OS 46LA best mods??

As the OS 46 LA has been in use for a while now,
is there a "right" setup for these motors now,
in regards to venturi size, n.v.a. types to use,
mufflers & which ones work the best?
Fuel mixes & plug types also could be added to these
as well.

Thanks guys,
rv.

Best Mods:
1) Take out of box
2) Bolt on plane
3) Add prop, glow plug
4) Start
5) Fly

Ok, ok, I'm being facetious. A little running on the bench can't hurt.

most people add 2-3 head shims.
A .282 or so venturi with the OS Nva works pretty well.
11/4 or 11/5 props. Use the /4 with fewer head shims and a leaner run. The /5 works better if the motor is 4 cycling and richer.
Fuel in the range of 10% nitro and 25% oil, usually part castor.
Often muffler pressure and a uniflow tank will help steady the run.

These motors seem to be pretty forgiving. Once you find a combo that works well on your plane they are very reliable. Make sure you have a stiff nose on a profile. Vibration will make it difficult to get a reliable run if the fuel starts foaming.

In response to Ron's question, it is not quite so simple as running out of the box. OS has changed venturis on these engines at least four times already and can't seem to figure this out themselves. The latest (as I understand it) venturi is .295 and probably closer to utilizing all of the power available. If you have one with a smaller venturi, you may want to open it up to .290 or .295. Or get an extra venturi or two to try. (And this is with the .135 OS needle)

My own feeling is don't mess with head shims. These things vary in deck height (manufacturing tolerances) like many other engines, so there will be some differences and what one person uses may not be right for you. But you will be close. I personally don't like to mess with the internals of these because the heads of the bolts tend to strip. You can change out to the bolts used on the FP, but the LA uses only 4 bolts and they are slightly longer. The case is soft and can easily be stripped, especially if you use shorter screws.

Keep the back plate tight. Change it out to an aluminum one if you are able (Tower 40 back plate fits and is inexpensive). A front OS needle works. If you change to an ST you have to drill the case and need to open the venturi.

I am a castor oil freak. Use at least 20% oil if you want any life out of the engine, and would recommend at least half be castor. (All castor doesn't hurt.)

Use a less restrictive (and lighter doesn't hurt) muffler. A tongue muffler is fine for those who like them.

Serious question?
If i use I/2 & 1/2 20% oil , with under 10% nitro and an air filter
on a plane of the right size and weight and don,t use a speed rachet
to tur.n down the needle valve.
what kind of eng . life can I expect
I have had it with poorly built short life engines

Thanks

Here is a link:

http://www.clstunt.com/htdocs/dcforum/DCForumID1/5380.html

Alan's approach is almost spot on. The only thing I changed on my 46LA is to install a Super Tigre needle valve. I run a 11x5 prop and I can adjust the engine to do a nice 4-2-4 or run at whatever speed I want it to. I run a uniflow tank and get about 3 lean surges before cut-off.

Great engine!

I just started using one on a Time Machine 50. Stock motor, .285 venturi with ST needle assembly, sig plug, big Art tube muffler, Fox superfuel (! I have alot sitting around...) rev-up 12x5W prop, GRW 4.5 oz uniflo tank. Right now I'm getting great power and 14 laps after the clover. Very happy with this setup.

Early last Summer, Alan and I worked with Gerry Meyer on his Brodak Cardinal. Alan had loaned Gerry a used 46LA to try on the Cardinal. We tried a variety of combinations: props, head shims, mufflers (stock and tongue), venturis, 5 or 10% nitro (always Sig Champion), and a variety of hot plugs. This resulted in large changes in fuel consumption and power output, BUT we always could set it for a 'stunt run'; either a 4-2 break or a nice solid 4-stroke. Our concensus: this was most 'stunt friendly' out-of-the-box engine we had ever seen.

Lou Wollard reworks 40LAs and 46LAs, and as Lou usually kicks my butt, I certainly can't argue against his work. He probably gains consistancy and reproducibility engine-to-engine.

Try it out of the box (after an hour break-in). You can always contact a rework specialist if you can't get the run you want.

Fred

>Early last Summer, Alan and I worked with Gerry Meyer on his
>Brodak Cardinal. Alan had loaned Gerry a used 46LA to try
>on the Cardinal. We tried a variety of combinations:
>props, head shims, mufflers (stock and tongue), venturis, 5
>or 10% nitro (always Sig Champion), and a variety of hot
>plugs. This resulted in large changes in fuel consumption
>and power output, BUT we always could set it for a 'stunt
>run'; either a 4-2 break or a nice solid 4-stroke. Our
>concensus: this was most 'stunt friendly' out-of-the-box
>engine we had ever seen.

Fred;

Did you and Alan keep notes on the setup information and the results? Would make for interesting reading, and might save some of us repeated work.

Duh, notes?

Unfortunately no. The various combinations with results would have been very useful. I must remember to do this. I should keep a notebook in my car, specifically for this purpose. One of our fellow TreeTown members (Jim Schuett) always documents his testing and flights.

