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Author Topic: How to massage a Redhead?  (Read 710 times)

Offline wwwarbird

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How to massage a Redhead?
« on: September 06, 2010, 07:26:48 PM »
 First, sorry to disappoint anyone, but please make sure that you are on the correct forum. ;D :##

 Seriously, I've just taken possession of a slightly used McCoy .35 Redhead that I plan to use for an upcoming (next) project. It seems to have very little time on it and I want to optimize my use of it, and it's life. I haven't personally setup and run any Mccoys before. I'm intending to use it on a "Super Combat Streak" that I just purchased from Walter Umland.

 Without getting overly elaborate, I'd like to hear some general suggestions on running and setup combos and minor mods that would prolong engine life and performance. One mod I've heard of is to drill a small lubricating hole in the rod end at the crank. If done, common sense would dictate angling that hole slightly to "scoop" lubrication toward the crank lug while the engine is running. Any suggestions on this, or any other mods or setup combos will be appreciated.

 Thanks! H^^
Narrowly averting disaster since 1964! 

Wayne Willey
Albert Lea, MN U.S.A. IC C/L Aircraft Modeler, Ex AMA member

Offline Jim Kraft

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Re: How to massage a Redhead?
« Reply #1 on: September 06, 2010, 08:50:40 PM »
If I were to drill a hole in the rod, that is the way I would do it. I have been running 3 or 4 McCoy 35's for the last 10 years or so, and I just run lots of oil, mostly. 25 to 29% castor, 5 or 10% nitro. I have not had any of mine wear the rod on either end, and all of mine have little to no wear in the shaft brg. After a couple of years of hard running, or a really lean run, I expand the top of the piston by tapping on it with a small hammer to get the compression back. They really are a nice running motor for stunt. I use 10-6 APC props most of the time, but they will also run nice on 10-5's and 11-4's. They work well on either uniflow or standard vent, depending on what works best on the particular plane you have it on. I run Thunderbolt idle bar plugs.
Jim Kraft

Offline wwwarbird

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Re: How to massage a Redhead?
« Reply #2 on: September 07, 2010, 12:55:47 AM »
 Thanks Jim. I did plan on running 10% with at least 20-25 percent all castor, maybe I'll add a little more even. I don't really anticipate having to do it, but just in case, exactly where and how do you go about tapping on the piston with a hammer? I can't say I've ever heard of that one.
Narrowly averting disaster since 1964! 

Wayne Willey
Albert Lea, MN U.S.A. IC C/L Aircraft Modeler, Ex AMA member

Offline Bill Little

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Re: How to massage a Redhead?
« Reply #3 on: September 07, 2010, 06:58:34 AM »
Hi Wayne,

Like Jim said, there isn't much (if anything) that needs to be done to a McCoy Red Head for stunt.  The major problem was the very soft piston, and crank bearing.  Those would wear out quickly if you were not careful.  I have seen them go south with one over lean run on low castor oil fuel.

I am pretty sure Jim is tapping on the top (crown) of the piston to slightly deform it in diameter.  If you happen to have a Testors Series 21 .35 (way to heavy an engine! LOL!!) you can swap the pistons.  The Series 21 had a dykes ring.  This also works on the .40s. 

The Series 21 sleeves will also swap on the .29 and .35, but the .40 needs the case machined.

Big Bear
Big Bear <><

Aberdeen, NC

James Hylton Motorsports/NASCAR/ARCA

AMA 95351 (got one of my old numbers back! ;D )

Trying to get by

Offline Jim Kraft

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Re: How to massage a Redhead?
« Reply #4 on: September 07, 2010, 07:06:57 AM »
The safest way is to remove the piston and cyl. and set them on an anvil with the piston right side up in the bottom of the cyl.. Then take a wide (1/4") punch, and using a small hammer, lightly tap the dome of the piston right in the middle. It will spread the top of the piston enough to get good compression again. I sometimes take the piston out and mic it, then just set the piston alone on the anvil, and tap it a few times with the hammer. I then mic it again, and I do this until it has grown about .001" to .0015". If you go to far you will have to lap it back in again. The pistons are sintered iron, and can be broken if you are not careful. It just takes light taps with the hammer. I have done this to all of my McCoy 35's at least once, and to my 40's, 3 or 4 times. Travel at your own risk.
Jim Kraft

Offline Russell Shaffer

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Re: How to massage a Redhead?
« Reply #5 on: September 07, 2010, 09:08:42 AM »
Has anyone tried to case harden one of these pistons?  It would be easy with Casenite (sp). 
Russell Shaffer
Klamath Falls, Oregon
Just North of the California border

Online kenneth cook

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Re: How to massage a Redhead?
« Reply #6 on: September 07, 2010, 06:32:19 PM »
        In the event you need to take the cylinder off, I found a way that has worked well for me. I apply 3n1 oil liberally at the bottom of the cylinder where it meets the case. I then let it soak for about an hour checking to see that it runs all the way around. I then take the heat gun and heat the cylinder and case connection while holding it with a glove. I do this until it smokes . I then place it in the vise and give the cylinder a bit of a twist not pulling until it breaks free. The cylinder then comes out without damaging the gasket. I've done this several times with good success. The heat gun I use is the type for paint stripping so it does get very hot. Just thought I'd mention this if it wasn't already known. The one problem I run into with these engines is not only the disintegrating piston but the wrist pin holes look like ovals. I'm not quite equipped to fix that problem. Ken


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