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  1. #1
    FEP Senior Member 84specialed's Avatar
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    Default fuel mileage? 200 6?

    Im buying a NICE 81 fairmont futura for $300. It has a 200 straight 6? And a c4 auto trans? Not really sure what size engine or what trans. It is a straight 6 auto.lol. it runs well and has about 80k on it. Was wondering what kind of fuel mileage to expect? My 82 gt is gonna be down for a while and im hoping it does better than my current dd, which is a 70 f100 with 240 6 and 3 speed on the column. Im currently getting around 15-20 with the truck.

  2. #2

    Cool

    thats pretty much the mileage of the futura

  3. #3
    FEP Senior Member 84specialed's Avatar
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    Quote Originally Posted by darko View Post
    thats pretty much the mileage of the futura
    Oh well, at least it has an fm radio! Is it a 200? What kinda trans? I was thinking of swapping my old srod 4 speed out of the 82 into it, as i have a few pedal assemblies. Will the trans work? Came out of a stock 82 mustang gt.

  4. #4
    FEP Super Member xctasy's Avatar
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    Economy on any Fox I6 was great while ambeled along, but poor when used hard, basically due to the wide ratio gearbox. Using an 82 SROD from the 2-BBL GT means the ratio spread is wider, as all SROD 3.3's ran a 3.08:1 diff and 0.81 top. The V8 SROD has a 0.70:1 top and taller first and second gear ratios.

    Stock LA Basin 7 mile CAFE millage numbers weren't released for the 4 speed Fairmont, as the option of SROD was withdrawn, but the Mustang/Capri 4speed it was rated at 20 mpg City and 30 Highway, with 23 mpg composite, and the EPA Revised were 18, 28 and 22 respectively. In practice, it could be great or lousy just based on driving style. 16 to 17 is common when not concentrationg on good mileage, but 21-22 is easily within reach in split city and highway conditions

    http://www.aboutautomobile.com/Fuel/1981/Ford/Mustang

    Compared to the stock 2.73:1 ratio Fairmont auto, http://www.aboutautomobile.com/Fuel/1981/Ford/Fairmont

    you could pick up 11 to 25% better fuel figures with a 3.08/srod than the C3 or C4 BV code Fairmonts. BM code Mustangs were around in reasonable numbers, but were only high mount Blue engines.

    http://www.coverbrowser.com/image/motor-trend/326-9.jpg





    http://www.ascmclarencoupe.com/Liter...arch1981_1.jpg
    http://www.ascmclarencoupe.com/Liter...arch1981_2.jpg


    The IJ204 Blue engine with high mount starter has a block like this



    It needs a specific Fox bellhousing to fit the SROD V8 gearbox, as the clutch operation changed from the earlier Toploader 3.03 and earlier 2.77 gearboxes. The diff may be a 6.75" Stirling, which leaves you with 3.08 or 2.73 gearing.


    If its low mount Gray CJ232, it requires a redrilled V8 SROD bellhousing, with the top two bolt holes shifted downwards.

    1981-1983 Fox bodies were technically the only cars with big bell 200's. They had the football cat exhast with 4.5" outlet.



    Check for the CJ232AB front rocker decal, should be gray colored rockerand block.



    For this reason, a manual transmission option can be ultra expensive...You can neutral balance any 164 teeth truck Toploader, T5 or M5OD or ZF flywheel, and redrill the centre bolts by slotting them inwards. Or you have to order a blank undrilled 164 teeth neutral balance SGI rated flywheel racers use, and drill it to the 2.75" pitch of the six bolts. The SBF uses a 3.0" pitch set for the six bolt. Then the top two trans bolts have to be slotted and lowered.

    The redrilling is easy. See http://www.classicinlines.com/V8Bell.asp



    The high mount 4 speed factory options are numerous but the best two are the D9BC-6392-CA and E1ZR-6394-AA bellhousings, which were normal options on the 3.3 Mustangs. The first of the 3.03 bell housings, the common C7ZA-6394-A can be made to work, but the cable clutch quadrant means the engineering has to be specificly changed for that one to work well. See http://straightsixshootin.weebly.com/cable-bell.html

  5. #5
    FEP Senior Member 84specialed's Avatar
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    Thanks xctasy!

