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Engine basics => Engine set up tips => Topic started by: Bootlegger on August 27, 2007, 05:52:06 AM
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Mornin fellows,
I am flying a full fuse stunter with an OS 32 SX that we have hemi shaped the head and blocked the boost port.
Flying with an apc 10x5 prop on 5% 11-11 Powermaster fuel.
The engine starts off running real well then at about half way it starts to richen up. The tank is a metal tank on uniflow open to the atmosphere. Does any one have any suggestions ???
Randy or anyone...Thanks, Gil
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I'll assume you've checked all the usual stuff, no pinholes in the tank, no holes in the tubing.
Now, is it actually going rich, or is it losing power?
I had an LA that I thought was going rich mid way through the schedule, but it was actually overheating and loosing power as a result, it'd stagger around until the motor cooled enough to run right (or ran out of fuel).
Had me scratching my head for a few flights, until I figured out the problem.
If this is what's happening you can do two things - richen the needle slightly on the ground or add more oil to the fuel.
I'd suggest using a tacho on the ground, then when you find a setting that you like keep a note of it and a quick check on the first flight of the day will save many wasted flights
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"----will save many wasted flights". And maybe prevent "toasting" an engine. H^^
Jim
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Is this muffled SE or wrap-around header and pipe?
How close is the tank to the motor?
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Guy's, I don't think that it is overheating as I have run this engine many times in the past without this problem.
I am running a side exhaust tongue muffler, plus when flying I bring it back to the takeoff point and the engine still has plenty compression I re fuel and re start right away and make another flight. It re starts easily needles well and again about half way through it goes richer again.
I'm thinking that if I had a leak in tubing anywhere it would go lean. I was getting rust in the filter on the other tank so I installed a new one.
I was having the rich syndrom with the other tank as well.
As for the tach settings it is running between 10 Thou and 10,300 each start. I am gonna change plugs and stay with T'bolt long w/idle bar as that is what I've been using for some time in all my engines.
I sure do thank ya'll for your suggestions, and hopefully we'll get it ironed out.
As for the tank behind the engine it is about 1/2" from the back plate, and when I turn it up it doesn't go hard lean and comes right back when it's level, so that also tell's me that it isn't over heating ??? H^^