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Thread: 4A084 Specs

  1. #1
    Administrator Papee's Avatar
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    4A084 Specs

    This is quoted from the 084 experimenters Yahoo group.

    The engines were tested at TEN thousand feet at 107 degrees that they were
    tested at.
    > > These engines were run at full load for one thousand five hundred
    > > hours, and THEN dynoed to insure that they pulled the rated power at
    > > those conditions.
    > > AFTER the dyno test, they were taken apart, and the parts were
    > > measured for wear. If the sample engines did not BOTH make the rated
    > > power, AND pass the wear test, the ENTIRE shipment of engines was sent
    > > back.
    > > It is safe to say that most of the members of this site know this,
    > > but for the one or two absolute "newbies" that we may get in the
    > > future, aviation engines are power rated at sea level, onder standard
    > > temperature, (79 degrees I think), and pressure. This power falls off
    > > as altitude rises. If you reverse extrapolate the power numbers from
    > > the conditions that the engines were tested under, you will see that
    > > the engines should pull between 40 and 45 horsepower at sea level.

    Here is a pdf file of the 4A084A engine manual. You can either click on it a read it or left click and save it to your computer.

    http://miniairboatassoc.com/084/4A084a.pdf
    http://miniairboatassoc.com/084/4A084b.pdf
    http://miniairboatassoc.com/084/4A084c.pdf
    http://miniairboatassoc.com/084/OCR.pdf

    a. General.
    Engine Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 41084-2, -3 and -4
    Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 4 cycle gasoline powered
    Number of cylinders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 4 (horizontally apposed)
    Horse power rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 20 at 3600 r.p.m.
    Fuel pump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Diaphragm 3.0-4.5 psi outlet pressure
    Air cleaner . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Dry models 4A084-2, -3 and -4
    Spark plug . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. Shielded
    Gap . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28-.033 in. (.071-.083 cm)
    Magneto contact
    Gap, Fairbanks Morse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..015-.019 in. (.030-.48 cm)
    Gap, Slick Aircraft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .008-.012 in. (.020-.030 cm)
    Valve tappet clearance cold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..007-.009 in. (.017-.027 cm)
    (Intake and exhaust)
    Governor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Centrifugal
    Oil capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 quarts (4 1/2 gts. with oil filter change)
    Alternator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 volts alternating current (ac)
    Starter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 volts direct current (dc)
    Regulator-Rectifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 28.5 ± .5 volts at 1.5 amps
    Firing order . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..1-4-2-3
    b. Dimensions and Weight Models 4A084, -3 and -4.
    Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 20 in. (50.8 cm)
    Width . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28.50 in. (72.4 cm)
    Height . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 22.10 in. (56.13 cm)
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  2. #2
    KWAZY old Southerner... Duane Scarborough's Avatar
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    Re: 4A084 Specs

    New guy again.

    I've saved the 4A084 pdf for future reference. Thanks.

    You said:

    "the engines should pull between 40 and 45 horsepower at sea level."

    So I learned something. When I saw it listed as a 20 HP engine, I kinda'
    put it on my "not interested" list. You changed that.

    That makes me think that a 4A084 would not only be cheaper than a new
    35HP Briggs, but be much stronger as well. (after a little looking, I see that 35HP Briggs don't come cheap)

    (I told you that I was going to ask dumb questions, so here goes)

    Being as it's an "obsolete" military engine, how difficult / expensive is it to find one, and how difficult / expensive is it to find parts?

    When souped up, how much power can someone get from one for a reasonable cost? On a HP per dollar basis, how do you think it compares to a VW engine?

    BTW, I don't have any problem with using an automotive engine. I don't care about what class my boats ends up in. I just want a fun toy.

    I'm still reading the various posts that I find about the 4A084, and still learning.

    Thanks,
    A KWAZY old Southerner... and darn PROUD of it.

