Hi all,

I'm nearing the final steps building my Velocity (http://thegerhardts.com/velocity). A few weeks ago, I started the engine for the first time. After taking care of a few minor issues, I was able to taxi around for awhile. When I tried to do a static RPM test, there were a few anomalies that I'm having a tough time working out. While I'm a reasonably experienced mechanic (cars, motorcycles), I'm not all that familiar with aircraft engines, so I'm hoping the experts out there can give me some advice.

It is a Lycoming LIO-360 engine. Its a 500hr SMOH engine that I purchased from another Velocity owner who was parting out his project. The seller is an A&P who had originally purchased the engine off a wreck (it had been on a twin that some sort of crash that did not damage this engine). He removed the cylinders to inspect the crank, pistons, cylinders, rods et cetera. He indicated that he found everything ok, changed the rings and reassembled it. He also indicated that it was running fine prior to selling it to me. He seems like an honest enough guy, so I trust him on this. He also installed a LightSpeed EI on it, which came with the engine. Since acquiring the engine, I rebuilt the vacuum pump and replaced the mechanical fuel pump (although there were no indications it was faulty, it seemed like an easy thing to do while I had the engine out on a stand and they are not expensive). I also took off the intake tubes, media blasted them and repainted them as they had been painted at some point and were rather grungy looking. Other than that, I didn't do much to the engine.

I have a Catto fixed-pitch prop on it that should generate ~2150 RPM static.

So, after warming up the engine, I tried to go full throttle to see that static I could get. The first thing I noticed was that as I eased up to full throttle with the mixture full rich, the engine would sputter, and I needed to lean it out quite a lot (I'm in MA, at KORH - 1000') to achieve full power. The max static RPM I could get was ~1900RPM after leaning it out. As I said, at full rich, the engine would just sputter and it was far to rich to run well.

I've been through the engine fuel system, intake and ignition systems but can't find any issues. At full power, EGT's are only ~1100deg, #2 CHT is higher than 1,3,4 but I've heard you can't interpret much from CHT's on the ground. The actual mixture range (i.e. the throw of my mixture lever) that the engine will run well at full throttle in is actually quite narrow and is at the lean end of the mixture lever throw range. I haven't any experience with IO-360's only carberated Lycomings which run fine at full rich. Is it normal that the engine will not run properly at full rich? Any ideas what might be going on here and what I should check? Both the Lightspeed EI and mag seem to be operating properly.

Thanks.

Geoff
Velocity 173RG, N173VS
http://thegerhardts.com/velocity