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  1. #1
    Gregor32's Avatar
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    Tower 75 rpm figures?

    hi, i was thinking about buying a tower 75 but wondered if any one has any prop figures? i want to put it on a prop jet and was hoping it would turn some good rpms on 11" props. does anyone have any readings for 11" props? and has any one used a full length pipe on this engine?
    thanks Greg

  2. #2
    Gregor32's Avatar
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    RE: Tower 75 rpm figures?

    well i received my tower75 a few weeks ago, quite cheap with a $20 off code!, i have nearly finnished the run in.
    im using fuel containing 10%nitro 15%coolpower and 3%castor so a total of 18%oil. i tested three props today.
    master airscrew scimitar 12x6 11900rpm
    apc 11x8 12630 rpm
    bolly 11.5x7 13050
    these figures were peak, i also will try with a full tuned pipe as soon as i fabricate a header to suit.
    reguards greg

  3. #3
    rainedave's Avatar
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    RE: Tower 75 rpm figures?

    Greg, unless you need a header with special geometry Mac's is now selling them for the Tower engines. Part #2890.

    David

  4. #4
    Gregor32's Avatar
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    RE: Tower 75 rpm figures?

    just tried a full length tuned pipe (macs 1190), same fuel as above,
    APC 11x8 13,350
    still playing with the tunning length.
    mid seems fat and theres a jump onto the pipe.
    Greg.

  5. #5

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    RE: Tower 75 rpm figures?

    Apc 13-6 11400 rpm
    APC 12,25-3.75 14400 rpm

    These where steady at peak after only four 250 cc tanks

  6. #6
    Gregor32's Avatar
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    RE: Tower 75 rpm figures?

    still further testing- im now holding a steady 13950 just off peak, it will idle well and snap to wot without hesitation but at mid throttle it loads up and stops in about 5seconds, spitting fuel out the carby, weird! maybe i need a new carb?
    greg.

  7. #7
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    RE: Tower 75 rpm figures?

    Greg,

    I had the same problem with one of my Tower .75s and so did several other people that posted in the engine forum. I know the problem. Screams at the top end, idles perfectly and snaps to WOT, but spits fuel in the mid range and sometimes quits. Tower replaced the carb for me, but in the interim, I used a carb from an SK 90. It is the same throat diameter and ran perfectly.

    Personally, I think that the manufacturer of the Tower engines in China got an incorrectly made batch of low speed needles. Either that or the camming groove that moves the low needle in and out was cut at the incorrect angle.

    The second Tower .75 I bought ran great from the start.
    Ed Moorman, AMA 553, Former R/C Report Fun Aerobatics Columnist. 76 and up to my old tricks!

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    RE: Tower 75 rpm figures?

    I'm having trouble with my tower too, buy the 75AX!!!

  9. #9
    Gregor32's Avatar
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    RE: Tower 75 rpm figures?

    thanks Ed i will contact tower for a replacement carby.
    cheers Greg

  10. #10
    Gregor32's Avatar
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    RE: Tower 75 rpm figures?

    the carby problem is now fixed, no thanks to tower!!! they just said i wasnt tuning properly. any way i now have a just engines TN2 carb with 9.5mm bore and it runs great now. my latest set up is in a 60 size pattern plane with a macs 60 size muffled pipe turning an APC12x8 at 12000 even, i am looking forward to flying this setup. Greg

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    RE: Tower 75 rpm figures?

    My Tower .75 came with two head gaskets installed, .004” and .0085” thick. Does anyone know if two head gaskets from the factory is normal?

    Bill

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    RE: Tower 75 rpm figures?


    ORIGINAL: Gregor32

    hi, i was thinking about buying a tower 75 but wondered if any one has any prop figures? i want to put it on a prop jet and was hoping it would turn some good rpms on 11" props. does anyone have any readings for 11" props? and has any one used a full length pipe on this engine?
    thanks Greg
    I get 14,700 to 14,800 rpm with a 11 x 7 pusher APC prop but cannot set the low end to be reliable. I used a 12 x 6 MA tractor prop for the first tank and the low needle setting seemed reliable. I have ordered a 11 x 8 pusher hoping it will help correct the low speed rich condition. Ground clearance is a problem with 12” props.

    Hope the new prop works without further difficulty.

    Bill

  13. #13

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    RE: Tower 75 rpm figures?

    Bill

    The two headshims are there to adjoust the compression ratio of the engine, the more headshims the lower the compression, and with that, you'll be able to make the engine bahabe better with a specific fuel.... the engine with higher compression will behave better with lower nitro fuels....

    In my case i use Homebrew FAI fuel, and I left only the thin shim.

    I get with a 11x7 Scimitar propeller after 3 tanks arount 14700RPM, with a 12x6 Scimitar I got about the same RPMs, the engine is super, and I don't have the problems with the midrange...I just broke it according to Dar Zeelon's method and the engine ist supperb...sincerly the best Engine I've ever had.

    The only problem that I've had is that the engine ist almost always screaming, with half throttle und almost 1/3 Throttle, so I have problems trying to slow down my plane, I have to bring it to idle...and I get always nervous, so the thing is that I'll need to try a couple of propellers to suit better my engine/plane combination... I have a 12x6 APC which I haven't tested yet, but I think it will behave better (the APC will load more the engine), but maybe it won't be enough...maybe a 12x7 or 12x8 will do the trick...

