Engine Overhaul

When I bought my SF260 the engine had 1,650 hours and had excellent oil pressure. The Oil filter was clean when I changed the oil. However, the oil turned black in 1 hour and was using one quart of oil every hour or two. So, in my infinite stupidity I bought 6 cylinders with new pistons and rings and valves. That was a $6,000 investment and at first it looked like I had done the right thing. The engine quit using oil and the oil stayed yellow until it was time for a change. I used mineral oil for 10 hours and then a multigrade, EXXON 10-50. However, at 300 hours STOH the valve in the #2 cylinder stuck and the push rod was bent. Also, the cylinder housing was cracked where the pushrod housing connected with it.

When the valve stuck I was 2,500 feet down a 5,000 foot runway just 50 feet off the ground. The plane would not maintain 75 knots and hold altitude. All of the grain fields around me suddenly looked like postage stamps. My back muscles contracted so much that I think I collapsed some of my spine. Then I got the gear up and suddenly the airspeed went to 120 knots and the rate of climb gradually inched up to 200 fpm. I did a normal traffic pattern and landed. I had no idea what had happened to the engine, I just knew that it was running rough and not developing power like it should.

It took the local mechanic 2.5 hours to remove the engine. It would take us 2.5 days to reinstall it once it came back for a rebuild.

So where to send the engine?????

Neil Bird and George Parker had both sent their engines off to Monty Barrett for overhaul. Most of the experimental engines had also been set up by Monty. But I did not have any first hand knowledge of where to send the engine.

The mechanic was on the phone at once. Lycoming had 3 prices. A new engine would be $32,000 and required no core. An overhaul exchange would be $23,000 or they would overhaul my engine for $18,500. This was in June, 2003. AOPA was having their yearly fly in Fredrick, MD and I went with my step son in law who just happened to be an A&P. We visited the Matatuck booth for an hour. They would overhaul my engine for $19,500 which, like with Lycoming, would include new cylinders. For $26,000 they would give me their red star engine which was fully balanced. We had already called Barrett Performance engines and had a quote of $22,500 using the old cylinders which would be reworked. I did not know what to do. Finally I called Stephen Larmore and caught him talking to Harry Sheppard. Stephen was totally unequivocal and insisted that I go with Barrett. His point was that the engine would be so perfectly balanced that it would run like a turbine. In reality, the engine was even smoother than a turbine when I finally flew it.

So off the engine went to Tulsa. I was up in Maine on vacation and was not in a hurry to get the engine back. After 8 weeks when it was ready to be tested I asked if they could install the Laser Mags. Monty said it would be no problem but he could never get Unsion to return his calls and he could get no documentation that the Laser system was certified for the SF260. John Pierce has the Laser system on his plane and felt that it was worth the effort. Neither my mechanic nor Barrett could contact Unison so we went with the rebuilt Bendix mags. I returned home on August 23 and two weeks later my engine arrived. Of course we tried to use new scat hoses but several are unique sizes and all of the original hoses are triple walled and custom made. So the hoses in good condition were reused but most were replaced. The baffling had been rebuilt and while the engine was out I replaced the boots on the nose gear push rods. All oil hoses and fuel hoses were replaced. Almost all of the bolts, nuts and screws were replaced.

The omissions from Barrett were three that I can think of:

  1. Two #4 AN nipples, one in the engine for manifold pressure and one in the left top rear of the carburetor for fuel pressure hose connection.
  2. The mags were reversed so that the delay was on the right side and required switching mags. The mechanic did this in the time it took me to safety wire two of the three prop bolt sets. I had to call Monty to find out how to index the prop fly wheel. When we finally got everything mated up we found the index marks matched up with a mark on the starter. The numbers aligned perfectly with an indexing wheel that we had taped to the prop and aligned with a cylinder stop.
  3. The adapter for the bayonet CHT was not on cylinder 6 so I had to order one from Aircraft Spruce and Plywood.
So I finally ran out of excuses to stay on the ground. There was nothing else I could do to delay testing the engine. With top plugs out we hand turned the prop until we had a flicker of oil pressure. Then we used the starter to get real oil pressure. Then, with two fire extinguishers standing by the engine was started. Oil pressure went above 100 lbs and this really upset me. A call to Barrett revealed that the oil pressure relief valve had been set using a certified gauge and the aircraft gauge should be checked before changing washers in the pressure relief valve. This caused a sleepless night. I delayed running the engine again until 3:30 pm Central. It was amazing how many things I could find to prolong the agony. I finally started the engine and checked the mags. There was nothing left to do but fly. Off I went and oil pressure dropped from 100 lbs to 80 lbs. Right in the top of the green. At idle, on the way in it, fell to 75 lbs. So for one hour I flew at 2,500 RPM at full throttle. At 3,000 feet it showed 26 and at 4,000 feet it showed 25 of manifold pressure. I do not know how much fuel I burned but I put in 42 gallons at the end of the flight. I flew for 70 minutes and it was amazing. The engine is so smooth that if I were deaf and did not look at the tachometer I would swear it was not running. There was no popping when I throttled back to land. What a rush. Someone asked if I was happy. I said that I was ecstatic. If I had it to do over again I would have simply had Barrett Performance Engine rebuild my engine when I first got the plane.

CHT ran at 200 degrees for the entire flight. Oil Temp was at 100 degrees and at one point crept up to 105 and then fell to 95 degrees. I spent most of the hour doing a race horse course above the airport and programmed the GPS III. It showed 175 to 200 knots. In level flight cross wind I was doing 183 knots. This is 10 to 15 knots faster than I did before having the engine rebuilt at similar power settings. The airspeed indicator was 10 to 12 knots below the ground speed just as it had been before the engine was overhauled. Evidently this is not unusual for the engines. However, it may be that this is accomplished by using more fuel at the same power settings. I do know that during the Sun 60 race at Sun and Fun last April I was at 27 squared and did 180 knots into the wind and 190 knots down wind coming back to Lakeland. The course is 60 nautical miles, thus the title, Sun 60 race, and it took me 23 minutes. It will be interesting to see how long this 23 minute flight takes in 2004 with the new super engine.

On landing I checked several times to be certain that the gear was down. I even looked at the mirror on the right wing tip tank to confirm the three greens that were stairing at me.

After 1.5 hours of engine operation the oil pressure gauge has started to fluctuate so much that I am afraid the oil pressure needle will break off. The problem was fixed by cleaning the inverted oil box, the kind that comes standard on the carburator engines, and putting fresh oil in the oil pressure line, back filling from the gauge to the engine. Disconnect the line at the engine nipple bacause there is a restrictor in this nipple and it would be hard to get oil through it. 9-26-2003

Air in the oil pressure line can cause an harmonic resonance to set up that will cause violent fluctuations of the oil pressure needle. I wish someone had told me this two weeks ago.

Here is the web site address for Barrett Engines.



I see that you are having trouble with your oil pressure gauge needle. Well, I had the same problem, and it is recurrent. In fact, one time my oil pressure needle fell off and I had to send the gauge back to sigma tek to have it rebuilt.

Here is what I have done. I put several restrictors in the oil pressure line. If you do not have a restrictor then you can make one by welding up the opening of a AN fitting and then drill a tiny opening in it. Next, open the oil pressure line where it connects with the gauge to bleed the air out of the system. You have to do this with the engine running. I did it in flight had had several towels in my lap and still got oil on the floor.

Good luck.....Neil Bird...