    Airboat Pros MiniPro 116 / Frog Spit
    SS rigging - with side by side seating
    Teledyne 4A084-4 engine
    Solex H30/31 Carb
    Arrow Prop 1.73:1 reduction
    67" Whirlwind 2 blade Mini Prop

    under construction

  3. #3
    MAA Vendor

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    Re: 4A084 Specs

    Hey duane, read these, ( Papee's 084 ) and ( Bill's Mini ) and ( Ron and Robins 084 ). We have some of these in stock, 2 new ones and 3 used ones.
    Thanks, Chuck

  4. #4
    KWAZY old Southerner... Duane Scarborough's Avatar
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    Re: 4A084 Specs

    Thanks Chuck,

    I'll do that, and be back.
    A KWAZY old Southerner... and darn PROUD of it.

    Airboat Pros MiniPro 116 / Frog Spit
    SS rigging - with side by side seating
    Teledyne 4A084-4 engine
    Solex H30/31 Carb
    Arrow Prop 1.73:1 reduction
    67" Whirlwind 2 blade Mini Prop

    under construction

  5. #5

  6. #6
    KWAZY old Southerner... Duane Scarborough's Avatar
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    Re: 4A084 Specs

    Thanks everyone.

    I "may" have just screwed up, and if so, it's all you guy's fault.

    I found a 4A084, new in the crate on Ebay, and placed a bid on it.

    If this turns out bad, I'll blame it all on you guys.

    BTW, he has 2 more, if anyone is interested.
    A KWAZY old Southerner... and darn PROUD of it.

    Airboat Pros MiniPro 116 / Frog Spit
    SS rigging - with side by side seating
    Teledyne 4A084-4 engine
    Solex H30/31 Carb
    Arrow Prop 1.73:1 reduction
    67" Whirlwind 2 blade Mini Prop

    under construction

  7. #7

    Re: 4A084 Specs

    Hey Duane where are you located Chuck has 2 new ones at the shop we also have 2 new belt drives for them that we can do a good deal even the o84 engines on call him up 353-330-1015

  8. #8
    KWAZY old Southerner... Duane Scarborough's Avatar
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    Re: 4A084 Specs

    Thanks David,

    I'm in Wilson, NC. About 40 miles East of Raliegh.

    I guess that I jumped the gun a bit by bidding on ebay for the motor, but I just couldn't help myself. Shame on me. I bid what I thought that it was worth to me. Damn. I'll probably get it anyway.

    If I "win", I am pretty sure that I will be looking for a belt reduction drive, etc. etc.....

    I have created a monster.
    A KWAZY old Southerner... and darn PROUD of it.

    Airboat Pros MiniPro 116 / Frog Spit
    SS rigging - with side by side seating
    Teledyne 4A084-4 engine
    Solex H30/31 Carb
    Arrow Prop 1.73:1 reduction
    67" Whirlwind 2 blade Mini Prop

    under construction

  9. #9

    Re: 4A084 Specs

    Does anyone know what the valve adjustment is for the 084? I have looked thru that @#%!&^%(*&^%$$ TM until i'm mad. That brings back some old memories of working on military equipment. And i don't miss it.

    Thanks

  10. #10
    Administrator Papee's Avatar
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    Re: 4A084 Specs

    I know it's there LOL, I had a hard time finding it also and just saved the page with that stuff on but now I can't find it. Great now I'm looking for two things. I'll never get ahead
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  11. #11
    Senior Geezer buster's Avatar
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    Re: 4A084 Specs

    Airhead and Papee,

    I think you will find that the 084 lifters are hydralic, and require no adjustment. Correct me if you find out that I am wrong.

    Dave
    IF YOU WON'T STAND BEHIND OUR TROOPS, THEN JUST STAND IN FRONT OF THEM!

  12. #12
    KWAZY old Southerner... Duane Scarborough's Avatar
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    Re: 4A084 Specs

    Buster, Airhead, and Papee,

    I've done some searching myself, with very few results. The best I've come up with is that they are hydraulic, like Buster said. Even so, it seems like there'd be some target clearance when the lifters aren't pumped up.

    I'll keep my ears open for more info....

    Thanks,

    Duane
    A KWAZY old Southerner... and darn PROUD of it.

