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O-540 Overhaul begins

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  • O-540 Overhaul begins

    I had bought an O-540B4B5 core on EBAY several years ago. It was 2800 hr never opened up out of a Cherokee 235. Back in March one of our local EAA chapter members brought John, a retiree with 27 years experience building engines at Western Skyways in Montrose, CO. He has opened his own shop where he does all kinds of work and charges $35/hr. Today I assisted him in taking my engine apart. He was astounded at how good everything looked considering the time on the engine. We checked the crank dimensionally and for runout, it is still within new limits, won't even have to be ground. Cam shaft appears to be repairable. No visible fretting on the case halves which is unusual for a narrow deck engine. Have a couple accessory case gears that will have to be replaced. Hopefully dye pen and magnaflux won't turn up any issues. Appears that Western Skyways will be able to perform any necessary work on case and crank, and balancing everything. I just bought new Lycoming cylinders and they are on their way to Ly-Con for CNC port and polish and installation of their 9:1 pistons. When I receive them will be ready to install with no further work. Hopefully in about a month we will have all the parts back and be ready to put it together. The only thing I need to buy still for the engine is one magneto. I learned a lot today. I feel very good that John wouldn't okay any part in the least bit questionable. It will be an experimental engine but built to certified specs.

  • #2
    Great - very educational doing it yourself, I bet it will be a pleasure too.

    For my 2c, I would definitely replace the cam shaft while you have the engine open. It seems to be the weak link on well used Lycoming engines, particularly ones which have sat unused for several years. There's no telling how bad the inter-granular corrosion will be on the lobes, and you can't necessarily grind it out or even detect it until the part starts to fail prematurely. Replacing the cam shaft is the cheapest insurance you can buy.

    Comment


    • rodsmith
      rodsmith commented
      Editing a comment
      I'll talk to John about the camshaft again. He had originally indicated new was the way to go until he saw how good this one was. He also mentioned something about it having a better cam profile (higher lift) than the new ones. I looked at the logs again, engine was new in 1963, lycoming does a lot of things different now, meaning some parts have to be replaced just because they are obsolete. One example was the rod bolt nuts are secured with roll pins. The rods will require some minor machining for the new style nuts.
      Last edited by rodsmith; 06-12-2018, 11:07 PM.

    • Battson
      Battson commented
      Editing a comment
      An expert would know best. If your engine is from the desert then corrosion may not be a key concern.
      Last edited by Battson; 07-12-2018, 05:16 PM.

  • #3
    Got the case and crank back. No issues with them. Camshaft back from grinding. $200 vs $2500 new. Waiting for new cylinders to return from Ly-Con cnc porting. I'm facing a major decision. All along I had planned on one mag and a Lightspeed ignition. I ordered a slick mag and harness from a place that was considerably cheaper than Aircraft Spruce. I got an email back from them saying the price had gone up, was now the same as Spruce. The price includes a core charge of $250 as does Spruce. I don't understand how they can charge that on a new product. Anyways the total price of a magneto, harness, and plugs is $550 more than a 2nd Lightspeed ignition which includes everything. A rebuilt magneto doesn't save much because they have a $500 core charge. I want to go with dual electronic ignition but have some reservations. I already have a robust electrical system planned with 2 alternators, would add a second small battery. I just still have some concerns about an engine dependent on electrons.

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    • #4
      Rod,
      EI uses very little current, even a small backup battery will run one for several hours.
      One EI gets you probably 80% of the benefit of dual EI. You are only getting a small additional benefit by using dual EI. Up to you obviously, but with your electrical redundancy, I wouldn't worry about electrical failure causing your engine to quit. I believe Lightspeed even sells a dedicated EI backup battery.

      If your two alternators and 2 batteries all fail simultaneously, I would guess whatever is going on in your airplane will having you dreaming about being safely on the ground as quickly as possible anyway.

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      • #5
        Sounds like a great deal on the engine. Hopefully it works out great.

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        • #6
          Other considerations in favor of dual EI, magneto requires overhaul at 500 hr. EI requires work at engine overhaul time. Spark plug replacement is much cheaper with automotive plugs.

          Comment


          • #7
            Yeah, all of that.

            The older we are, the more we tend to trust mechanical stuff over electrical. I have worked on enough stuff during the transition to trust electrical stuff more than mechanical, all things being done to a high standard.

            One of the few regrets on my build is not being involved in the engine rebuild. Although, based on the amount of scrap I am creating, maybe that was a wise choice.

            There are a couple of great "polls" in the electrical section of VAF. "Alternator reliability" and "broken alternator belts". Lots of good info. Last time I checked, of those who responded,no one had ever experienced a belt failure.

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            • #8
              Originally posted by rodsmith View Post
              Other considerations in favor of dual EI, magneto requires overhaul at 500 hr. EI requires work at engine overhaul time. Spark plug replacement is much cheaper with automotive plugs.
              Funny you should say that, buddies of mine were taking their Maule M5s into the backcountry today. Lost a mag in-flight just out of home base, and now the whole trip is cancelled.
              Glad to have replaced our mags with EI mags from Surefly.

              Comment


              • #9
                I have flown with dual Lightspeed on a Lyc O-235 for 14 years...a great system. I am going with an updated dual Lightspeed system on my Bearhawk. Some of the new features make it an improvement over what I have been running.

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                • #10
                  I ordered the dual lightspeed this afternoon. Got thinking about the number of light sport planes now shipping with dual EI. Cubcrafters is one that comes to mind.

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                  • #11
                    Or you could try the 6-cylinder Pmag which is going into production soon - oh, wait..........

                    Comment


                    • rodsmith
                      rodsmith commented
                      Editing a comment
                      I think I have heard that story for 10 years now.

                    • JimParker256
                      JimParker256 commented
                      Editing a comment
                      Too funny, PaulSA...

                  • #12


                    Is this change going to effect the basic design of the electrical system in your build? How are you going to wire the ignitions?
                    Brooks Cone
                    Southeast Michigan
                    Patrol #303, Kit build

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                    • #13
                      I already have two alternators in my system due to an all electric panel. I will be adding a 2nd small 6 AH battery. I will wire the ignitions directly to each battery like Klaus recommends. The second battery also eliminates the problem of the EFIS resetting during starting due to voltage sag, while you are trying to watch the oil pressure.

                      Comment


                      • #14
                        All the parts are back, reassembly is on hold for a few weeks while John is working some other jobs. Picture is of cylinder intake with Lycon CNC porting. The ridges made by the machining are left, they act like the dimples on a golf ball to increase air flow. In the exhaust port they are smoothed out so they won't catch exhaust residue. Lycon says 6HP gain per cylinder, and that is dyno verified. Also is an efficiency gain, so less fuel for same power. Also had them strip and alodine cylinder heads and paint the barrels black which they say provides the most cooling benefit.

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