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Author Topic: La 46 r/c to c/l  (Read 1792 times)

Offline John KruziK

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La 46 r/c to c/l
« on: February 03, 2011, 06:00:03 PM »
What needle valve and venturi could be used for this conversion. And where is a good place to buy.Thanks
« Last Edit: February 03, 2011, 06:50:27 PM by John KruziK »
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Offline RandySmith

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Re: La 46 r/c to c/l
« Reply #1 on: February 03, 2011, 06:31:59 PM »
Quote from: John KruziK on February 03, 2011, 06:00:03 PM
What needle valve and venturi could be used for this conversion. Thnks

You can use the stock Venturie with an OS NVA  or a PA NVA

Randy
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Offline Geoff Goodworth

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Re: La 46 r/c to c/l
« Reply #2 on: February 04, 2011, 01:10:48 AM »
Pat Johnston and his mates are using the factory OS FP 20/25 venturi (OS Part No 2231 2000) 6.55mm (.258") dia with a 4mm dia ST-type NVA. One of our club mates runs the small venturi that used to come with the FP 35 and FP 40. That's 6.76mm (.266") dia with the factory OS NVA (OS Part No 2231 1000).
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Offline Kim Mortimore

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Re: La 46 r/c to c/l
« Reply #3 on: February 04, 2011, 11:35:05 AM »
Quote from: John KruziK on February 03, 2011, 06:00:03 PM
..... And where is a good place to buy.Thanks

towerhobbies.com for OS venturis and needle valve assembies.  The LA46 is being run in our area in a variety of setups and they all work.  Very versatile, user-friendly engine.   
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Kim Mortimore
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Offline Steve Helmick

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Re: La 46 r/c to c/l
« Reply #4 on: February 05, 2011, 06:37:53 PM »
Just call Randy Smith. He'll have venturi in several sizes and his NV Assy.'s are THE BEST. I do NOT like OS NV Assy.'s! Get one of his CNC Tube mufflers, while you're at it. Put a "rubber ducky" on it.

I believe I have a .272" venturi (home made) in my .46 LA. It's an early engine from when they only came in R/C form.  Runs great. I use the Randy muffler with muffler pressure, Thunderbolt R/C Long glowplug, 10-22 Powermaster, and 11.5 x 4 APC. The backplate is from a Tower .40, and the screws are all changed to socket heads.
I just believe in setting an engine up for total reliability from the git-go. It is that... #^ Steve
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In 1944 18-20 year old's stormed beaches, and parachuted behind enemy lines to almost certain death.  In 2015 18-20 year old's need safe zones so people don't hurt their feelings.

Offline Geoff Goodworth

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Re: La 46 r/c to c/l
« Reply #5 on: February 05, 2011, 07:53:46 PM »
Steve, I know you don't like the OS NVA and to each his own—no argument.

However, I'm unaware of anybody in OZ who has bothered to drill out the crankcase and venturi for the 4mm dia spraybar even when we have Steve Rothwell at the field with a range of different sized ST-type NVAs almost every weekend.

Remember the FP 20/25 venturi and the OS NVA are a simple screw-in.

I agree with changing the screws to cap heads and I changed the backplates on mine because I had them and the plastic backplates fell out and the gaskets came loose while I was removing the rear needles and backplate screws on the two that I bought.

I was surprised at how little tension was on the backplate screws from the factory but I am sure they seal the nylon backplate. I can also understand why people who are used to tightening the backplate screws really tight on an aluminium backplate could have trouble with the distortion on nylon one.

I was also amused to find that the factory, cross-head screws were exactly the same length as the 12mm cap screws from Micro Fasterners that I replaced them with and definitely not 11mm like Tower claims they are.

Cheers, Geoff
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Offline Bill Little

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Re: La 46 r/c to c/l
« Reply #6 on: February 05, 2011, 08:11:01 PM »
The available OS parts work fine for the NVA and venturi.  And that is coming from a guy who uses PA NVAs in almost everything!  With out a doubt, a PA NVA is the best on the market, bar none. Period.  But for the purposes of an OS .46LA, the stock one is all that is needed, plus it is a"drop in". ;D

I *think* I agree with Geoff, if he said he replaced the back plates with metal ones.

Why? Because I have seen more than one LA engine with a cheap plastic back plate leak.  ONE was enough for me.  Yeah, people say they never have had trouble and that is FINE!  But I used to know a fellow who let Semi Tractors run over his chest, and he would get in a car and let it be blown up with Dynamite.  I wouldn't.............

Why risk the problem?  The metal back plate is cheap, and a no brainer to use, especially when in comparison to the crap you will go through if the plastic one leaks. ;D

Big Bear
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Offline Geoff Goodworth

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Re: La 46 r/c to c/l
« Reply #7 on: February 05, 2011, 11:46:27 PM »
Bill, aggree 100%. I bought a couple of OS backplates from Tower when they were running out the FP parts—just in case.

Unlike the Australian government, I put something aside for a rainy day— ;D VD~ S?P —and haven't we had a few of those lately!

The thing that amazed me was how the screws in the backplate were nipped up just tight. They were easily removed and I think that's where all the problems come from. The natural tendency is to tighten the screws more than is necessary thus distorting the plastic backplate. I believe that screws in the plastic backplate should be tightened using a screwdriver-style hex key held in the fingers only but tightened as much as possible without going to a closed fist grip. A steel flat washer will probably help as well.
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Offline Steve Helmick

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Re: La 46 r/c to c/l
« Reply #8 on: February 06, 2011, 07:17:12 PM »
The OS NV Assy. works fine until you crash it just right. Then, it looks ok...most would have a tough time justifying to throw it away. I'm not sure what the problem is, but they look fine and don't work worth a darn. The ST and PA NV Assy. will either work, or it's obviously broken. Which reminds me...I need to put (at least) a new PA needle in my Magnum XLS .36 after the last outting.  :-[ Steve
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"The United States has become a place where professional athletes and entertainers are mistaken for people of importance." - Robert Heinlein

In 1944 18-20 year old's stormed beaches, and parachuted behind enemy lines to almost certain death.  In 2015 18-20 year old's need safe zones so people don't hurt their feelings.

Offline Kim Mortimore

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Re: La 46 r/c to c/l
« Reply #9 on: February 07, 2011, 11:49:55 AM »

As an habitual overtightener, I find that a drop of Loctite or other thread-securing goo helps reduce the temptation to see how much torque it takes to strip threads in soft LA aluminum (or "aluminium" for Geoff's benefit).
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Kim Mortimore
Santa Clara, CA

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