You know guys, I have to say this is one heck of an engine I have it on a Twist 60 3D although I am not a 3D pilot yet, this engine runs awesome after the break in I tune the carb and this thing is just as good as my OS 75.. Throttle transition is perfect and has more power than my plane needs....So far I have not even used a starter on it...I have only started it with a chicken stick..So far I can't say anything negative about this engine....

I have often heard that the Tower .75 is a great engine. I haven't got anything that big yet.

It's always good to hear positive feedback about a product.

I just placed an order with Tower on Monday. Tower was running an unannounced sale on their 75 for 89.99. I added one to my order. Mostly likely I will use the engine on a Great Planes Patriot 60 or GP Phantom

The Tower 75 is one of the best values around

I have a tower 75 on my Ultra Stick 60... flies the snot out of that thing.. Runs great every time out. The ONLY thing I would complain about is keeping the muffler together.. We had a tough time at the beginning of our relationship, but after some convincing the muffler is on for GOOD now...

I found the engine to have stable needle settings and once set it was a fuel and fly engine

Often the muffler has to be fastened with a all thread through bolt with double nuts on the ends

Yup and it's cousins the GMS & Supertigres...

But what you say about the mufflers is OOOH so true!

No it is not cousins,, the Towerhobbies .75 makes considerably more power than the GMS and Super Tigre,, it is on par with the OS .75,,

tower 75 is arock solid motor,comes with a great muffler and runs good after break-in ,hauls the mail!!!!

can't say i love that engine. but hey, i'm the odd man out. had the 75 on my zen 50 and just didn't do it for me. running inverted, it was a pain to start and flights often ended with a dead stick. although i confess i'm no engine guru, i think i'm okay. i've run everything included the infamous YS and nothing, not even the local pro at the field, could get this motor running good. i still have it. maybe one day i'll use it again but for the time being i just don't have the time and energy to deal with it. slap on an O.S. and go. i've nothing but the best experiences with O.S. having owned these: 32SX, 46FX, FS-30, FS-52, FS-60, FS-91, FS-120, FS-160T. each one was a joy to own and operate.

where are these Tower Hobbies Engines made ?

The TH engines are made in China at the same factory as GMS and Super Tigre. I have a TH .75 and a GMS .76 and the power they produce is unbelievable. The GMS is a ringed engine. They both run great with a very slight power advantage going to the TH .75. The GMS .76 will swing a MAS 13x5 at 12500 rpm and the TH .75 slightly faster at 12600.

My Tower .75 came with two head gaskets installed, .004” and .0085” thick. The engine was received in January 2009.

Are two head gaskets from the factory normal? Two gaskets are more of a curious issue than a problem.


Bill

Mine just had one about .004"

Thats the thing about the GMS,TH and such-good price but you never know what you get. For 75 clams if it goes to full throttle and back it's bound to be good for something.

The Tower 75 will get a air leak around the carb real easy and then will not shut off at idle.

But that's better than shutting off when you do not want it to.

Actually they are indeed "cousins", they are ALL made in the SAME factory.


The Tower Hobbies .75 DOES NOT make "considerably more power than the GMS" .76 if anything the GMS .76 is more powerful.

I have at least THREE of both and have tested and flown them extensively.


The Tower Hobbies .46 however DOES produce more power than the slightly larger bored GMS .47 which is counterintuitive.

And I have three of both of these as well ( along with the GMS .32, .40 & 1.20 ).

Agreed

op, how does the GMS .32 run, say in comparison to an OS25FX? Thinking of getting one of the GP 1/12 scale WWII fighters and using my old OS25FP, but if it isn't enough, was thinking of the GMS .32.

I've never run the OS 25FX, but I did try the GMS 32 on a Bobcat 25... and the power on it is very good.

It compared very favorably to how much excess power I get using a GMS .76 on a Bobcat .50... this engine has gobs of extra power for that airframe.

The GMS .32 also seems to be the favored engine for the .25 sized racing plane set. If you check out their forums, you see that a lot of people favor this engine.

I notice the TH .75 main nozzle is different from the documentation with a front to back 1/16” slot on the bottom of the nozzle. The low speed needle is always inside of the nozzle, which seems to be a better design than previous. Also noticed the TH .60 and .75 carb is the same part number.

Bill

They changed the TH carbs after GMS started making the Super Tigers. The Super Tigers were always made a little like this with the slot but when GMS started making the Super Tigers they changed the slot from a "cat eye" to a straight slot milled across the outer spray bar. The TH 61/75's are done the same way.

w8ye, Thanks for the information.

The low speed needle is blunt as it is other engines. I have often thought the low speed needle should be tapered when a cat eye was not used. The cat eye on other engines probably acts like a taper but on the other part.

Seems like all blunt needle engines without cat eye should have a tendency to become rich just above idle. Increase throttle above idle goes from closed fuel flow to very open fuel flow in a very few degrees of barrel rotation.


Bill

all the newer GMS engines seem to have a very even mixture throughout the power band and in particular the Super Tigers. They do not have a rich midrange.

The newer 75's are barely perceivably rich at mid range.

I haven't been around any new TH 46's but the old ones were bad about having a rich mid range

Old thread but I hope it gets revived....I found one of these in a collection but I need a muffler extension for my biplane. Anybody know what is the OS equivalent?
Thanks
John