Using steel wool, I removed the rust from all steel pieces including the cylinder, crankshaft and piston. I also removed the sand blasted surface from the aluminum, then applied Mother's Mag and Aluminum polish to removed the steel wood brushed look from the aluminum.

Engine doesn't exhibit heavy wear and where internal corrosion occurred wasn't in critical areas that would affect compression, cause leaks or compromise mechanical strength on machined surfaces. It should be a good runner with good mileage left in it.

I deviated from its historical appearance by painted the head green. With it cleaned up, the surface corrosion defects are more apparent. The green makes it my special engine. I replaced the factory screws with stainless steel Allen cap head screws.

To expedite assembly, I substituted Permatex Ultra Grey RTV to seal the cylinder to crankcase and to head gasket areas. If compression is too high, I can manufacture gaskets for it later.

I'm pleased with the results. The screws are just set to allow the RTV to cure. After, I will torque them down. Some time near future I will bench run the engine.

George,

A labor of love, for sure!  It must have been used as a surf casting fishing weight to cause corrosion and rust like that.

Pretty amazing what you did with it. I was surprised at the satin surface of the case, when I read your last step was mag polish. What did you do different that made it satin and not shiny? Also, did you re-blue the cylinder fins. They look really clean on the finished engine.

Every time you fly it, you can say that it absolutely would have ended up in the junkyard--except for your rescue. Great job!

Dave

Thanks for the added info, George.

Hope you enjoy your "new" greenhead.

Dave

Or just left in some unheated space in an area of the country subject to humidity and temperature swings?

Tim, it could be a barn find, we'll probably never really know. The good is, now I have an unusual and interesting story to tell, not much different from someone who restores an old rusted out barn find car to its former glory. It is an example for others. Now they know that even though an old engine may appear in the rough, that further investigation may reveal it is worth saving with additional work and be put to good use.

Also I learned further that tell tale signs from the photos, had I been more careful to review, would have revealed to me as I am sure as others, that this might be a problem engine to start with. Not sufficiently familiar with factory metal casting occlusion defects, I bit. A further look at the seller's photos, the head screws have no zinc or black oxide or rust. Old zinc screws will rust over time due to air humidity. They are too clean and too bare steel in appearance, which indicated they were media blasted.

Great work George!
It's nice when you can bring them back from the dead and get them running or even better again get them flying a model, a very satisfying feeling.
Have restored many old engines myself but sometimes you get one too ruined with corrosion in the wrong places or breakages you can't fix or missing critical parts and end up in my parts engines box waiting hopefully for that vital part...oneday.


Regards Gerald

Got another Stallion .35 from the bay. This time, when I rotate the piston, it has subport injection (gap between piston skirt and lower edge of cylinder exhaust port.  Nope, a previous owner installed the piston and cylinder 180 degrees. The piston cross scavenge fence is on the exhaust side instead of the intake side, head is reversed too.

Engine is otherwise fairly clean outside. There is faint signs that it was mounted at one time, but the markings are light. It doesn't need a complete tear down, just reorient the cylinder, piston and head. Then a light exterior cleaning.

Got it apart by carefully tapping the edge of a pocket knife blade to ease off the head, then using a flat screwdriver as a drift, gently tap out the steel fin cylinder from the bottom of the cylinder with the backplate off.

Gasket in head seems to be reusable, left in place. Interesting how the intake side of the combustion chamber is completely filled by head at TDC, pushing mixture to combustion side of the fence. Noticed combustion side is sloped back toward intake, to keep fuel charge from exiting until combusted. Perhaps why this engine doesn't do the 4-2-4 break?

Such a thrill when an engine is torn down and restored to running condition after the owner didn't follow indtructuins or ask for help.   One of my better Fox's was one someone bent the push rod on trying to disassemble it.  Losy count o number of engines that I have brought back to life.  Even those with low compression.  Nothing like an electric finger and 3-n-one oil.

Yes, I agree, John. I enjoy it when I am able to fix another's problem and put the engine back to good use. 6 years ago, I got a used Enya .19-VI TV for a bargain. However, when I received it, had a bent prop shaft. The prop wobbled when mounted. It was also missing the prop nut and washer, found one that fit in my motorcycle salvage parts bin and a fender washer in my hardware bin. Drilled / reamed the washer to proper shaft size. Took my plastic faced beater hammer, gave the prop shaft a couple sharp whacks while rotating the crankshaft, until I had no perceptive runout.

Lo and behold, I was able to straighten it, put a 9x4 prop on it on the test bench, bingo! Ran without a hitch even to full throttle. Engine has like new compression. Be a good engine on my Robin Hood 25.

Chuck, sorry to hear about your Fox .35 Rocket grenading on you. Stuff sometimes happens.

I read recently of a man who cowled his OS Max .30 Wankel on a scale cabin job after successful use on an Ugly Stick. Cowl had insufficient cooling holes. Engine runs hot, OS warns about adequate cooling, cowling should have twice the exit ventilation as entry. Turned an expensive engine into a paper weight after a couple flights. Seriously overheated, it lost compression, no doubt ruined the fine fitting machined rotor. (Has no rotor side seals, only apex tip seals. At least he didn't bite the big one like the R/C turbine engine guys; one Figure-9'd his $30,000 twin engine with a realistic fireball ending.)

Also interesting according to article on Sceptre Flite, Peter Chinn's write up, the earlier versions prior to the PII has a precision ground Meehanite rotor (just like our iron piston steel sleeve engines) and steel chamber parts. Those, it was recommended to run 25% Castor oil fuel and mild nitro (just like our earlier engines, too).

Would love to have a Wankel, but they were close to $500 new. Now on the 'bay, they are commanding ultra ridiculous prices, new close to $1K. My stash of K&B's, Enya's, HB, Fuji, OS, Cox, OK, Thunder Tiger, Magnum, Sanye, Norvel, Fox, Gilbert, Testor's Red, Blue, Black (Series 21) and plain (old man McCoy's pre-Testor) engines didn't cost near that at all.

Speaking of checking an engine's internals prior to running like your Fox .35 Rocket, Chuck, back in the mid 1980's, I bought 2 Fuji .099S-III R/C engines on closeout from Hobby Shack for only $10 each new. I took them home, removed the back plate. They were full of metallic swarf. I further disassembled them, and flushed the crankcase and parts with solvent, before reassembling them. If I ran them as-is, it would have ruined them. Something happened to the Fuji factory in Japan before they folded. Guess they were so pressed on putting out engines, they were just machining and assembling without cleaning.

First time I posted about an engine I rescued 4 years ago, but since I originated the thread and this engine was also a Stallion, thought I'd save some server disk space and continue the thread post Covid.

Also got another Stallion, this time an R/C one. It seems to be a low mileage one also, but missing the exhaust baffle for mufflerless good idle. Next will be to run a bench test of these two I repaired. Also got another Testor .35 Red Head I picked up off the 'bay for under $30 shipping included. Will post about it in another thread. Also picked up a Testor .35 Blue Head R/C during Covid.

Nice work! Is that the original NVA?  C R  P.S. Are you in Northern NM?

Thanks, NVA is original and the needle too, just missing the spring ratchet. No, bordering middle of Texas Panhandle, 95 miles northwest of Lubbock, 95 miles southwest of Amarillo, and 95 miles north of Roswell. Rode my motorcycles a number of times to Chama up north near Colorado, but that is an 8 hour ride from here.

Finally installed a needle valve ratchet salvaged from a Testors .35 RH parts engine, now is complete.