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Rough running at low idle

PostPosted: Sat Feb 17, 2024 3:10 pm
by VillaAir
New to me SONEX ONEX.

Aerovee 80hp runs rough at low idle.

This engine has been sitting for a couple of years.

Any hints at tuning it up after sitting so long?

Also noticed that the intake from the Aeorvee inject to the heads is wrapped. Is there a reason to do this?

Re: Rough running at low idle

PostPosted: Sat Feb 17, 2024 5:18 pm
by XenosN42
What is the 'low idle' RPM? New AeroVee engines will idle well at 900-1000 RPM, anything lower than that may cause rough running. As the engine breaks in you may see smoother running with RPMs as low as 700. But your mileage may vary.

More importantly - how does it run at higher RPMs? That's what really counts. There is a method in the manual to turn the AeroInjector. Many people have great luck with that. However, I prefer the method described here: http://sonex604.com/aerocarb_thoughts.html

My intake manifold from the AeroInjector to the cylinder heads aren't insulated. I don't see the need. However, I can't imagine it would hurt anything.

Re: Rough running at low idle

PostPosted: Sun Feb 18, 2024 11:37 pm
by karmarepair
XenosN42 wrote:My intake manifold from the AeroInjector to the cylinder heads aren't insulated. I don't see the need. However, I can't imagine it would hurt anything.


Those instakes run COLD, insulating them keeps them COLDER, and the fuel MORE likely to condense out of the mixture onto the manifold walls, leaning out the mixture. This is why you often see manifolds wrapped with oil lines; the heat from the oil helps keep the fuel particles in suspension, if not completely vaporized. The OP should remove that insulation. LET them pick up heat from the exhaust and the heads. But wrap the fuel lines into the Aeroinjector, by all means, as they typically run way too close to the exhaust.

Re: Rough running at low idle

PostPosted: Sun Feb 18, 2024 11:40 pm
by Bryan Cotton
I needed to enrichen my mixture a little bit, because in the cold at full throttle it was going over 1400F full rich. So I did a quarter turn rich on the needle carrier. That was way too rich - and the idle was horrible. So I might suggest trying to turn your needle leaner a bit.


Before this adjustment it started and ran awesome.