    Airboat Pros MiniPro 116 / Frog Spit
    SS rigging - with side by side seating
    Teledyne 4A084-4 engine
    Solex H30/31 Carb
    Arrow Prop 1.73:1 reduction
    67" Whirlwind 2 blade Mini Prop

    under construction

  13. #13
    Senior Geezer buster's Avatar
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    Re: 4A084 Specs

    Duane,

    If you pull off one of your valve covers, you will not find any adjustment screws. That is how I determined that they must have hydraulic lifters.

    Maybe your engine is different than mine, but I don't think so.

    Dave
    IF YOU WON'T STAND BEHIND OUR TROOPS, THEN JUST STAND IN FRONT OF THEM!

  14. #14
    KWAZY old Southerner... Duane Scarborough's Avatar
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    Re: 4A084 Specs

    Buster,

    I don't have any oil leaks YET, and ain't going to try starting one.

    As it turns out, as I was about to reply to YOUR post, I got this reply from Les Smoot.

    Duane,

    Hey there! I am in China for a bout 3 more weeks, I have
    been in and out of several hotels ...internet is spotty!

    You are spot on!

    NO valve adjustment ...hydraulic lifters. If you are getting
    valve noise it's because of a worn lobe on the camshaft or
    the lifter itself is NOT puming up. This problem starts to
    pop up when an engine has been rebuilt many times over
    and the same lifters and camshaft are re-used vice replaced.

    If the engine noise is only there when cold but clears up as the
    engine gets to temp it's likely a bad lifter .......

    Hope to be home by mid September ..........

    Cheers,
    Les


    BTW, Buster, I never said you was wrong. I was just trying to get the answer from someone who's been into these engines many, many times.

    Thanks,

    Duane
    A KWAZY old Southerner... and darn PROUD of it.

    Airboat Pros MiniPro 116 / Frog Spit
    SS rigging - with side by side seating
    Teledyne 4A084-4 engine
    Solex H30/31 Carb
    Arrow Prop 1.73:1 reduction
    67" Whirlwind 2 blade Mini Prop

    under construction

  15. #15
    KWAZY old Southerner... Duane Scarborough's Avatar
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    Re: 4A084 Specs

    Airhead,

    See above.

    Thanks,

    Duane
    A KWAZY old Southerner... and darn PROUD of it.

    Airboat Pros MiniPro 116 / Frog Spit
    SS rigging - with side by side seating
    Teledyne 4A084-4 engine
    Solex H30/31 Carb
    Arrow Prop 1.73:1 reduction
    67" Whirlwind 2 blade Mini Prop

    under construction

  16. #16

    Re: 4A084 Specs

    Duane,

    I checked the lifters from a parts engine i bought and they are definately hydraulic NO ADJUSTMENT REQUIRED This makes sense because of what they were used for

  17. #17
    Administrator Papee's Avatar
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    Re: 4A084 Specs

    Sorry guys I read right past that one. I knew this because I have already replaced a head on mine. I thought he was asking for torque specs.
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  18. #18

    Re: 4A084 Specs

    Anyone know what the timing is for the 084? The TM says line up the marks Now, i cant do that I thought i had found 19* BTDC in the TM, but i don't know for sure. And 19* sounds like really too much.

    Thanks

  19. #19

    Re: 4A084 Specs

    I looked through the TM again and still cannot find the timing. I looked at the original flywheel and the timing mark says TDC. So i must assume that is the timing. Just want to clear up the 19* business, i don't know where i got that unless i was thinking about point gap.

    If anyone has something different, please post.


    Jim

  20. #20
    KWAZY old Southerner... Duane Scarborough's Avatar
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    Re: 4A084 Specs

    Airhead,

    There is a how-too on the Yahoo Experimentor's group.

    Here's a link to it.

    http://groups.yahoo.com/group/A084Exper ... the%20084/

    Let me know if you can't access it, and I'll get it to you some other way.

    Duane
    A KWAZY old Southerner... and darn PROUD of it.

    Airboat Pros MiniPro 116 / Frog Spit
    SS rigging - with side by side seating
    Teledyne 4A084-4 engine
    Solex H30/31 Carb
    Arrow Prop 1.73:1 reduction
    67" Whirlwind 2 blade Mini Prop

    under construction

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