1960's Testors McCoy .35 Black Head

[George Hostler]

Is this normal for a Testors McCoy .35 Red Head?  Engine still runs strong with excellent compression, but the Red head turned into a Black head. I'm using 25% oil and 15% nitro (at 4,300 feet elevation). Went into a strong 2 cycle but didn't seem out of the ordinary. This is after about a half dozen flights. Last flight did a nice 4-2-4 break. This engine does really long flights on only 3 ounces of fuel. 



Paint appeared to be OEM, but doesn't appear to be heat resistant. I'm thinking about stripping it and using Duplicolor spray Ceramic High Heat Black Engine Paint and paint it black, to match my Ringmaster S-1, LOL. 

Anyway, being new to the McCoy, I really like how easy starting this engine is, how smooth it runs, really pulls the S-1 on 60 feet lines with authority. Would like to have some inputs from those more familiar, as I have a half dozen of these Testors jewels in my possession I plan to put to use. 

[Dave_Trible]

I have some experience with your motor.  Black is real bad!  A few more runs like that and it's junk.  At least 28% oil and and easy 2-4 break is how you must run it.

Dave

[George]

If you are not running it too lean, there is the possibility that it was repainted with the correct color but not high-temperature paint.

I understand that the reason they require more than average lube is because of the metallurgy used in the piston.

George

[Paul Taylor]

There is a product called Demon clean that will take that off. Also if you can find Dawn Power devolve for cleaning pot and pans.
As others said dont run them lean and use 28-29% castor.
They are a OK motor if cared for.

[Jim Kraft]

The only way to clean McCoy heads is in the crockpot, but that will remove paint and all down to bare metal. I have repainted them with the ceramic high heat engine paint, but the problem is that it resists heat very well but not hot fuel. It will begin to bubble up over maybe 20 or 30 flights and begin to peal off. I have found that just regular enamel works as well as anything to repaint them. And yes, 28% oil preferably mostly castor works the best, and even then resist lean runs. They do loose compression much quicker than other engines on the count of the sintered iron pistons, but as long as they have enough compression to start they still seem to run the same as they do when are fairly tight. I have seen some that had so little compression that they would not start until castor was squirted into the exhaust port to start. Then they still run with as much power as they do otherwise.

They are reparable by tapping the dome of the piston with a hammer to spread the top of the piston. Just don't tap to hard or you will have a broken piston. I have done this 4 and 5 times to the same engine to restore compression. Sounds crude, but it works. Otherwise you just have a useless engine anyway.

[dennis lipsett]

The only way to clean McCoy heads is in the crockpot, but that will remove paint and all down to bare metal. I have repainted them with the ceramic high heat engine paint, but the problem is that it resists heat very well but not hot fuel. It will begin to bubble up over maybe 20 or 30 flights and begin to peal off. I have found that just regular enamel works as well as anything to repaint them. And yes, 28% oil preferably mostly castor works the best, and even then resist lean runs. They do loose compression much quicker than other engines on the count of the sintered iron pistons, but as long as they have enough compression to start they still seem to run the same as they do when are fairly tight. I have seen some that had so little compression that they would not start until castor was squirted into the exhaust port to start. Then they still run with as much power as they do otherwise.

They are reparable by tapping the dome of the piston with a hammer to spread the top of the piston. Just don't tap to hard or you will have a broken piston. I have done this 4 and 5 times to the same engine to restore compression. Sounds crude, but it works. Otherwise you just have a useless engine anyway.

Starting back with the worthless McCoy 098 I used to do this to most of the wore out McCoy's that passed through my hands as a kid. I would prime with 70 weight oil then a prime of fuel, hook up the battery and hit the prop like I really meant it and then when the engine stopped it would on occasion free wheel down to the ground to have the process repeated ad infinitum.
Most McCoy's didn't know they were wore out with that treatment.

[Jim Kraft]

The McCoy Red Heads defy the idea that the piston cylinder fits have to be great to run right with power. They can be as loose as can be, but if you can get them started they run as well as if they were fit to a tea. Can anyone explain this? Maybe it is the high castor fuel we feed them. Other engines start loosing power when they start leaking down a little.

[Avaiojet]

Many ebay sellers repaint the head and polish the brass. Looks is everything.

Gotta be careful with ebay.

[George Hostler]

Thanks, all for the replies, they are good inputs.

Jim, thanks for the comment on Duplicolor High Heat not being fuel resistant. You spared me an attempt that would not have succeeded.

I heard that regular Duplicolor engine paint works, preferably Ford Red, which is close enough to McCoy OEM. That it might be aftermarket paint applied to the original paint, I noticed some flaking off as a thin black coat. I pulled this head off another engine I had, since one I was using was leaking plus borrowed the socket head screws off it. It very well could be touched up. I have Plasti-Kote engine paint, it too is not as good as Duplicolor regular engine paint? Rather than paint, I guess I could simply leave it in the bare aluminum like the Foxes and other engines.

Regarding loose piston fit will still run well. I noticed the same on one other McCoy 35 RH, too. I had a similar experience with one plain bearing Enya .15-III that was worn out, most likely abused. If I could get it to tick over, it seemed to run as strong as one with a good piston fit. Perhaps it is related to both Testors and Enya being cross scavenged and the engine Castor oil content is sufficient enough to maintain the seal during run time?

I've heard about the crockpot treatment but never tried it. I have an old electric Polyperk percolator with a slow leak, not good for much else, thought I might try it with engine. Once it stops boiling, it rolls over to heating mode.

[phil c]

The McCoy Red Heads defy the idea that the piston cylinder fits have to be great to run right with power. They can be as loose as can be, but if you can get them started they run as well as if they were fit to a tea. Can anyone explain this? Maybe it is the high castor fuel we feed them. Other engines start loosing power when they start leaking down a little.

I had an LA 25 that just kept running better and better.  Then it got hard to start, but ran even better.  Finally I couldn't flip it fast enough to get it started and bought a new piston/liner.  Back to it's original slow self.

Phil C