 1-9/16"... which incidentally are the same dimensions as in such scary-named and expensive newer carburetors like "670" (in quotes because the 70cfm is blatant marketing nonsense) Street Avenger/Warrior etc...


    Briefly, another design aspect (incorporated I think in all Fox chassis 4180 Holley 4 barrels) I am not a fan of is an accelerator pump circuit transfer tube and o-rings between the metering block and the carburetor body. If the o-rings ever cease to perfectly seal, manifold vacuum that exists in the body's power valve vacuum chamber when the engine is running will suck fuel from it and straight into the intake manifold, which is an out-of-sight and hard to diagnose too-rich running issue, often mistaken for a "blown" power valve (another snowballed myth over decades of misinformation). I eliminate the tube and o-rings method with jb-weld with an oiled drill bit shank to create the simple traditional passage that seals fine and trouble-free then with a regular metering block gasket.




    Auxillary air bleeds in the primary bores blocked with brass socket set screws, and later with a smoothing swipe of epoxy:




    I removed brass plugs that were in the outer uppermost holes shown here, which lead up to where traditional mixture screws do the controlling of the idling air:fuel mixture:




    All 8 air bleeds were wonky, and drilled and tapped 8-32, and resized with what would be found in a common traditional 600cfm:




    Short lengths of lead solder were tapped down into the primary transfer slot passages in the base plate in order to block the tiny original constant feed primary idle restrictions located below each transfer slot in each throttle bore, and new traditional idle mixture screw controlled idle feeds were located and drilled 0.090"... as seen below where light shows through the transfer slots and the new idle feeds, and where light does not show through the original idle feeds...






    A traditional primary metering block was prepared for proper calibration of circuit orifice sizes and for adjust-ability:




    A little bit of clearancing of the jb-weld for power valve head clearance was necessary:




    Adjustable (main "jets" are now change-able 8-32 brass socket set screws) secondary metering plate:




    Assembled with a kit with non-stick gaskets, and reusable nylon needle'n'seat & float bowl gaskets. Ready to rock'n'roll:






    ... with the following safe starting point 600cfm "recipe" calibration within it:

    Last edited by Walking-Tall; 10-31-2017 at 06:40 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

  2. #2

    Default

    Another same design example, the LIST-6619-1 I got for a song and used the base plate on the above carburetor. The remaining parts of this will be remedied and will be used later when I need to do a (traditional idle) 600cfm vacuum secondary build. The accelerator pump transfer tube counter-bore will also be eliminated as with the carburetor above.

    If this were not a "reverse-idle" carburetor, the passages indicated below with arrows would lead to constant idle feed passages below the primary throttle plates in the base plate bores at idle, to deliver the idle air:fuel mixture from traditionally adjusted idle mixture screws.




    Within a "reverse-idle" carburetor, the passages above are drilled straight through into the primary bores, providing the "auxiliary" idle air bleed, the theory that can be seen in the 1st image of the 1st post above in this thread. They are at the upper arrows in the following image:



    ... and the traditional passages that would lead to constant idle feed passages below the primary throttle plates in the base plate bores for idle air:fuel mixture delivery are blocked with brass plugs that the bottom arrows indicate. Indicated by the middle arrows, IMHO, are another example of more to come useless and increased unnecessary variable features. They serve as air bleeds to the transfer slots at idle and small throttle openings, and make the transfer slots act like slots that are too long at greater throttle openings, providing more part throttle fuel for an increased amount of throttle opening... the polar opposite of what best fuel efficiency requires. These things may have helped certain vehicle combinations pass certain emission control tests, but they are the epitome of counterproductive to best fuel efficiency driving the vehicle. So, top to bottom by the arrows, these will be blocked, blocked, opened.


    I haven't even measured yet, but can visually tell that, just like the above carburetor, the primary idle air bleeds (green arrows) are probably too small and the secondary idle air bleeds (purple arrows) are definitely too big, so they will be made adjustable and resized appropriately. The red arrow shows a secondary opening signal passage bleed, a delay... IMHO, the only PREDICTABLE variable we need for when the secondaries open is the spring inside the vacuum secondary diaphragm housing. This vertical drilled bleed will be blocked.




    ... more to come...
    Last edited by Walking-Tall; 10-31-2017 at 06:42 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

  3. #3

    Default

    I am always amazed at the amount of detail guys who know carbs deeply can go into.

