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Engine basics => Engine set up tips => Topic started by: Dick Pacini on October 13, 2009, 08:37:32 PM
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Has anyone ever run a McCoy 40 Series 21 with success? I have located a couple of new ones and am wondering if it would be a good match for an Ultra Hobby Gieseke Nobler.
I remember the old Red Head 40s were pretty decent, but don't remember much about the Series 21.
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The 21's got a bum rap because they were about 1oz. heavier than some of the competition. All three, the 19, 35, and 40 run well, but I'm not sure how well the 40 does a stunt run. It has the same bore and stroke as the Lighting Bolt 40, so it should be close.
The Geiseke Nobler was designed around a Fox 35, which weigh about 2 oz. less than the Series 21 40. You'd have to take that into account if you don't want to add another ounce with tail weight. Maybe shorten the nose half an inch, push the stab back half an inch, use a heavier, carbon fiber pushrod.
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I understand the hot setup is to pull the guts out of the '21's and put them in an old standard wore out engine case. Best of both....
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I flew three different McCoy Ser. 21 40's in a Viking. The best one would fly it OK. No comparison with the K&B 4011 which replaced them. I have no need of a McCoy series 21 engine.
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The Testors McCoy Series 21 engines have Dykes piston rings which expand under compression when running. If the crankshaft is turned slowly by hand, very little compression is felt. Some mistake this lack of compression as an indication of a worn or malfunctioning engine. Also, the Series 21 engines perform much better with fuel containing about 25% castor oil.
These engines are heavy but for sport flying in appropriate planes, they do well.
Joe
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The Testors McCoy Series 21 engines have Dykes piston rings which expand under compression when running. If the crankshaft is turned slowly by hand, very little compression is felt. Some mistake this lack of compression as an indication of a worn or malfunctioning engine. Also, the Series 21 engines perform much better with fuel containing about 25% castor oil.
These engines are heavy but for sport flying in appropriate planes, they do well.
Joe
I'd like some to define "heavy". The LA 40 nan 46 are close to thr same weight at the 21, so is the EVO 36 and folks rarely say they are heavy.
Bob's idea of putting a series 21 piston and liner into an older, lighter case is a good one if you have the equipment. Less vibration and a replaceable ring.
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I ran a Series 21 40 for about 3 years (quite awhile ago now). They have a very nice stunt run with adequate oil, but are not very powerful. No comparison to modern 40s. Not much more (if any more) power than a Fox 35.
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Tom Lay is the man When it comes to old McCoy's He has been reworking then since they were new. He heats treats the parts and hand laps them to fit. His engines have terrific compression and last longer that the originals. He built one for Larry Brickaman back in the day that ran so slow they were a sight to see. He dose OS 35 the same way . one flip starts . Get all you can he is the man !
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The Series 21 sleeve/piston assemblies will drop right into the matching Red Head cases EXCEPT for the .40. I have a .29 *hybrid* which runs better that way than the Red Heads (stock) that I have. If I can find a Series 21 .35 I will convert one of those. With a replaceable Dyke's Ring, it gives you some latitude on running the old Red Heads.
The OD of the Series 21 .40 jug is larger than the case opening on the .40 Red Head. You can machine the RH case if you have the equipment............
Doesn't Jim Kraft (can't remember exactly who it is) run some shaved down case Series 21 .40s??
Mongo
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I just swap out the piston/rod from a series 21 to the Lightning bolt 40. You also have to use the series 21 head as the piston pin hole is closer to the crown than the original. I think I had to jigger the holes a bit in the head to get a line up. Runs great, much like the original.
Al Burczycki
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Hi guys,
In the early 70's I abandoned the fox 35 for 2 of the series 21 McCoys and they gave great runs. I later I bought 2 more series 21 McCoys and they ran poorly. I called the factory in California and chief engine production man Bill Netzeband answered my call. Bill imformed me that thay had gotten a bad shipment of rings that were producing bad motor runs, but unfortunately, I was a beginning stunt guy, so I was just never again able to get my McCoys to give me those great runs.
I moved on to the "series 70" K&B 40 and never looked back.
I am sometimes tempted to buy some new sleeves for my remaining series 21 engines from Mecoa and send the engine to Mr Bowman to provide a properly fitted ring, just to test if my memory about the quality of the series 21 motor run was close to my current perceptions.
Pat Robinson
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The persistant myth that these are heavy is only true when compared to the engines of the same era, i.e.- the Redhead's it replaced. I have a 5 of the .35 C/L versions and 1 carb'd. I always thought they were good looking and unique. Pretty durable too...I augered in a Banshee 4"+ deep in dirt and the only damage was the prop and NVA. The Sig was toast n~.
From what I've read they were developed for Combat. Pretty powerful for a baffled engine when run in 2-stroke.
The .40 was supposed to be the best of the bunch for Stunt.
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Hey Mongo; I do run a couple of Red Head 40's, but they are both stock. I have often thought of getting a series 21 off the bay to either run or refubish an old Red Head, but so far have resisted. " My wife says I'm a ebay junkie. " I do have to redo the piston cyl. fit on the old Red Heads every couple of years, but they do run great. Best running profile engine I have found.