Anyway. I have an old Testors engine. Was trying to post a picture of it. It came off a slow combat plane I bought circa 1977. Forgot I even still had it. Looks like a 35 or 40. Uses a Super Tigre  needle assembly.  Runs great!  Just trying to figure out which one it is.  I set it aside back in the day because it was very hard to start by hand.  Very little compression unless spun faster. Electric started requires. Was told it was "reworked."  On the engine stand and just 5% nitro, sounds very strong. 

They're awesome! I love them.  Weren't so good back in the day, but now that I know what I know, I run them and fly them a lot.  Just know you're limited to around 14K-15K on a 5x3 prop.  But if you build light you'll love flying them.

That's if you're talking the Testors Fly 'Em engines, not the Wen-Mac engines.  Different beasts altogether.  But I love those too.

Mark

Ahhhh.... Those Testors engines.  The Series 21 engines ran okay, but seemed too heavy to me for what they were.  But then, what do I know.

Mark

Ahhhh.... Those Testors engines.  The Series 21 engines ran okay, but seemed too heavy to me for what they were.  But then, what do I know.

Mark

   It's become common practice to take the cylinder, piston and rod out of Series 21 engines and transplant them into lightning Bolt version of the McCoys that ar5e the same size. That way when you wear it out, just replace the dykes ring and you are back in business. You need the Series 21 cylinder because the exhaust had the bridges in it in case the ring rotates around. The cylinder drop right into the lightning Bolt cases.
   Type at you later,
   Dan McEntee

Did a bit of cleaning. A light touch with my bench grinder/wire brush revealed McCoy 35.  Just like one posted earlier except the head is plain aluminum and not black.  Is this engine very rare?  Fired up, turning a 10-6 prop and 5% nitro, I thought it was a 40.  Seems like it would be great on a Ringmaster.

   If it looks like the photo in Air Miniatry's post , with the "McCoy 35" embossed in the side of the mounting lug and the squarish main case, that is a series 21 Testors/McCoy .35. They do run pretty well, but are a bit heavy/ They are a ringed engine, with a L shaped ring at the top of the piston, so that compression tends tp help expand the ring. If yours has been sitting around, the ring may be stuck in the groove a bit. Locate a new ring to have handy, see if you can find some end gap specification for the ring gap and check that, and then you might want to take it apart to clear out the groove if you are up to it. It's not too hard, just takes a slight touch to get one side of the ring out and work it up and around the rest of the way until it's all out. Then take something sharp, and some oil, and scrape the groove all the way around, and clean it with some solvent afterwards. Clean up the cylinder, and try to put a cross hatch pattern in the cylinder walls with some 600 wet or dry paper, but don't get too aggressive. If you have a small hone with some fine stones, you can do that also but do it by hand. Clean it all up afterwards with solvent to get the metal and grit out. Replace any gaskets that may need replacing. Then replace the ring. When putting the cylinder back on, try to have the end gap on the ring in a place towards the back of the cylinder where it is smooth metal all the way from top to the bottom. Oil the cylinder walls up with some light oil and slowly work it down, and compress the ring with your fingernail or an o-ring pick. It the end gap isn't lined up correctly, make adjustments now and start over.  When you are happy, put the head and screws back in, and see how it flips over. If you changed the ring, and have the gap correct, it will take some rich runs to seat the ring, and you can tell that by how much black gunk comes out of the exhaust. USe fuel with at least half castor at at least 22 to 28% total oil. When the exhaust starts to get clear, then you are there. Usually take 4 to 6 runs and do it with a smaller diameter and flatter pitch prop than what you would fly the model with. Some don't care for the big case and that is how the trend of swapping out the cylinder parts from the 21 to the Lightning bolt started. The engine isn't rare, it's probably just had the head cleaned by some one with a wire wheel like you did to the case, it happens. If it's all you have, then just run it correctly and you will get some good life out of it. Try 10-5, 10-6, and 10.5-5 props and experiment.
   Type at you later,
   Dan McEntee

George, I'm glad your Mickey is looking promising--but I wouldn't recommend mounting the engine short on either of the planes you mention. Instead, go for a tank that you know is going to run well, and add tailweight if needed. Sure, that is practically stunt sacrilege around here. But ask yourself--do you want it to run well every time? Without all the poor runs from the wrong geometry tank?

Suggest you stick to the standard wedge style that is 1" tall and 2" wide. Deeper, fatter tanks used on short noses to get the required fuel load often won't run right, or are finicky. A Mickey is not going to tolerate a lot of missed needles and bad tank runs. Pressure helps, but can't fix draw problems when the tank is just too fat....

Good luck with your plane, whatever you decide to do,

Dave

AirMiniseries,

That's a lot of spiffy Spit tankage. But the secret is right there on yer picture--the electric fuel pump and the aneroid dohickey. Musta been a page out of a late model manual after they fixed the inverted fuel flow problems...?

As far as the model profile tank, I dunno about the double bevel "large profile tank," which is what Brodak calls 'em. The narrower width is nice, so that the venturi doesn't have to draw too hard against the normal 3-G radial acceleration, but the height has got bigness, so you are depending on the 3-G force to keep the outboard bevel full of fuel. That doesn't look like a great approach if you are turning hard and exceeding 3-G vertical loading with a near-empty tank. That said, I've only seen one of these double bevel jobs at the field in the last 15 years, and that was just recently. I'll be watching with interest to see if the guy can do hard maneuvers near the end of the tank or if the engine coughs and sputters....

The Divot

For what it's worth, for some reason, I can't post pictures on facebook anymore. Must be my computer.  But the McCoy 40 is just like my 35.  C/L - not R/C

    Yes, they look exactly alike, and you have to look at the embossing on the engine mount side. Same engine for either R/C or C/L, except that the C/L engine had the formed velocity stack. The R/C engine can have the carb removed and an after market venturi installed with needle valve also. They are not a terrible engine, just not the top of the mark. That's why I built up a few .40's with the series 21 guts in them, to look more classic and I think they are a bit lighter.
   Type at you later,
    Dan McEntee