    My dad is a whiz with the old GM "quadrajunk" and thermoquad mechanical secondary carbs. I had a few Holley carbs in my teens that I went through hell trying to make work right. Was my own fault - I horribly oversized my intake on a street driven 351W that was my daily driver. Single plane 360 degree offy on a daily - terrible idea really. It made huge power at 6000 but was not great before 3000.

  4. #4

    Default

    Attention to detail is a big one for carburetor tuning.

    Those are a bit more complicated with their execution, but do work with all the same principles and physics. Yes, even with a perceived too-big carburetor on something, dialing in WOT really is the easy part, in comparison to the finesse required to getting the low speed and part throttle air:fuel mixture as efficient as possible for varying vehicle combinations, with idle feed restriction and idle air bleed adjustments. The crisp low speed manners, brisk part throttle acceleration, and the fuel efficiency that can be achieved with something that has had it's idle/transition circuits optimized is really very rewarding.
    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

  5. #5

    Default

    For reference and a look at the original, traditional (clockwise = lean, counterclockwise = rich, idle mixture screws) circuits within Holley modular 2/3/4 barrel carburetors since approximately 1957, that work with fully and solidly established (roughly 100 years ago) efficient and powerful internal combustion physics, where air:fuel ratios should be load-dependent and consistently exactly what they need to be, as well as the WOT air:fuel ratio going to and remaining consistently at what the engine wants/needs throughout the rpm range bottom to top:

    Last edited by Walking-Tall; 10-24-2017 at 10:48 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

  6. #6

    Default

    The carburetor in the first post is going to work today, onto a Victor Jr. 5.3L LS swap monster '77 Blazer. We'll see how she works
    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

  7. #7

    Default

    The Internet needs more great information like this! Thank you for the excellent documentation.

    Love that you built the Ford carb for the LS swap instead of the 6619 "Chevy" carb.

  8. #8

    Default

    Absolutely welcome, and the same to you my friend! If it weren't for your online contribution, I wouldn't have had a clue about HEI module and Duraspark II ignition, which I am thoroughly pleased with it's function every day, day in and day out for years now, being unwaveringly rock solid reliable.

    I guess it's my humble slap back to all the Fords that have been desecrated with Chevy swap nonsense over the years. Here's what's important: it WORKS fantastically... better than it's post-2000 fuel injection could ever hope to.
    Last edited by Walking-Tall; 10-28-2017 at 02:35 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

  9. #9

    Default

    ... and now, an outline to why today, even with large cash outlay (a 2010 receipt for $440.00 to their door was enclosed, for a factory refurbished carburetor), nothing can be assumed...

    I recently acquired the following for $120.00 to my door, a common LIST-1850 600cfm vacuum secondary carburetor...



    Firstly, it's got a primary metering block on it originally designed for 1-11/16" throttle bores... you can read the 4412 stamping in the picture below... the same as I have on my Mustang with it's LIST-4412 500cfm 2-barrel:



    ... which has kill bleeds for down leg boosters (which this carburetor does not have), as well as 0.036" idle feed restrictions suitable for (radically cammed engine) 1-11/16" throttle bores, and 0.0625" power valve channel restrictions... accounted for in their retarded brains with too small # 58 primary main jets...



    This is all wrong... and to add insult to injury... somebody apparently forgot to install some primary idle air bleeds (the outers)...



    ... and the icing on the cake is the following, typical 600cfm 1-9/16" main body throttle bores...



    ... mixed with a throttle base with smaller 1-1/2" throttle bores...



    This was purportedly bought and never used, and after opening it up, the evidence is that that's true... and that's probably a good thing, because this combination likely would not have worked well at all...

    The message... you want something done right, do it yourself. What I end up with is some good refurbished/re-plated parts to put something useful together later... which I will, with appropriate size primary idle air bleeds in place, the right base plate, an appropriate primary metering block with appropriate size primary idle feed restrictions, no kill bleeds, and appropriate size primary main jets and power valve channel restrictions.

    ... then it will be fine...
    Last edited by Walking-Tall; 11-04-2017 at 11:29 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

  10. #10

    Default

    Always amazed at the stupid stuff others think will work!

  11. #11

    Default

    You'n'me both.

    Tomorrow, I'm grabbing three "builder" Holley carburetors inexpensively... an early LIST-3310-1 780cfm vacuum secondary with down leg boosters and front and rear metering blocks and the chromie dual feed fuel line on it, and two LIST-1850 600cfm vacuum secondary's. One of those LIST-1850 600cfm vacuum secondary carburetors will donate it's throttle base to the LIST-1850 in my last post.