  6. #6
    FEP Power Member jessew's Avatar
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    I get about 12 in town, 15-18 highway.
    1983 Mercury Zephyr Z7 AM Radio, no a/c, 200 3.3l I6, C5 Automatic, Police scanner, 40 Channel Cobra 29LTD CB radio, PA system mounted under bumper

    2008 Ford F150 XL 2wd v6, 5 speed.

  7. #7
    FEP Super Member xctasy's Avatar
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    Compared to a lock-up clutch c5, a wide ratio SROD or T5 is worth a significant fuel economy saving, at worst, 10%, at best, 25% on the highway. Most cases, Fords I6 autos were overgeared, so a manual with overdriven top often helps restore performance via a more performance orientated diff. 9 times out of ten, Ford would give the manual a 13% higher numerical diff of 3.2:1 verses 2.83 on old Mustangs, and 3.08 verses 2.73 on the newer Foxes.


    Mines been messed with, has a 100 cfm peak flow 170 1963 Falcon cylinder head, but it still gets 12 us mpg around the steepest hills in my town, and 17 us mpg tops on the open highway. Auto, 1981 3.3, 2.73, 3100 pounds with 200 pounds of tools, long range spare fuel, and all its bits and bobs.

    The manual gearbox with 3.08:1 and over driven top gives a 2.49:1 final drive. A stock 3.3 auto had a 2.73:1 diff. With an SROD V8 0.7:1 top has a 1.91:1 top gear, or 43% overdrive.

    Tets by Colt in 1979 showed that for every 30% less gearing with an 0.77:1 overdriven top, you can get a 9% reduction in fuel consumption. Despite what Gearvendors et al might say, a 30% drop in revs in top gear never gives a 30% drop in fuel economy, because road load due the engine rpm only 1/5th of the total load at 60 mph, (transmission, rolling resistance, air drag,differential are still constantly taxing power at any speed)

    A check on automatics verses manuals give a 5% reduction in fuel consumption every time you run a manual verses an automatic, if the gearing is the same and the fuel consumption cycle is driven in the same gear ratios.

  8. #8
    FEP Power Member craigerSS's Avatar
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    I once had a 79 zephyr with that engine combo,don't remember the gas mileage but I do remember my top speed of 80mph and a long time to get there
    here's to the freakin' weekend,I'll drink to that

  9. #9

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    Quote Originally Posted by 84specialed View Post
    Im buying a NICE 81 fairmont futura for $300. It has a 200 straight 6? And a c4 auto trans? Not really sure what size engine or what trans. It is a straight 6 auto.lol. it runs well and has about 80k on it. Was wondering what kind of fuel mileage to expect? My 82 gt is gonna be down for a while and im hoping it does better than my current dd, which is a 70 f100 with 240 6 and 3 speed on the column. Im currently getting around 15-20 with the truck.


    On my i6 with a c4 transmission it costs $41.00 to travel 200km. My 88 GT with a 302 HO would travel 300km on $51.00, and was way, way faster. Actually I sold the GT to get the i6 because of all the good things I read and heard about it. However, it is utterly gutless as well as horrible on fuel so I am looking into a V8 build because of this, unless I can find a rebuild kit that isn't overly too expensive.

    After reading that Motor Trend review on the 3.3L, when this engine is functioning properly it seems quite decent on fuel. Driving a constant 55 mph they got 30mpg and drove 375 miles??? WOW that's more like it.


    Right now my car is parked in my driveway because I sprung an oil leak from somewhere around the oil pressure sending unit and it lost lots of oil.... Sigh.
    Last edited by AC Trust; 11-08-2012 at 09:48 PM.

  10. #10
    FEP Super Member xctasy's Avatar
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    Since your not governed by emissions regulations, you can fix the performance and economy issues easily.

    Ford Dearborn made no major changes to air flow and carburation, compression or cam timing on the 3.3, and its those four things that make it loose big time on power verses economy stakes.

    Get the head planed 120 thou (3.05 mm) to elevate the compression ratio to 11;1, and apply the double roller timing chain and have a distributor expert rework the Duraspark II ignition with the following specs. Limit total advance to 32 degrees total with 16 degrees static. Replace the steel head gasket with a composite gasket of about 45 thou thickness, and the head needs a simple amount of porting and a direct mount 5200 Weber 2-bbl, 32/36 Weber or 38 DGEV Weber with a cable kickdown for the C4. A 3.08:1 diff instead of the 2.73 gears won't hurt your millage any.

    You'll get by with 87 octane with that combo.

    That will take you to the same hp as a good Aussie cross flow 3.3 or Argentina SP 221 for power. This will give you about 130 to 140 hp net without much effort. The stock cam was a good one for the year, but you can go up to a 264/110 Clay Smith cam for extra power.

  11. #11

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    I have ducoment gas milage and maintenance logs for my wagon with a 200 six c5 and 2.73 for the first 60,000 miles. It got a best of 28 on a couple occasions and a worst of 13 but I believe that was when it was being used to pull a small pop up trailer on vacation. It seems to have averaged in the 22-23 range in daily driving.

