flyrotary@lancaironline.net Mailing List Archive

I agree; late timing causes high EGT's (fuel burning in exhaust). Have you checked the timing marks on the ring gear for accuracy? You can use a probe through a spark plug hole & a degree wheel to find TDC, & see if it agrees with the ring gear marks. It's not unusual to get misplaced timing marks on an engine that's been modified, & any GPU modified for a/c use is pretty much a 'Frankenstein' engine built up of random parts. :-) I'm not saying that it's a bad thing, but it does increase the likelihood of pieces not matching up.

Standard practice on a/c engines is to measure oil temp at the return from the cooler. Is that where you're measuring? Actual temp in the sump is a lot higher than the gauge reading on a 'normal' setup.

Steve had a lot of good ideas (as usual) on checking instrument accuracy, and so does Skipchief below, about checking performance. Do you have a baseline for that engine & that prop for static rpm & climb rpm (from prior flight data)? I don't remember whether you have prior RVx time, but an RV will typically outclimb a typical GA plane on about 1/3 the HP, so the fact that it gets off the ground well may not mean much as far as measuring the engine's HP output goes, unless it compares to Van's published numbers for that airframe & HP combination.

Charlie

On 3/19/2014 12:00 PM, shipchief@aol.com wrote:

High exhaust temp is usually caused by retarded ignition timing. I would recommend resetting it to the base Lycoming value.

Running advanced won't help either during the initial trial period.

If you have decent air flow thru the cowl and oil cooler, you should have lower oil temps. My T-18 with O-290 barely gets over 150 in the summer unless I have an airflow restrictor in front of the cooler.

I wonder what the EGT redline value is? Are you reading a temp, or is it some unmarked value?

Also, at what phase of operation do you notice it?

Do you have EGT probes on all 4 cylinders or only one? How does the engine run, ignore the gauges, does it run powerfully and smoothly?

Leaned out 1450 degrees is fine. Rich could be 1300 degrees at full or high cruise power.

Do a google search for the Lycoming operating manual, it's not hard to find (for free) on line. it's very helpful.

The previous suggestion that the engine should speed up before dying when shut down with idle mixture cut off is correct.

Did you check the fuel strainer in the admission fitting on the carb. It's a little screen filter. If dirty and it cannot allow enough flow for full power, the engine would run lean after the fuel in the carb bowl got low. This would allow full take off power for several seconds prior to going lean.

Does the fuel line get hot in flight?

EGT circuits can be bedeviled by many application errors and a review of them at Electronic International, in the Downloads section will be a big help www.buy-ei.com "The pilot's manual for Learning and Diagnosing Engine Problems"

Good luck! My O-290 runs great!

I used it, in my T-18 to get up to speed for my first flights in the RV-8 13BT.

-----Original Message-----
From: DLOMHEIM <DLOMHEIM@aol.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent: Wed, Mar 19, 2014 4:12 am
Subject: [FlyRotary] Off Topic Lycoming Question...

Tracy:

This engine has 155 hrs on it and the cylinders were pulled and sent in for inspection and they checked out good and were simply honed and new rings added. The oil temp has been running right at 220 degrees (taken at the oil screen on the accessory case as is std on the O-290s). I have read that should drop a bit once the rings fully seat in. Next time a run it I'm also going to shoot the front two cylinders with my infra red thermometer right after shut down to see what it shows on the barrels, and I also am going to move the sender to a lower plug and see if that changes anything.

EGTs are my real puzzle though as to why all four would be maxed out. I've never heard of a Lycoming generating that hi an EGT and that was the sole domain of rotaries! :)

Thanks for your ideas on this...

Doug