    (I'm also going to have a look at a "big valve", built-by-a-race-shop-in-the-80's, 302 with Weiand 4-bbl intake, etc., potentially for my '86 'vert.)
    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

  12. #12

    Default

    With the wealth of data here, it's likely very possible to get a Holley dialed in and working properly.

    On my Four Eyed Saleen I'm going to go with an Edelbrock 600, many to pay tribute to the AFB I had on my galaxie when I was a teenager. That thing moaned like it was going to suck the hood in any second. You could actually hear it way easier than the dual exhaust exiting the burned out (literally) cherrybombs I had on it. Hopefully the Saleen will be equally obnoxious with a small lid to make it an open element but will quiet up some with a proper cal-customs lid on it.

    I thought about running a spread bore Quadrajunk or a thermoquad because my dad is absolutely wicked with them but he does well with the AFB style carbs too.

    One thing I learned a long time ago, Holley and him have not ever played well together. I got much closer to driveable on my 650DP on my Galaxie by myself than I ever did with his well intentioned help. Still I was happy the day the Carter went on and it just ran right.

  13. #13

    Default

    Thanks for the info, I picked up a 4776 recently needing a baseplate. I didn’t even think to check the numbers on the metering blocks.
    84 LX Vert. 5.0 5speed canyon red on white
    99 cobra, electric green on medium parchment, vortech s-trim

  14. #14

    Default

    Quote Originally Posted by erratic50 View Post
    With the wealth of data here, it's likely very possible to get a Holley dialed in and working properly.

    On my Four Eyed Saleen I'm going to go with an Edelbrock 600, many to pay tribute to the AFB I had on my galaxie when I was a teenager. That thing moaned like it was going to suck the hood in any second. You could actually hear it way easier than the dual exhaust exiting the burned out (literally) cherrybombs I had on it. Hopefully the Saleen will be equally obnoxious with a small lid to make it an open element but will quiet up some with a proper cal-customs lid on it.

    I thought about running a spread bore Quadrajunk or a thermoquad because my dad is absolutely wicked with them but he does well with the AFB style carbs too.

    One thing I learned a long time ago, Holley and him have not ever played well together. I got much closer to driveable on my 650DP on my Galaxie by myself than I ever did with his well intentioned help. Still I was happy the day the Carter went on and it just ran right.
    Quite

    Make it a 1406 if you want electric choke, but lean (anti-pun intended, lol) toward the 1405's bit richer calibration, but ultimately, give the engine what it wants/needs.
    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

  15. #15

    Default

    A 1406-2149 600 CFM is what I found. It is reportedly untouched low miles used and recently off a motor that ran great. It looks brand new in the pictures. In theory, it might end up being a slap it on and go deal for $165. We shall see.

    Paired with an airgap it should let that 90 E7 head 302 it's going on spin plenty high. I haven't decided if I'm going to throw on my Edelbrock heads and slide in my comp cam or leave it stock and adding 1.7:1 roller rockers, stronger pushrods, better springs and retainers, etc.

    Near stock but tweaked to scream is likely what it will be. I am not going to put big money into a motor when stock was great and I do not intend to keep that car long term once it's built. Just long enough to finish a full redo on my 86GT.

  16. #16

    Default

    Quote Originally Posted by Lowetlx View Post
    Thanks for the info, I picked up a 4776 recently needing a baseplate. I didnt even think to check the numbers on the metering blocks.
    Very welcome. 600 double pumper, cool. All the same bore/venturi sizes as the 600 above. A similar recipe to the chart above would be a good start for it, minus the larger secondary IFRs (idle feed restrictions) since you've got a secondary accelerator pump shot that easily covers up any potential secondary transition leanness.

    Now, don't carve the metering block information above into stone. It's not common for the metering blocks to have the number stamped on them that matches the carburetor list number that they're supposed to be on or should be on or did come on. The numbers "5924", "5925" & "4412", as seen on the block just above, just happen to be what's installed onto many LIST-4412 500cfm 2-barrels, fairly common, and additionally immediately recognizable to me because that's what is on my car, and others I have seen. Your carburetor's blocks may or may not have "4776" on them.