  12. #12
    FEP Super Member IDMooseMan's Avatar
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    Quote Originally Posted by xctasy View Post
    ...Get the head planed 120 thou (3.05 mm) to elevate the compression ratio to 11;1...You'll get by with 87 octane with that combo...
    Really? I was under the impression that anything over 9.0:1 CR required 91 octane minimum.
    Craig "IDMooseMan" Peters
    1979 Mustang Ghia Notchback, 2.3L, Holley 5200, 4-spd, 3.08:1 7.5" diff, A/C, PS, PB, AM/FM/8-Track, Sunroof, Rear Defroster
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  13. #13
    FEP Super Member xctasy's Avatar
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    Default Minimum AKI requirements for High Compression I6's

    Ford could have raised the compresion to from the stock 8.4:1 to over 9.2:1 and still run a 3.3 on 87 octane if the advance curve was optimised to suit. Problem was 1-bbl carb, cam duration due to timing chain, and 49 and 50 state sniffer test requirements. If they ran 1983 EEC4 and TFI like on the HSC 2.3, and a good feedback 2-bbl likie on the HO Escort, they could have probably gone even higher.


    Because you've probably seen Vizards graph on compression ratio verses octane (Modifying your SOHC Ford), you'll know that each time you step up the exhast closing duration, you can raise compression ratio. Big cams can take quite large compression ratios because the exhast closing event is dealyed. Effective compression ratio is changed when a non stock timing chain set is employed. According to the NHRA site on head castings and cams, the stock 256 cam used by Ford in that year had changes to its built in cam timing. That's a few degrees different for a start, worth a standard to regular grade difference in gasoline requirement if you take measures to avoid knock.

    Info I have from the Falcon Six Handbook and some back ground work from a Collardo member was that the 1982 cam and the yellow groment Duraspark II module, which are not legal emissions swaps for states with IM testing, allow you to raise compression considerably on stock.

    The main issue is what happens with peak advance and the timing off idle. The rest is setting the effective compression ratio back enough to avoid knock. Ford pushed the envelope to a whole new level in Australia in the 80's and 90's on unleaded alloy head sixes when they adopted US pump grade fuel, and found 8.6 to 8.8:1 with alloy head and 256 carb and 268 degree EFI degree cams could take as little as 87 AKI with about 34 peak duration, and 9 static at idle. Similar in the US with the 1986 5.0 EFI and HSC2.3 and 2.5's, they pushed the compression verses octane friendship for iron heads via Thin Film Ignition. They had service problems with fitting bigger lift cams on 86 Mustang 5.0's, but could hack the 87 AKI (RON+MON/2) fuel.

    The problem with US emisions spec engines is that raised compression hurts NOx, in some cases causing stock idle and load emissions to fail the IM test, and, on a single 1-bbl iron headed engine, create hurtful detonation with the stock settings.

    Depending on your states sniffer requirements, Cam timing changes are technically forbidden for 50 state compliance unlesss you can prove mantenaince or reduction on stand tune emissions.

    When you advance or retard the cam from stock to get cold cranking compression down enough, you can then optimise standard compression ratio upwards a whole heap, but avoiding knock. If your in a cold climate with lots of short running, a raised compression ratio makes a huge improvement.

    My car is busy getting mods to run 12.7:1 with a planed down 1963 head and water injection. I'm experiementing with how little octane you need with each compression step for emissions engines via a 1987 EFI Cross Flow 4.1 liter I6 piezo electric knock sensor on the front head stud on my 81, as it was a TFI I6 with EEC4 control just like the Tempo/Topaz/Taurus HSC.
    Last edited by xctasy; 11-13-2012 at 12:43 PM. Reason: US Pump ratings are AKI (RON+MON/2) not RON

  14. #14
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    xctasy knows his I6 stuff.

    The 1980 Mustang Ghia hatch I had with 200/C4/2.73 rear/P215/60-14 tires got very close to 30mpg and that was using every trick in the book to maximize economy.
    85 Mustang Coupe, 3.3L I6, C4, 8.8 3L23, 17x8 wheels. About 70% towards firing it up.

  15. #15
    FEP Member 80 Capri's Avatar
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    My 80 200/SROD, with all the emissions crap removed, single out header, MSD 6A ignition box, Taurus electric fan, 1 wire 90 amp alt, and a 215 cfm carter YF carb gets 24 city, and 28-30 hwy at 65 mph. I drive it like a granny. There's more in it, my timing curve is nowhere near optimized.
    Last edited by 80 Capri; 11-23-2012 at 01:05 PM.
    1980 Capri RS

  16. #16

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    Very interesting info guys!

