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HI Guys,

Today was the day to tune the Zenith carb that came with my Hummel 2400 engine. Since this is a new engine I really wanted to tune it as rich as possible without rough running. Turns out that the jetting won't allow the carb to be set rich enough to cause the engine to run rough. So, I just set the carb as rich as possible.

With a Prince P-Tip 54x50, WOT static RPM is 3200, the hottest EGT is 1300, and FF registers 7.5 GPH. I jammed the throttle from idle to simulate a go around and the engine didn't hesitate. And BTW, I really didn't like the little button lock cable I installed for a throttle cable. That was a little too cheesy even for me. So, I replaced it with a friction lock cable. Much better.



I could run high power only for about 1 minute without the cowl on before the hottest cylinder registered 350 and I had to shut down and grab the leaf blower.

The engine is cowled up now and I'll try and get 10 more minutes of ground running tomorrow and call it good.

One bad thing I discovered is that the secondary ignition generates radio noise. I have to turn the squelch up to 11 (out of 15) to silence it. No noise at all from the slick impulse mag. Any advice on that problem would be appreciated.



Forever Forward,

Wes

Hi Wes,
It might be a little late but I completely seperated all radio stuff from the rest of the electrical equipment to avoid interference.
Two seperate ground bus bars and two seperate positive busbars. The only connect at the battery, the negative ones do not connect to the fuselage and all are physically seperated.

Looking forward to see the video of your first flight!

Hey Dirk,

dirkverdonck wrote:Hi Wes,
It might be a little late but I completely seperated all radio stuff from the rest of the electrical equipment to avoid interference.
Two seperate ground bus bars and two seperate positive busbars. The only connect at the battery, the negative ones do not connect to the fuselage and all are physically seperated.

My radio is a handheld so I tested for conducted emissions by simply unplugging the power and running on battery. No difference. Don't know but I assume that there is some RF being generated somewhere. As an aside, the radio runs on a switching power supply that is plugged into the avionics power buss. After finishing up the ground running today I pulled the cowl and one of the secondary plug wires felt like it wasn't fully seated on the plug. I haven't run the engine again since re-seating it.

Wes

Hi Guys,

Finished up the prescribed ground running of the engine today. Even with the cowl on I could only run the engine at full power for about two minutes before the CHTs hit the 350 mark. At that point I shut down and grabbed the leaf blower. 10 minutes with the leaf blower going brought CHTs down to the 150 mark and I could run again.



The mixture is set up rich and the engine runs like it :-) Advancing the throttle slowly there are points at which the engine loads up some but it clears as the throttle is added. I did my best to get the engine to die by rapidly adding and removing throttle. I never acted like it wanted to die. Every time the throttle was advanced full the RPMs shot right back to 3200.

Here is what the exhaust looked like after the runs.




My hottest cylinder is the right rear. CHT is about 25 F. Deg hotter than the others. EGT was a bit higher as well. I checked the valve lash on that cylinder and the exhaust valve was a little tight. So, maybe ... In any event, the hottest EGT was just over 1300.

Oil pressure was right at 80 psi with an oil temperature of about 160.

I re-torqued the prop. I'll try to apply the leading edge tape tomorrow.

I also purchased a CO sensor/meter. I was concerned that since the fresh air vent is directly behind where the valve cover sticks out of the cowl I might be picking op some CO. I held the meter directly in front of the air vent and it registered 10. In fact, it registered 8-10 everywhere in the cockpit. I may try to improve that but it's not very threatening.

So, I think I'm good to go for first flight. I'll get a few hours on the engine and then revisit tuning the carb to a more reasonable mixture.

Forever Forward,

Wes

Hi Wes,
Looks good! Don't forget to install the wheel pants because you'll need every extra knot in flight to cool the engine, particularly in the beginning of the tests. (dixit John M...)
I had a hard time to keep the CHT's in the green during the first couple of hours, it's kind of normal but it gets better after a while!
I recommend climbing at at least 80 kias and not to lean during the first couple of hours.

After about 150 hrs I still climb at 80 kias or higher at a slow climb rate, in cruise I see 160 -170°C on the CHT and I lean for the EGT to be around 630°C, which is over 100°C under the stated limit. Oil temps vary between 70°C in wintertime and 90°C in summertime.

Hi Dirk,

dirkverdonck wrote:After about 150 hrs I still climb at 80 kias or higher at a slow climb rate, in cruise I see 160 -170°C on the CHT and I lean for the EGT to be around 630°C, which is over 100°C under the stated limit. Oil temps vary between 70°C in wintertime and 90°C in summertime.

I definitely be climbing at 100+ MPH after the first minute.

Those are some cool temperatures your running. Me, I just hope to never see over 400 F CHT or 1400 F EGT. Hopefully much cooler once past break in. I will run the engine pretty hard at first, as recommended by Scott, just being careful not to overtemp anything. Scott also says to run full throttle occasionally while breaking the engine in. That should be exciting the first couple of times :-)

Any way, my hope is to never overtemp the engine. We'll see how it goes.

Wes

Hi wes, call me about your radio noise!!

Hey Joe,

n502pd wrote:Hi wes, call me about your radio noise!!

Thanks for the advice. Once the airplane is at the airport I think pulling one plug wire at a time on the secondary ignition, starting the engine and checking for the absence/presence of noise will give me a good idea of whats going on.

Wes

HI Guys,

Millie and I made a road trip to Olney Municipal Airport today. Most folks who need hangar space will know that it's not always easy to get. So, sometime back when we noticed that they were building some new enclosed Ts at Olney we snagged one as soon as they were finished. The task today was to start getting the hangar set up to support the first 20 hours of Onex flying.

This is the nicest hangar I've ever rented. An end hangar with folding doors, a human door on the end, good lighting, facing into prevailing summer winds, and best of all, an insulated roof :-)



I enjoyed removing and replacing the top of my main build table.



We were there for about 4 hours today and two aircraft landed. One Bellanca and one Air Tractor.

I walked the runways. 17/35 looked and smelled like it had been resurfaced and remarked yesterday. 4/22 wasn't as nice but still OK. 13/31 is no longer maintained and is in bad shape. The only other folks at the airport were a man and his wife collecting about 100 round bails off the infield. So it's nice and mowed for the time being.

Felt kind of lonesome but probably the best place to perform initial testing.

BTW, if anyone is close to KONY and needs a place to perform initial testing, I could use some company out there :-)

Forever Forward,

Wes

Hi Guys,

Got up early this morning and re-installed the gear leg fairings. It's a real pain. I'll probably live to regret the fairings but I really like the look.

During ground running we noticed a little oil on the wing. I pulled the valve cover and found this:



Replaced it with a new one. I consulted Scott Casler and he said he prefers cork to silicon. He just considers the gaskets a consumable and buys them in bulk. I ordered 20. They are about $1.25 each. I do find myself wondering if I should drill and safety the bolts holding the valve cover on.

I gathered up oil, TCP, the torque wrench, a funnel, ... Every thing I could think of. It's about time to go.

Wes