    I'v bought the engine about one and half year ago, and now I'm living in germany, I haven't worked with the engine for 8 months..and I guess I won't be able to do it to test it...

    Try yours and tell me how it goes,


    Cheers

    Jorge
    Jorge Andres Estrada

  14. #14

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    RE: Tower 75 rpm figures?

    A Graupner 11x8 Pusher prop will turn 13,000/13,100. Reliable idle is about 3500 rpm.

    In tractor configuration a 12 x 6 prop appears to load the engine in a better range than the 11 x 8 pusher.

    Bill

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    RE: Tower 75 rpm figures?

    hi  i know of other problems  with the tower 75 's     -carb was leaking air- not good-  will cook a new  aluminum engine quickthe problem with most  engines sold is they cannot make as good a carb -as OS doescost goes out the window if you buy a new engine-then have to replace the carb to make it run as well as it should-mostly pays to put you dollars into an OS productsthe new  OS AX series seams like the way to go for a strong -trouble free 75-you have an investment to protect-  engine trouble will blow it
    \" The power and performance glo fuel , 15 % Morgan Omega \"

  16. #16

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    RE: Tower 75 rpm figures?

    Even though the "best" engines may fail.the problem with tower carbs is very well known around here, the carb was not fully seated...I had to use quite a bit force to seat it properly, until I've heard a click.Tower engines are very well known around here for being top engines, and with more power than other 75 engines on the market.I've never had problems with it!
    Jorge Andres Estrada

  17. #17
    Iflyglow's Avatar
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    RE: Tower 75 rpm figures?

    I totally agree on the value of the Tower .75. Just make sure the carb is pressed in far enough to seat the o-ring, and you are good to go. Ihave never seen a another .75 come close to the performance that Iget out of my Tower. Ihave over 10 gallons through one in a GPShoestring, and it starts with a two fingeredbackward snap of the True Turn spinner.

  18. #18

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    RE: Tower 75 rpm figures?

    hi very glad to see you feel good about your tower 75but it seems some are good and -some are notif i stand corrected that is fine with me- as there is great value in this engine if it is good-but if some are good and other notthats just not good enough if you own one of these engines -please do leave a note to your feeling about the enginegood for all to know-as 75 is my favorite size for a 60 size plane-my only experience is limited to helping fellows with the engine at the field thanks
    \" The power and performance glo fuel , 15 % Morgan Omega \"

  19. #19
    rainedave's Avatar
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    RE: Tower 75 rpm figures?

    I believe these engines have shipped with two different carbs. The one depicted in the manual has a low speed needle that enters into the spraybar similar to a Webra TN. However, the carb on my Tower .61 (same carb as .75) has a low speed sleeve that rotates around the outside of the spraybar similar to many OS carbs.

    My carb works flawlessly and has never had any issues with air leaks. Maybe it's the other type of carb, as depicted in the manual, that has caused trouble.

    It would be worthwhile knowing if the problems line up with one particular type of carb. I have a feeling they do.

    David

  20. #20

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    RE: Tower 75 rpm figures?

    hi is it at all possible that -a new carb has been put on the tower 75 at some point -to correct a proir problem there-tower  does seem to have a need to get there stuff right for the custom in general- like to know -would like to purchase a tower 75- but held off as i have heard mixed reviews and carb issues
    \" The power and performance glo fuel , 15 % Morgan Omega \"

  21. #21
    rainedave's Avatar
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    RE: Tower 75 rpm figures?

    If the latest ones have the carb I described above - with the low speed sleeve - then it should run flawlessly. I bought mine three years ago and have no idea what they are shipping with these days.

    David

  22. #22
    Iflyglow's Avatar
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    RE: Tower 75 rpm figures?

    You have to push the carb down hard enough to seat the o-ring. That is the only problem Ihave ever seen with them. It is not an engine problem, but an operator problem. These .75's will run circles around any other sub $250.00 dollar .75.
    I have helped setup 5 of them now, and have never experienced a problem with them. Ido initally break them in by heating the cylinder with a heat gun to loosen them up, since they are true ABC and are quite tight. Anyone with any experience will know that a good ABC engine is tight.

  23. #23

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    RE: Tower 75 rpm figures?

    HI who makes the engines for tower GMS ?-give me some prop sizes and RPM readings -please thank you
    \" The power and performance glo fuel , 15 % Morgan Omega \"

  24. #24

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    RE: Tower 75 rpm figures?

    HI who makes the engines for tower GMS ?  MOTORMAN37 it is an engine problem if it needs attention when -new out of  the box-    running any glo engine with an air leak -will create enough heat to warp the soft  aluminum-    especially  bad at the break in as the metal are softest then and harden with the -hot cooling runs of the break in period- if it does not get broken in correctly -it will never be a great engine  and have a good long life and performance -some operators know this -some do not-  need to be handling glo engines for a while to know the info stated above-if the carb needs to be seated- it is the factories   responsible to do it correctly -not the operator
    \" The power and performance glo fuel , 15 % Morgan Omega \"

  25. #25

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    RE: Tower 75 rpm figures?

    The Tower/GMS/Supertigre/Magnum/SC and many other engines don't come with the carb mounted in the crankcase, you have actually to put the carb on it, and thats why you have to push it correctly, so in this case the responsability goes to the operator.... it is not a complicated thing to do...just make sure it is well pressed...nothing more, there are no special things here...
    Jorge Andres Estrada


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