    I am tossing back and fourth about weather or not I should rebuild my I6 and T5 it or to start a V8 build and T5 it. There is something so interesting about the I6 though, it is tough for me to make a choice. Not many I6's around in my city or country for that matter lol.

    I am currently looking into the costs of a V8 build VS I6 rebuild. Fuel economy means a lot to me though so the homework continues... I like what I am reading here in this thread. 130-140 hp would be nice, mild but nice


    I fixed my oil leak for $17.00 and she's been fine ever since!
    Last edited by AC Trust; 12-02-2012 at 08:01 PM.

  17. #17

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    My first car was an '81 Mustang with the I6. I remember the fuel mileage wasn't that great. I would get mid to upper teens with it. It was a gutless motor but it treated me great. It was one of the smoothest running motors I've ever had.

    I remember blowing the radiator and driving that thing home 30 minutes overheating badly with no coolant. The engine was knocking like a box of rocks. Fixed the radiator and it still ran perfect.

    I did like that motor but if I had the choice I would go with a V8
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  18. #18

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    Quote Originally Posted by gregpro50 View Post
    My first car was an '81 Mustang with the I6. I remember the fuel mileage wasn't that great. I would get mid to upper teens with it. It was a gutless motor but it treated me great. It was one of the smoothest running motors I've ever had.

    I remember blowing the radiator and driving that thing home 30 minutes overheating badly with no coolant. The engine was knocking like a box of rocks. Fixed the radiator and it still ran perfect.

    I did like that motor but if I had the choice I would go with a V8

    I guess that is the trade off, iffy economy, slow as a snail but stone reliable lol!

  19. #19

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    My next car was an '86 GT with the fuel injected 5.0. It got substantially better mileage than the old I6 did though. I also believe the newer roller 5.0 motors to be just as reliable.

    I'm not sure how the mileage would be with a T5 behind an I6. Mine was an auto so it had no overdrive gear. The GT I later bought had a T5. I would get low 20's with that car.
    '79 Indy pace car T-top
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    '81 Cobra T-top
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  20. #20
    FEP Super Member xctasy's Avatar
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    Quote Originally Posted by gregpro50 View Post
    My first car was an '81 Mustang with the I6. I remember the fuel mileage wasn't that great. I would get mid to upper teens with it. It was a gutless motor but it treated me great. It was one of the smoothest running motors I've ever had.

    I remember blowing the radiator and driving that thing home 30 minutes overheating badly with no coolant. The engine was knocking like a box of rocks. Fixed the radiator and it still ran perfect.

    I did like that motor but if I had the choice I would go with a V8

    The 81 I6 in mine now has a 1963 head on it, and I've downgraded the radiator size because New Zealand isn't Arizona, Texas or Collarado. The car has been absolutley hammered while clearing out 40 years of rusty head sludge since the donar 170 head was on the 1966 200 cube engine I found in on as a freebie offering from a workmate in 2003.

    It's a tough engine, tougher than any thinwall 302 because there is no intake manifold gasket, acess to the carb, exhast and plugs are the best ever, but sooo gutless. I've made this comparison here many times, but our same year Antiopdean Aussie 3.3 and 4.1 cross flows were about as powerfull as your early pre 85 4.2 and 5.0's, 121 to up to 149 to 164 hp for the 4.1 EFI's. Mileage in the heavier Falcon, Fairmont, Fairlanes and LTD's was highway US 27 on the 5-speed 3.3, and 22 mpg on the 3-stage auto EFI 4.1. Stock Fox 3.3's never got more than 92 hp, and sometimes 85 hp, so the head swap with the stock 256 degree Ford cam used on both the American and Australian continent was worth 29 to 39 hp.

    Your Foxes never got the 250 log head, but if you did it wouldn't have gotten more than 99 hp, and with a better head and EFI with the same 256 degree cam, the engine yielded 40 extra horsepower. With a cam change, 65 extra hp.

    So the basic block and under head stuff is well able to take a 42 to 66% power boost with no cam greater than the 4.9 F150 i-6 emission cam. Ford chose not to do any extra work on the induction and head...the 81 onwards exhast, ignition, cam and basic engine was as good as the 18 years of 3.3/200 cube development could make it.

