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Engine basics => Engine set up tips => Topic started by: BYU on July 15, 2018, 09:33:13 AM
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I have a few LA 40s that are either nearly new or new and I am considering putting them to use.
Have you got a success story using one?
What was the plane?
What prop, venturi, needle valve assembly, muffler and fuel do you recommend?
What RPM should I be looking for with what prop?
Thanks for any advice
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LA .25 intake , O.S. NVA, 11/11/10% fuel . 11x4, 11.5x4 APC or 11x4.5 TT prop . Wet two stroke , forget 4-2-4 and you will be a happier.
This is the setup we use on LA .40 ,FP .40 and FP .35 . . 10.5x4.5 works also especially if you need the ground clearance.
Brad
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I flew a Oriental ARF with the LA .40 for quite some time using the APC 10.5x4.5. It was a very good running engine and dead reliable. Several people were surprised to see that it was a LA .40. I started out with a ABN FP.40 and just had horrible results. The FP would take off and run beautifully and within 5-6 laps, it would take off like a bullet. I changed venturi's, tanks, etc. I screwed with that POS for over a month. I put the LA .40 in it and never looked back. I used a Randy Smith tongue muffler with the holes opened up to the next fractional drill size which I believe was 3/32". My tank was a ATF 4.5 Brodak Wedge running muffler pressure to the uniflow. While most don't recommend it, it was the most consistent when applied to the uniflow pipe. The tank was new but required lots of repairing. I always wanted to do a plastic clunk in this plane. One thing I noted was that I was using a 4.5 oz. tank I was barely making the pattern in the cooler months while others with the LA.46 were just using 4 oz's. I never measured my venturi as it was stock due to being a LA-S version but I believe my venturi was larger than the .25 size. I still have the engine so I will look deeper into that. I own 3 of them in which 2 run identical and the 3rd acts like that FP. Now all of my experimentation has been in the same plane with the same fuels, plugs, etc. I never checked the venturi sizes in the 3 LA .40's I own but I have always been suspicious in regards to all of them.
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I am using one with a Banshee. I use a 101/2x5 APC on grass. Currently using a 11/6 Power Point on it. Not much difference. Goes around 8 minutes on 4 oz of gas. A dizzying 11 minutes plus on 6oz. Runs great. Starts easy. I once had it worked on by Motor Man. He cleaned it and it's running great.
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Thanks Brad, Kenneth and Allen
All useful stuff.
Allen - do you know what "Motor Man" did to your engine or what size of Venturi you are using?
Thanks again
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Motorman just took it apart and crocked the piston, liner and case in antifreeze. It had varnish from castor on the piston. I thought the motor was ruined because it started to not turn right after I buried it - literally - in the ground. I had to dig it out with a shovel. I was afraid I had ruined everything. It's working wonderfully now.
I don't know what venturi it has. It does have a Smith NVA. It sure gets good gas mileage, better or equal to my 25's.
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I have a few LA 40s that are either nearly new or new and I am considering putting them to use.
Have you got a success story using one?
What was the plane?
What prop, venturi, needle valve assembly, muffler and fuel do you recommend?
What RPM should I be looking for with what prop?
Thanks for any advice
Use the engine with a .255 venturi and stock OS 20 needle, or PA Needle and .281 venturi
Head as is or 1 one extra gasket, I recommend stock as it comes first
11 x 4.5 TT Cyclone prop
use 22 percent oil fuel mostly synthetic
lock tight rear plate or replace it with metal on
Merlin 2004 plug, OS 8 or Sig RC Long
The above is an excellent proven setup
Randy
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Use the engine with a .255 venturi and stock OS 20 needle, or PA Needle and .281 venturi
Head as is or 1 one extra gasket, I recommend stock as it comes first
11 x 4.5 TT Cyclone prop
use 22 percent oil fuel mostly synthetic
lock tight rear plate or replace it with metal on
Merlin 2004 plug, OS 8 or Sig RC Long
The above is an excellent proven setup
Randy
Thanks Randy
If that’s the recipe I’ll stick with it.
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Pete Ferguson had an ARF Cardinal with a .40LA. With the stock muffler, it was nose heavy, so we put a Randy Aero CNC Tube muffler on it. It didn't like whatever prop he had on it, so we put a TT Cyclone 11 x 4.5 on. Probably PM 10-22 and Thunderbolt idle bar plug. These few changes fixed it right up. H^^ Steve
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Bob, I use two LA40s one in a Fran Twister and one in a Legacy 40. Both run great and are very reliable. I use the TT 11-4 props. On the Twister I use a 4 OS.oz. chicken hopper tank with great results. In the Legacy I use a 5 oz. Uni-Flow tank. I use the stock OS>needle valve and venturie.
Rich. PS, I also use chip mufflers with extra holes, read an article years ago, it said they run better without the stock mufflers even with the baffle removed.
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Bump, I also use the thunderbolt idle bar plugs with powermaster 10/22 fuel.
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Thanks Steve and Rich very helpful.
I flew the 11x4 and 20 size Venturi with os needle on Sunday and it went very well.
Starting was a stubborn first flick every time too.