Problems getting full power from IO-360 on my Velocity

[uavmx]

I can see your logic chain as to why you think the oil in the venturi, which obviously shouldn't be ruled out. I was curious as to why you automatically ruled out ignition. I understand the EI timing is probably constantly adjusting given the atmospheric, engine power settings, etc condition. What if the mag is firing before the EI? Doesn't matter how "hot" the EI fires if the burn is already being initiated. That's why I was mentioning the data plate so he can check the mag timing.

I think by throwing out your chain of thoughts in internet troubleshooting might make the victim of the issue have an "AHA" moment, or help other people build on your thoughts/suggestions. Sometimes hearing someones thoughts on a solution can jar your memory into thinking of something else that is helpful. Or building on one idea/solution. Hell, the true is same working on these issues in person!

[WLIU]

The only reason that I would suggest that ignition is not suspect is because the original poster asserted that. So the logic chain moves to the next candidate.

The data plate for the 200hp Lyco's says 25 degrees BTDC. So that is what the magneto should be set to. That said, the way dual ignition engines work is the mixture is ignited at two locations and burns outward from those points. The flame fronts move in time intervals measured in milliseconds. Magnetos also have weaker, read colder, sparks, so the combustion process starts more slowly on that side of the cynlinder head than on the other side where the electronics deliver a stronger, and hotter spark. I will also note that the mixture swirls around the intake valve(s) and into the combustion chamber, so that that mixture is not exactly ideal throughout its volume.

What does all of this mean? At low engine starting RPM's the magneto makes a weaker spark but delivers it sooner to its spark plug. So combustion tries to get started. But the piston is farther before Top Dead Center than you really want it so compression is lower and the engine is working against the spark. Then some milliseconds later, the electronics hit the other side with a hotter spark when there is more compression, correspondingly the mixture is more ready to ignite, and the engine has less leverage against it as the piston nears top dead center. The net effect is that the electronic ignition's spark is more reliable in getting the mixture lit and the flame front moving across the combustion chamber and delivering force to move the piston down on the power stroke.

At higher RPM's the electronic ignition moves the timing of its spark ahead of the magneto so we expect that it will be the primary ignition source.

Hope the above explanation helps.

Wes
N78PS

[uavmx]

The only reason that I would suggest that ignition is not suspect is because the original poster asserted that. So the logic chain moves to the next candidate.

Wes
N78PS

I follow what you're saying and agree with what you're describing about timing, EI vs Mag, etc. But the poster only said that he was told everything was good with timing. Again, I'm just saying that with these issues you have to be open to all possibilities, obviously the poster came here because he couldn't figure it out. It's good to start at the beginning of the troubleshooting chain and not make assumptions about an engine that you never had running right (you've only been told it's running right). Otherwise you might just be chasing your ass around :-)

And now it seems the poster might have found something wrong with timing or the EI, hopefully he will fill us in with what he's found.

[Art Deaton]

I had that plbm before and found that the cam gears were 1 tooth out. no mater how I timed the mags it still would not take full throttle static test. remember you have mag timing and engine timing. Hope this may help