Sunday August 17, 2025
First Engine Start! (Firewall Forward)
2.0 Hours

I had my wife come out with me to the airport today to record and look for problems with the engine while it was running. Unfortunately, I forgot to tell her I was about to start it, but she did catch it just a second after I pushed the starter. It fired up really fast!

I ran it for about 5 minutes total, checking various things and running it up to 1700 RPM once the oil had warmed up. Issues I found: neither of the alternators appeared to be working, cylinder 4 EGT was reading extremely low, and there was an oil leak from under the cylinder 4 rocker cover.

The oil was leaking from this screw that is also holding an Adel clamp for the ignition wires. My thinking is that I didn't put enough washers under it, so it wasn't tightening the cover down completely against the gasket. In any case, I took the rocker cover off completely to check the gasket, which looks fine, and then reinstalled it and torqued all of the screws. I added one more thin washer under this screw.

I took the #4 EGT probe off of the exhaust and tested it with my heat gun...it seemed to read okay. I also took the sleeve off of the splices to make sure they weren't loose...they looked fine.

The plane was idling at roughly 550-600, so I also increased the idle stop screw. I also adjusted the idle mixture to be more lean, since I think the plane was running very rich at idle.

Finally, I found a broken voltage sense wire from the main alternator regulator that I repaired. I can't tell for sure if the backup alternator is working...no broken wires, but I can't see a significant voltage increase when I turn it on with the engine running. The battery is sitting at about 12.8V, so it's possible the backup regulator (which is supposedly set to 13V at the factory) is just turned down too low.

I started the engine up again to check my fixes...the main alternator was now working fine, although the ammeter shunt was showing zero the whole time, and the #4 EGT probe read normally. It started raining at this point, so I shut down and got back in the hangar. The rocker cover oil leak was now resolved.

Later, I fired it up again now that the rain stopped. I adjusted the idle setting too far--it wouldn't go less than 1000 RPM now. The idle mixture also still seemed a bit rich. I taxied the plane over to the compass rose and calibrated the magnetometer while I had it going. It drives really nice on the ground.

As you may have noticed from the video above, the plane is idling a little rough. Also, when I did the mag test at 1700 RPM, I got something like a 200 RPM drop on each side with some rough running. After coming back from the compass rose, I also noticed what seemed like a few idle misfires and noticed the EGT on #2 drop in time with the misses. I have some troubleshooting to do with this. My first suspicion is that I've just been running it too rich and fouled some of the plugs. These are the plugs that came with the engine, so I will probably clean and/or replace them tomorrow. I'll also recheck all of the ignition wires and double check the PMAG timing.

All in all it was a pretty good day. The engine starts really well. Even starting it hot seems to be fairly easy. I only had the single leak from the rocker cover. I do want to get it running more smoothly and figure out the huge RPM drop when I do the mag check.

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