    This 4777 that I rebuilt, does have "4777" on it's blocks. Most all square bore Holley double pumpers I've done, where I didn't have to add or change blocks for a build, did have matching number blocks:


    Regardless of any of this, most important is that the block/s on a Holley carburetor need to (should) have appropriate sized IFRs for the throttle bore size (as well as by how much more than "stock" camshaft duration the engine has) and appropriate sized PVCRs (power valve channel restrictions, usually only suggested for primary duty) to augment the fueling from the main jets for the venturi size for wide open throttle and maximum power. For instance, the internal orifice sizes and jets in both a 4412 2-barrel block and the primary block of a 3310 4-barrel are identical, due to identical bore/venturi size.
    Last edited by Walking-Tall; 11-01-2017 at 01:29 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

  17. #17

    Lightbulb

    Quote Originally Posted by erratic50 View Post
    A 1406-2149 600 CFM is what I found. It is reportedly untouched low miles used and recently off a motor that ran great. It looks brand new in the pictures. In theory, it might end up being a slap it on and go deal for $165. We shall see.

    Paired with an airgap it should let that 90 E7 head 302 it's going on spin plenty high. I haven't decided if I'm going to throw on my Edelbrock heads and slide in my comp cam or leave it stock and adding 1.7:1 roller rockers, stronger pushrods, better springs and retainers, etc.

    Near stock but tweaked to scream is likely what it will be. I am not going to put big money into a motor when stock was great and I do not intend to keep that car long term once it's built. Just long enough to finish a full redo on my 86GT.
    Cool. I recently did a 1406, and can tell you that the rebuild kit for them from AllState Carburetor (Stock# RK1400) is a good one, that you US folks get for less than 40 bucks, with ethanol-resistant (and steel shaft) accelerator pump plunger, upper seal, and a nice star washer type of retainer for the seal in the upper cover.

    It had a nasty layer of corrosion/residue scale in the bottom of it's float bowls when I opened 'er up...


    but that cleaner and vinegar cleaned up pretty good...




    Like they say, "no news is good news", no issue/complaints, so I assume it's working well.
    Last edited by Walking-Tall; 11-01-2017 at 01:10 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

  18. #18

    Default

    Good to know. They are a very popular carb and I've always seen good things from them. We shall see!

  19. #19

    Default

    So, prior to picking them up, I assumed two of the three builder carbs I picked up were LIST-1850 600 vacuum secondaries. They are a (similar, "reverse-idle" like discussed above) LIST-6619 600 vacuum secondary and an odd bird D5TE (1975, 1-1/2" throttle bores) Ford truck blow-thru design vacuum secondary that has some different and kinda interesting features... maybe more on it later. The 3rd carb is a nice dual feed, dual metering block, drop leg booster 3310-1 780cfm vacuum secondary, the one that made the trip to get them very worthwhile. After rework like with the above throttle base in post #1, the LIST-6619's base will go onto the pretty LIST-1850 that came factory "refurbished" with the wrong size throttle base (in addition to other thrown together wrong components/calibration) as seen in post #9 above.

    The LIST-6619 throttle base's small primary constant idle feeds (a "reverse-idle" feature) at the red arrows are blocked, and new passages drilled for connection with traditional idle mixture screw passages shown by the green arrows:




    Primary (adjustable, 8-32 brass socket set screws, drilled for this at 0.074") idle air bleeds added where there were none, which is most likely how "they" decided to address the primary idle feed restrictions that are too big in the wrong primary metering block that they installed as is:





    The "4412" primary metering block, modified and ready to work RIGHT on/for this carb...

    Before, with 0.036" IFRs and 0.063" PVCRs, and (down leg booster) kill bleeds (small holes at the dog legs):


    After, with (adjustable) 0.027" IFRs and 0.046" PVCRs, and epoxy-blocked kill bleeds:



    These mods, and reassembled with #66 primary main jets... wherever this ends up, it should work fine... certainly better than it was.

    The similarly modified back to traditional function and assembled silver carb above is on a 5.3L LS with a Victor Jr in a giant tires and lifted '77 Blazer, and a reduction of the SIFRs (secondary idle feed restrictions) from 0.040" to 0.029"... actually, a change-out to a regular #39 secondary metering plate with 0.029" idle feed restrictions and 0.073" main "jet" restrictions, because this particular combination with good strong idle vacuum and the single plane intake manifold it just does not need bigger SIFRs for secondary opening or for contribution at idle through the secondary constant idle feed holes. Lesson learned: the 0.040" SIFRs were contributing too much fuel at idle, with the primary idle mixture screws only at about 1/4 turn out. Now, with the primary idle mixture screws at about 1-1/4 turns out each, it is now idling and running and driving like a champ.
    Last edited by Walking-Tall; 11-05-2017 at 12:25 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

