• If you are new to GiantScaleNews.com, please register, introduce yourself, and make yourself at home.

    We're 1st in Giant Scale RC because we've got the best membership on the internet! Take a look around and don't forget to register to get all of the benefits of GSN membership!


Inside the Roto 85FS


The left side pushrod sleeve seals were leaking on the engine in my Champ, while the plane is down for refinishing I planned to replace the seals. I ordered a gasket set from Vogelsang Aeroscale some time ago. The cylinder head must be removed to accomplished this task. I have possibly an hour on the engine which was bought new while building the Champ, the pushrod sleeve seals had leaked from the very beginning.



In order to remove the cylinder head 8 mm nuts, I had the turn down a socket to fit into the head, a twelve point socket may have worked but I don't own one.



As stated there is about an hour on the engine. I was surprised at the carbon deposits on the cylinder head, the cylinder bore looked great however. Once the head is removed the pushrod sleeves can be removed. The sleeves are sealed with "O"rings on each end. I using Red Line racing oil mixed at 30 to 1, a 30 to 1 mixture was recommended in the original manual. When the second engine for the Cherokee, that manual recommended a 40 to1 mixture of Motul 800 oil. I checked the latest manual on the Roto web site and they are now recommending Sthil HP Ultra at 50 to 1. This engine does put out some oil so I am switching to Ultra.

IMG_2543 (1).jpg


The new head gaskets are somewhat convoluted as seen in the photo on the right and get compressed flat when the head bolts are torqued to 42 inch pounds. I had to borrow the old trusty Snap On dial torque wrench from my brother's auto repair. I'm pretty sure my dad purchase the wrench in the 50's. We used it back in the day to adjust bands on automatic transmissions. I checked the valve lash on the this head and it was at spec, .004" intake, .008 exhaust. I decided to check the other side and found both valves were loose. I retorqued the head and adjust those valves to spec. It's ready to go back into the Champ, hopefully it doesn't leak!


  • IMG_2550.jpg
    2.5 MB · Views: 118
  • IMG_2552.jpg
    1.7 MB · Views: 144