I'm putting my old Viper 500 Quickie back in the air again, and I need an engine.

I'm looking at the TH .46 engine. I own 8 of the TH .75 engines and have had very good luck with them. Only 1 engine had to be sent back for service after 20 months of running the crap out of it. I think I just wore it out.

I've read some pretty nasty stuff on here about the TH .46--and I've read some really good stuff from people whose opinions I put a little more faith in than a lot of other guys.

Whats the word? Was it just some of the early models had a problem and now it's fixed? Or is it a QC problem and still an issue?

I'm a pretty good engine guy, and I don't mind it if I need to replace a seal right outta the box if thats what it takes--I just need to know if anyone can point to a specific problem.

Please don't take this as a trolling thread. I really want to just slap my Viper together and burn a few holes in the sky. Tower has a couple .46 engines on the S&D page for cheap right now--so I was thinking about buying one.

Thanks

I've owned three of them. They ran perfect. I sold them to guys that think they are great. They've never given anyone a minutes trouble. A guy came to the field with one that he said wouldn't run no matter what. I removed the Fox idle bar plug and installed a Tower Power plug. Tuned it up and he flew it the rest of the day.

I don't see that they are any different than your experience with the 75's.

A couple of friends have had a GMS 47 between them and that engine has always run fine also.

Enjoy,

Jim

Like you, I have a couple of the Tower .75's and they are really good engines. I have a 46 that was a bugger to tune until I figured out that the low end is pretty sensitive. SMALL ADJUSTMENTS ONLY PLEASE. The other issue, going lean in flight was cured by sealing up the muffler pieces with high temp silicone and high temp lock tite. After that mine is still burning up the sky on a shrike 40. This same 46 was on my wife's trainer until she begged for a 4 stroke. It seems like the Tower 46 is like the Magnum 46 and 52 in that the carb really likes small adjustments. Good luck and enjoy

I've had a Tower .46 since they first came out and haven't had any trouble. It's old and worn, but I have it on a seaplane because it's so reliable. I have it in a Fazer on floats and when I want to float fly, I grab it, pour in some fuel, flip the prop and I am 99% sure I'll get reliable operation from the Tower. A couple of other guys have them and they keep chugging on. Plenty of power, too. Plus, they come with a Tower muffler.

It's not sexy like a new OS and it's pretty cheap, but it has a rear needle that works, it starts easily by hand and doesn't quit out on the lake.

I don't know about your field, but there are some guys at my field that can't tune an engine to save their lives and are also vocal. I found one person who couldn't get a TT .46Pro to run right and ended up opening the main needle 3/4 of a turn! 3/4 of a turn. Dang was he lean. These guys who tweak every flight for the very last rpm are always complaining in my experience. I haven't touched the low end of my Tower .46 in maybe 5 years.

The Tower .46 would not have hung around this long with people buying them regularly if they weren't any good.

Is the TH46 really that bad? In a word no.

But it is a bit tempermental. Like already mentioned
the needle adjustments are a bit sensitive so its easy
for the average "needle tweaker" to miss the sweet spot.

I think where most guys go wrong with this engine is
inadequate break in. Its very tight so needs considerable
time for break in. What they end up doing is run it a little
on the ground then set it just slightly rich and fling it up
in the air. It then proceeds to lean out in the air, overheat,
and usually die. After a few deadsticks the owner proclaims
the engine junk. Usually with less than two or 3 tanks of
fuel through it.

You can get by with this with most OS engines but others
Like the Tower require a little more care.

They lean out a lot in the air. More so than most other engines.
And the needles interact. They are screamers once you get
them dialed in correctly.

Mike Hammer

I've noticed that my TH .75 engines are a bit funny on the carb too.

After a good break in--I set the low speed for instant throttle response--and then I'll never touch it again. No reason too.

The high speed needle is funny. It must be the taper on the end or something.

The engine doesn't really like to be set rich enough to hear the RPM drop off. I peak it and then back it off about 6 or 8 clicks and then go fly it. I point the nose up to check for a lean condition. No problems. But, if I actually back it off enough to hear it get a little rich and start dropping RPM--then it's slobbery.

I've got a damn good ear for a 2-stroke. I never use a tach. I can tell when they are lean or rich by listening to them as I tune.

You can always tell when you've hit max lean because you'll click the needle 1 more time and it won't gain anymore RPM. Then click it a couple more times and nothing happens. But--you click it again--and it sags and slows down. I can hear that with my ears and feel it in the needle when I'm tuning.

So, I find that spot where you give it that first click and nothing happens. I kow I've just hit max lean and max power. So, I back it off 6 or 8 clicks. The engine doesn't slow down. Most glow engines will slow down when you go 8 clicks rich from max lean. Not the TH .75. Not mine anyways.

I've got 8 of them. 1 is in the box and 1 had to get sent back for service. So--I've got 6 of them up and running. They all act the same way when tuning.

Anyway--when it's 8 clicks rich--it'll run fine. Point the nose up and it'll pick up maybe 100RPM and hold steady for a whole tank if you hold it there.

If I keep going rich untill I actually hear it slow down--they run like dog poop. Too rich. Slobbering and burbling. It effects the transition too.

I guess--what I'm saying is that I'm used to tuning finicky engines now. I'll bet the .46 is similar to the .75

It's gotta be the way the taper is shaped on the end of the needle. Maybe it's a really narrow taper. Or a very steap taper that drops off real quick.

My mind tells me that it's a narrow taper. You can keep tweaking and tweaking--you'll get small changes in RPM as the needle goes in or out. But, when you get too the shoulder on the needle--then it gets real sensitive because your off the taper and into the straight part of the needle shaft.

I don't know[:-] I just know they are kinda finicky. I been ramblin'. Sorry.[]

Break in?

I got my own method. Lots of voodoo and black magic.

But, it works.[8D] I don't have a turd engine in the entire hanger. Of course--my entire hanger consists of TH .75 engines. Thats the only glow engine I have now. All the rest of 'em are gassers.

I actually took a TH .75 OFF an airplane because when I broke it in--it was the best runing one I've had yet. I put it back in the box and put a new TH .75 on that plane. It doesn't run as well as the one I took off.

I basically break them while they are screamin' at maximum RPM with tiny props and extra oil in the fuel jug.

Got ear plugs?[:-]