  20. #20

    Default

    This "factory rebuilt" LIST-1850-1 600 vacuum secondary puppy has had incorrect components replaced and incorrect calibration corrected and gone through and everything is fresh, and is NOW ready to rip





    I ripped their silly bar-coded 2010 "Holley Remanufactured" sticker off of the choke horn, lol...
    Last edited by Walking-Tall; 11-04-2017 at 11:33 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

  21. #21
    FEP Senior Member qikgts's Avatar
    Join Date
    Jan 2010
    Location
    Rockledge, FL
    Posts
    849

    Default

    Whats with the clamp/cover on the VS spring/diaphragm chamber? Can you provide some info on it? I've never seen one like that before.
    '85 GT

    The other one... 2005 Lincoln LS 3.9L V8

  22. #22

    Default

    Quote Originally Posted by qikgts View Post
    Whats with the clamp/cover on the VS spring/diaphragm chamber? Can you provide some info on it? I've never seen one like that before.
    That's a manual choke cable anchor bracket. It clamps/anchors a manual choke cable's outer jacket, and the cable's stem extends forward to and clamps into the arm you see straight ahead of it, to pull for choke operation. Here's another view:

    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

  23. #23
    FEP Senior Member qikgts's Avatar
    Join Date
    Jan 2010
    Location
    Rockledge, FL
    Posts
    849

    Default

    Quote Originally Posted by Walking-Tall View Post
    That's a manual choke cable anchor bracket. It clamps/anchors a manual choke cable's outer jacket, and the cable's stem extends forward to and clamps into the arm you see straight ahead of it, to pull for choke operation.
    Simple explanation. Thanks.
    '85 GT

    The other one... 2005 Lincoln LS 3.9L V8

  24. #24

    Default

    I briefly made mention to a LIST-6947, D5TE-9510-EA Holley/Ford vacuum secondary 4-barrel above, that could be the beginnings for a blow-thru application, but now see and realize since disassembling it, that it's got the same design features as other under-carbureted Ford carburetor scenarios of a too small carburetor on large workhorse engines, a 390 truck in this case, and such as the Ford Autolite/Motorcraft 2-barrel carburetors I have seen that came off of a 390 truck engine do... namely, reference to atmospheric pressure to the vacuum side of the power valve at wide open throttle... so that the vacuum generated at wide open throttle with the small carb and big engine does not close the power valve (a very bad (lean) situation). This one isn't "reverse-idle", but it's interesting in it's own ways, and so I'll show in images below how these design features could also be used for a blow-thru super/turbo charged application, if someone wished to do so, inexpensively.




    Tube standing beside the choke shroud would be correctly impact-referenced by boost pressure:


    A passage travels down this extra large rib with this main body casting:


    Exits the underside of the main body:


    Connecting passage in throttle base from above hole to just above primary throttle shaft:


    At wide open throttle, there's a drilled hole through the primary throttle shaft, that then connects with the curved passage in the underside of the throttle base:


    That connects with an extra drilling into the power valve vacuum chamber, referencing, in this case, the power valve to atmospheric pressure at wide open throttle... which could be boost pressure instead:




    Anyway, I'm not bothering with creating a blow-thru carburetor, but a decent naturally aspirated one. The factory base plate has a rather large nasty PCV passage at the rear, that likely wouldn't vacuum seal with a regular base/manifold gasket...


    So, instead of monkeying around with epoxy or whatnot to seal off that rear passage properly when the carburetor is bolted down, the wrong (1-1/2" bores) base that came attached to the gold LIST-1850 above happens to work with this body's 1-1/2" bore sizes.



    Even the official Holley numerical list says this is 600cfm, but looking at others with the same bore/venturi sizes, it's actually an approximate 550cfm. Eether either, all the atmospheric reference is blocked off, and it's going to be conventionally calibrated with a single stage power valve, slightly richer (probably #64s in place of the original "close limit" #612s) primary main jetting to go with that, and slightly smaller (adjustable, customary 600cfm-sized 0.046", as opposed to the 0.051" holes in the metering block) PVCRs (power valve channel restrictions), and (adjustable) 0.026" PIFRs (primary idle feed restrictions) and (adjustable) 0.074" PIABs (primary idle air bleeds)...



    I also didn't like the pitted throttle plates Holley put/left in the base plate, so I changed those out...


    The trickier part would be referencing the vacuum secondary diaphragm to work right under boost pressure... making a double pumper MUCH easier for blow-thru use...
    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

Posting Permissions

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