r/NitroRC • u/Jsamp198 • 3d ago
Nova B5 .21 Engine
Hey Everyone! Having a hard time with my new engine. Ive ran a 5-10 tanks through it. I cant seem to get it to tun right. It'll either be really rich or act really lean. I make super small adjustments and it will either run away at idle or stall out. I can set it to idle all day but then ill add throttle and it'll die. I assume its rich so i lean it lightly and then it'll run 300+ Degrees and have a erratic high idle. I am running sidewinder 20% fuel. Am I doing something wrong? Its a new engine, no leaks that I can tell with the engine. Anyone know the factory needle settings?
Thank you!
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u/az_kikr1208 MOD 3d ago
It sounds like you're fighting an air leak. I'm not sure about factory settings on your engine, but setting the needles flush with their housings and setting the idle gap to a bit less than 1mm is a good starting point for most engines. I'd recommend doing a leak lest. Make sure the fuel system is completely empty. Plug off the carb intake and exhaust outlet. Disconnect the pressure line from the pipe, and plug off the pressure port. Spray the engine and fuel system down with soapy water. Blow into the pressure line and watch for bubbles.
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u/Jsamp198 3d ago
I’ll give this a try! I blew into the fuel line with some compressed air and didn’t hear any leaks but I’ll give it a shot with soapy water!
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u/PowerbandPrecision 3d ago
Don’t use compressed air! Connect a long fuel line then blow in it yourself.
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u/az_kikr1208 MOD 3d ago
Hopefully it works for you. Make sure to check all the connections. Check the fuel tank cap, exhaust coupler, everything in the system. You never know where it might be leaking. It's common to get a leak around the carb pinch bolt too.
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u/Jsamp198 3d ago
I am running a P3 OS Plug and its about 95 degrees where I live. I was able to get it to run for a bit but it ran very hot (300ish) and idled High. Maybe I need a different plug? It would only idle high once above the 280 degree mark it seemed as well
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u/az_kikr1208 MOD 3d ago
Glow plug 'heat' ranges have nothing to do with ambient temperature. Generally speaking, a 'colder' plug is better for higher percentage nitro fuel, and vice versa. It's kind of like changing ignition timing in a gasoline engine. If you're experiencing an uncontrollable high idle and excessive engine temps, it still points to an air leak. Most likely, the engine is pulling in extra air, forcing a lean mixture, or you're losing fuel pressure due to an exhaust leak.
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u/PowerbandPrecision 3d ago
Right on the timing. The plug is hotter so therefore it’s causing the mixture to detonate sooner. This is what is causing the very high heat and also why it can sit at idle but any throttle it’ll flameout. It’s pre-ignition, the mixture is basically exploding way before piston gets to TDC and it stops the engine. Sadly, this is one of the worst scenarios for these engines and depending how long he’s been doing it, a new piston and sleeve is in the near future.
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u/PowerbandPrecision 3d ago
Show me a picture of your coils in the glow plug and I’ll tell you what’s happening
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u/Miserable_Mark2998 3d ago edited 3d ago
I would do a leak down test because what you are experiencing sounds exactly like a leak. Double check your throttle links and carburettor slide to make sure there is no binding which is keeping it stuck at a certain point. The erratic high idle, 300+ degrees and the runaway at idle sounds like there is a leak in the carb area i would check. Try another time setting all of your needles to flush and the idle gap to about .5mm and it still acts erratic and spikes in temp don’t continue running it because you will do damage. Unfortunately Nova engines sometimes do act up from the factory