Fred

Install a supertigre needle assembly and a tongue muffler and go.

>Install a supertigre needle assembly and a tongue muffler
>and go.

Since OS supplied these engines from the factory with .265 venturis, .295 venturis, and several in between, and since switching to a ST needle valve (.155 diameter) will change the choke in relation to the stock OS needle (.135 OD) I would think that you might want to at least check and adjust the venturi size since my engine (if I had one) and your engine probably won't match.

LAST EDITED ON Dec-03-03 AT 11:53 AM (CST)
 
I actually posted on the results, way back when (summer of 2002). The fuel consumption was very strange.

Here is the link.
http://www.clstunt.com/cgi-bin/dcforum/dcboard.cgi?az=read_count&om=2699&forum=DCForumID1

Just reread the link. Brings back some good memories of Jerry. We still all miss him.

One thing I can tell you for sure, is by changing to a metal backplate, conventional needle valve, tongue muffler and a Supertigre aluminum prop washer, you can save a significant amount of weight. Although I don't remember the amount of weight saved, I did weigh all of these components, and was quite pleased with the difference.

Bob Smiley had somebody (Tom Lay?) mill a bunch of foof off the bypass side of the case, and claimed 1.5 oz saved. It also appears to make it difficult to determine if a .46 is a .40 or not. Could be killer in P.40!

Jimmy Johnson tried his .46LA powered Classic "Sun Devil" in 4-2-4 mode, and found my recommended 10-29 (for a brand new engine) didn't suit him. After a lot of sniveling, he tried 10-22 and is a now a happy .46LA owner. Maybe he will post his setup.

When I flew mine, I mostly used a Mac's Muffler (tuned pipe) in 2-2-2 mode, and the 10-29 worked fine for me. The 11.5 x 4 APC was the prop for my OTS, but lower pitch seemed like a good thing for a slower model. I tried it with a Big Art muffler, and liked a RevUp 11-6EW or 12-5 APC. In hindsight, I think the 12-5 would best be trimmed to maybe 11.5". Since my ST G.51 likes these same props, and the Graupner 11-6, I would certainly try their 11-6, and somebody in Canada used a 12-5 cut to 11.5. Fuel consumption is much higher in this 4-2-4 mode, and my Humongus had no room for more. Plan on 6 oz uniflow clunk tank. Very nice engine. Definitely replace the screws with a set for a Magnum XL .25>.53, Tower .40 backplate, suitable NVA and venturi. Maybe an extra head gasket. Enjoy it! Steve

why not just send it to Leonard Neumann?

"If it aint broke - dont fix it"

>why not just send it to Leonard Neumann?
>
>"If it aint broke - dont fix it"
>
>Vincent

Leonard does't need another engine he has mine.

It is worth noting that at least 2 LA46's competed at the last world champs - Igor Burger/Slovakia and Owen Rogers/New Zealand. Both of these engines showed some of the best runs there (Yes Igor, I watched your fly-off flights!) - certainly better than some of the megabuck setups or some of the specialist engines.

So the LA46 is more than capable of competing at the highest levels.

I understand that Owens engine was essentially box stock, but carefully & skilfully set up, using a normal muffler. Maybe a Kiwi or 2 would know the details - I dont have a contact for Owen.

Igors' engine used some type of pipe - perhaps you could enlighten us Igor? Whatever it used, it was darn impressive!

rv: There are virtually NO mods needed for the OS 46 LA to achieve excellent stunt runs. We have run numerous 46 LAs, from there introduction to current runs, and have had the same result with all of them.

It is NOT necessary to change the venturi.
It is NOT necessary to change the NVA.
It is NOT necessary to add head shims.

The only mod we make is to use the old OS 40 FP control line muffler (the RC and CL muffler are different) with the tip cut off and 2 or 3 3/16" holes drilled in the rear. This allows for less back pressure. This method or a tube muffler such as Randy Smith, or Richard Oliver sells works the best.

We use the APC 12.25 X 3.75 prop with 1/4" cut off of each tip making it 11/75". This prop is getting very popular with the RC Fun Fly guys, so it is usually available at most hobby shops. 5% or 10% fuel with 20% oil (10/10) should work fine.

We also ALWAYS use plastic Sullivan clunk tanks. Plumbed correctly they ALWAYS work; whether it is a 15 size profile or a big honkin' 4 stroke.

One last thing; we break our 46s in on the plane. Two or three tanks and it is ready to go. It's in the manual.

Steve I couldn't agree more with you. The 46LA requires no mods, and no break in time at all to run great. Just bolt it on and enjoy!

John

I have tried several combinations with my LA46. But the very best combination is to use a MACS muffler (Pipe), with ST NVA, 1 additional shim, and a 11 in 3 blade bolly pitched to 4. 20% oil half castor, Thunderbolt plug. Do not use pressure. This is similar to the original Scott(the macs muffler guy)Riese setup which I believe he pioneered. Constant speed runs throughout th pattern.
With this setup you can come close to the big boys tuned piped setup runs at a fraction of the cost.
Try it. You WILL love it.
Brian