stunthanger.com
Engine basics => Engine set up tips => Topic started by: Jim Morris on November 06, 2007, 07:43:00 AM
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I was wondering who might be able to retune the LA46 to make it a good 4-2-4 motor. Thats the style I like better than the high rev low pitch style.
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My friend, Lewis Popwell, has an LA 46 that was done by our own Randy Smith of Aero Products. Lewis like it a lot, and for good reason.
Randy has his info in the Vendor section.
Jim
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ADD A HEAD SHIM? ;D
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Brad - nice to see that you're a fan of "Chunk"!!!
Regarding the LA .46, quite a few of the guys around here use them and they either run a perfect 2-4 in stock form or, as you suggested, a head shim is in order.
What I found with mine was that the venturi ID seemed more critical than other engines. Once I got it dialed in, and using an OS "clicker" type needle valve, the runs were flawless with the stock head.
I mounted it on the prototype ARF Cardinal and offered it to anyone who wanted to fly it at the Brodak Fly-In.
We entered it in expert and advanced ARF and we took 1-2-3 in expert.
Gary Tultz won and it was his first flight on the plane.
Bob Z.
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I mostly ran mine on a MAC's Muffler setup, but one Labor Day, I flew half a dozen flights with a full 12-5 APC and a tube muffler that is probably a Big Art product. The 12-5 was a bit too much, but cut to 11.5, it would have been sweet (FWIW, my Dirt/Aldrich tune ST G.51 also doesn't like the full 12-5, but trimmed to 11.5, it's very good). While I liked the 12-5 on the .46LA, my test subject (Humongus) didn't like flying that slow, and the fuel tank wasn't big enough for the 4-2-4 run. I'll try it again, maybe in a Profile Cardinal with a 6 oz. tank. H^^ Steve
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Hey Bob Z. - I found my LA 46 venturi was not what it needed to be, also. Where did you end up for a size? I drilled mine out .015 but haven't been able to test it yet due to a "panzy" attitude towards cold weather!! I have a ST51 needle assembly in it.
Blessings,
Will
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Hi, Will - I have not done anything with the LA for three years but, if memory serves, the venturi ID was .290. That, in conjunction with the OS NVA (.156 OD) really did the trick.
By the way, the venturi was my own design, not thee one supplied by OS.
Also, I ran the plastic backplate without any problems. I simply removed the backplate gasket (as I do in ALL my engines) and sealed it with Anaerobic Gasket Maker - Loctite 51817.
Bob Z.
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I was wondering who might be able to retune the LA46 to make it a good 4-2-4 motor. Thats the style I like better than the high rev low pitch style.
I ran mine strait out of the box for three years and ran the same all that time. I ran 11-6 prop when the air was calm an a 11-5 when it was windy. Tank size was 4 and 3/4 oz. the plane was 46 oz.
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Thanks Bob,
It sounds like I'm in the ballpark on my 46 with the ST51 NVA. Now for spring! By the way, I also, (though they say ya don't have to,) use the same gasket goody on my tuned pipe headers. Good stuff!
Blessings,
Will
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Leo - I'm confused: "Tank size was 11 and 3/4 oz."? ???
Also, what brand of 11-6 prop did you find to work best on the LA?
Seems like no matter how much we experiment, and how accurately engines are made, there in no "One size fits
all" setup.
Many folks around here are using APCs on their LAs.
Bob Z.
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"""Hi, Will - I have not done anything with the LA for three years but, if memory serves, the venturi ID was .290. That, in conjunction with the OS NVA (.156 OD) really did the trick.
By the way, the venturi was my own design, not thee one supplied by OS.""""
HI Bob
Isn't the OS NVA a .136 diameter? This has been one of the problems people have setting up these engines
Most All of the standard size spray bars we used were .157 OD. The older OS types from the 35 and 40s used to be .157 same as the Super Tigers and PA , KK etc. When OS made the newer FPs they went to the small NVA diameter. People were used to running a .285 venturie in these type engines, but when you put in a .135 NVA they .285 venturie acts and is Much MUCH bigger, helping add to teh "runaway" problem
Regards
Randy
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Hi, Randy - the one I used was a very old one. From the 60s as I recall.
Same diameter as the ST.
I have not used the newer ones.
Bob Z.
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Hi, Randy - the one I used was a very old one. From the 60s as I recall.
Same diameter as the ST.
I have not used the newer ones.
Bob Z.
HI Bob
You most likley used one from the older FSRs , 40 or 45, good NVA , It keeps the same area inside the venturie that people are used to using in their motors. Too bad OS doesn't make them any longer or kept them at least the same size when they went to teh FP series
Regards
Randy
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Leo - I'm confused: "Tank size was 11 and 3/4 oz."? ???
Also, what brand of 11-6 prop did you find to work best on the LA?
Seems like no matter how much we experiment, and how accurately engines are made, there in no "One size fits
all" setup.
Many folks around here are using APCs on their LAs.
Bob Z.
As usual My typing and readin what I type needs a little more attention than I have been giving it. It's been changed. I think I know what the trouble is. I am over 75.I used regular Zinger. It loaded the engine perfectly with good bite.
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thanks for correcting that Leo,,
hey guys, and to think Leo judges me most of the time,, heck now I want to go back and readd my scoresheets,, lol,, LL~ LL~