    The technology was there in 1981 to do so, and Edsel Ford II was looking at doing a deal with Honda on an American version of the Aussie Cross Flow 3.3 and 4.1 engines. Instead, the gutsier but still lethargic 3.8 V6 came on stream, and everyone knows that any 4.2 or 5.0 Fox was a very decent quarter horse verses mpg performer compared to the 3.3

  21. #21

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    Quote Originally Posted by xctasy View Post
    The 81 I6 in mine now has a 1963 head on it, and I've downgraded the radiator size because New Zealand isn't Arizona, Texas or Collarado. The car has been absolutley hammered while clearing out 40 years of rusty head sludge since the donar 170 head was on the 1966 200 cube engine I found in on as a freebie offering from a workmate in 2003.

    It's a tough engine, tougher than any thinwall 302 because there is no intake manifold gasket, acess to the carb, exhast and plugs are the best ever, but sooo gutless. I've made this comparison here many times, but our same year Antiopdean Aussie 3.3 and 4.1 cross flows were about as powerfull as your early pre 85 4.2 and 5.0's, 121 to up to 149 to 164 hp for the 4.1 EFI's. Mileage in the heavier Falcon, Fairmont, Fairlanes and LTD's was highway US 27 on the 5-speed 3.3, and 22 mpg on the 3-stage auto EFI 4.1. Stock Fox 3.3's never got more than 92 hp, and sometimes 85 hp, so the head swap with the stock 256 degree Ford cam used on both the American and Australian continent was worth 29 to 39 hp.

    Your Foxes never got the 250 log head, but if you did it wouldn't have gotten more than 99 hp, and with a better head and EFI with the same 256 degree cam, the engine yielded 40 extra horsepower. With a cam change, 65 extra hp.

    So the basic block and under head stuff is well able to take a 42 to 66% power boost with no cam greater than the 4.9 F150 i-6 emission cam. Ford chose not to do any extra work on the induction and head...the 81 onwards exhast, ignition, cam and basic engine was as good as the 18 years of 3.3/200 cube development could make it.

    The technology was there in 1981 to do so, and Edsel Ford II was looking at doing a deal with Honda on an American version of the Aussie Cross Flow 3.3 and 4.1 engines. Instead, the gutsier but still lethargic 3.8 V6 came on stream, and everyone knows that any 4.2 or 5.0 Fox was a very decent quarter horse verses mpg performer compared to the 3.3

    Awesome info! I love to read and learn more about the 200ci i6. I use mine everyday to go to work and back in this cold -15 to -20 snowy winter. In the morning when I start it she bursts to life and when I take it in for an oil change and the person says "bring it to 2000 rpm and hold for a few seconds" the roar is so unique and different, everyone in the bay cant help but look and wonder what I have under the hood. Lot more bark then bite tho lol.

    I would like to learn more on this engine for rebuild / performance purposes, what reading material would you all recommend? I believe it's called The Falcon Handbook, is that decent?

    Thanks!

  22. #22
    FEP Super Member xctasy's Avatar
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    The Falcon Handbook is the one to get. It fills in the gaps. But far more signifcant is Horseing around with the Mustang Six, an Ak Millar article made with Fords blessing in 1967 (http://www.classicinlines.com/HA1.asp), and it shows you that with a just a slightly milder cam then the 4.9 F150 truck, you can get a 92% boost in power from 65 rear wheel horsepower typical of all Ford 200's from 1963 to 1983, and boost it to 125 rear wheel horsepower ( about 158 hp on a a manual Fox body, bascially 82 2-BBL Mustang 5.0 GT).

    No loss in low end torque, , no major gain in needed maximum revs, but a huge expanse in possible rev range, just like the best K code 289 Mustangs.

    The Six Cylinder gospel to the Americans is that the Aussies, Argentinians, and the English and Germans got right into making the heads and carb or Injection combinations flow good horsepower numbers without camshaft p-rofiles much bigger than the 268 degree F100/150 240/300 truck cam. And with port of port carb systems like the 1962-63 AC Ace Stage 6 Triple Weber carb system, the 1972 E49 Aussie Chrylser Charger Hemi 265 or DBS Aston Martin Vantage 4 liter Triple Weber or theAussie Duggan and Phil Irving heads, you can make a huge amount of power and torque with very little cam lift and duration.

    And so aiming for a 92% power increase is possible with a Classic Inlines head and a fairly simple EFI system, you can even get to 267 flywheel horspower (211 rwhp) with just a 4-bbl and the best camshaft.

    But matching the 5.0 power figures is possible without making the CHP have a heart attack when the hood is opened.

    See http://www.classicinlines.com/dynoroom.asp

  23. #23
    FEP Senior Member
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    Good info.
    85 Mustang Coupe, 3.3L I6, C4, 8.8 3L23, 17x8 wheels. About 70% towards firing it up.

  24. #24

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    Thank you! Excellent info Xctasy!

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