News:



  • March 28, 2024, 03:45:31 PM

Login with username, password and session length

Author Topic: A SIMPLE WAY TO INCREASE PERFORMANCE OF AN O.K. .049  (Read 2219 times)

Offline Robert Zambelli

  • 23 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2913
A SIMPLE WAY TO INCREASE PERFORMANCE OF AN O.K. .049
« on: September 12, 2018, 07:43:14 AM »

(Assuming you are starting with a good, tight engine)
PHILOSOPHY: Minimize internal friction and impedance to fuel flow – no timing changes.

Carefully disassemble the engine and place the parts in a jar.
Pour in equal parts of lacquer thinner and methyl alcohol to just cover the parts.
Loosely seal the jar and place in a pan full of hot tap water for about 15 minute, swirling it gently a few times.
Remove the parts and blow them dry with compressed air. Examine everything to insure that it’s meticulously clean. Remove any signs of rust, especially in the cylinder. Fine Scotchbrite works well.

With a Dremel and the smallest bits and stones you have, carefully break any sharp edges in the fuel path.
Crankshaft – the rear inner edge of the intake port usually has a burr – round it slightly. Where the inside bore meets the crank flange, remove the sharp edge and flare the hole. Smooth off all the sharp edges on the crank flange and counterbalance.  With a soft cloth, polishing compound and crocus cloth, gently polish the inside bore, main bearing and crank pin. I’ve heard of drilling a hole in the crank pin but I have not tried it.
Connecting Rod – Remove all casting marks and edges. Polish the rod to a high luster. If you have a # 75  80 drill, drill an oil hole at the lower side of the lower end. Deburr the hole.
Case – smooth off any sharp edges on the inside. Flare the top of the vertical by-pass ports. Polish the inside.
Wrist pin – polish the ends and running surface like a mirror.
Piston – Relieve it. Decrease the diameter below the wrist-pin hole by about .0005”. You can verify the clearance by gently placing the dry piston skirt-down in the top of the dry cylinder. Turn the cylinder upside down and the piston will fall out.
Cylinder – there are three by-pass ports. VERY carefully remove any burrs at the lower opening and flare them very slightly. Don’t touch the bore side of these ports.
Backplate – polish the front face.
Head – needs nothing.

Blow off all the parts with compressed air and insure that there are no chips or polishing compound anywhere. Put a drop of oil on the wrist pin, crankpin and crankshaft main bearing. Carefully reassemble without gaskets on the lower cylinder or backplate. If you suspect leakage, put a tiny, thin film of RTV on the surfaces.

Before installing the head, put a few drops of oil in the intake and in the bore, then turn the engine a few turns. It must turn smooth-as-silk. Install the head. If you feel ANY interference at TDC, add the needed number of head shims.

That’s al I do. I do nothing to the NVA except a meticulous cleaning.

HAVE FUN!!!

Offline Bob Matiska

  • 2020 supporter
  • Trade Count: (0)
  • Lieutenant
  • *
  • Posts: 92
Re: A SIMPLE WAY TO INCREASE PERFORMANCE OF AN O.K. .049
« Reply #1 on: September 12, 2018, 02:43:50 PM »
Thanks, Bob. I have 2 Cub 049s I acquired many years ago from the factory that are still in the box. I WILL mount them on a couple of Black Hawk models, when I build those!  Probably wouldn't hurt to go over them first.

BTW, my first engine was a Cub 049, the one with the integral red tank. My cousin gave it to me as a favor, but it was pretty well worn out even then. I learned a lot about starting glow motors from that thing! Especially patience!

Bob in NEPA
AMA 56267

Online kenneth cook

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1464
Re: A SIMPLE WAY TO INCREASE PERFORMANCE OF AN O.K. .049
« Reply #2 on: September 13, 2018, 06:34:55 PM »
          Can the spraybar be flipped around? Ken

Online Brad LaPointe

  • 24 supporter
  • Trade Count: (0)
  • Commander
  • *
  • Posts: 331
Re: A SIMPLE WAY TO INCREASE PERFORMANCE OF AN O.K. .049
« Reply #3 on: September 14, 2018, 05:57:58 AM »
Nitro baby , nitro !!! The crank will break long before you max out in the race for performance.

Brad

Offline Robert Zambelli

  • 23 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2913
Re: A SIMPLE WAY TO INCREASE PERFORMANCE OF AN O.K. .049
« Reply #4 on: September 14, 2018, 08:15:51 AM »
          Can the spraybar be flipped around? Ken

Yes - the spaybar has a fine knurl yielding a light press fit.
You can tap it out and reverse it with no problems.

Bob Z.

Offline Dave Hull

  • 24 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1901
Re: A SIMPLE WAY TO INCREASE PERFORMANCE OF AN O.K. .049
« Reply #5 on: September 14, 2018, 11:31:16 AM »
Bobzam,

Did you do a before and after comparison? How much improvement did you get? What prop and rpm?

Curious Cox Addict

Offline dennis lipsett

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1719
Re: A SIMPLE WAY TO INCREASE PERFORMANCE OF AN O.K. .049
« Reply #6 on: September 14, 2018, 02:10:04 PM »
The 1966 OK cub 049 and 061 were probably their best. The single most notable improvement was a real glow head. Alas it was too little too late.

Online Brett Buck

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 13717

Offline Steve Helmick

  • AMA Member and supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 9920
Re: An even simpler way TO INCREASE PERFORMANCE OF AN O.K. .049
« Reply #8 on: September 15, 2018, 06:06:55 PM »
https://img0.etsystatic.com/038/0/9074196/il_570xN.619275866_5na0.jpg


Beat me to it, Brett! The sure way to cure the "high performance" of my first CL model was to install a Cub .049. It would barely stagger into the air with the Cub, so I knew I'd better not over-control it. Later the Cox Babe Bee returned to the firewall, when I sorta had the hang of this CL thing. That Francisco "Blue Blazer" was the bee's knees, huh?   LL~ Steve
"The United States has become a place where professional athletes and entertainers are mistaken for people of importance." - Robert Heinlein

In 1944 18-20 year old's stormed beaches, and parachuted behind enemy lines to almost certain death.  In 2015 18-20 year old's need safe zones so people don't hurt their feelings.

Offline Bill Adair

  • 21 supporter
  • Trade Count: (0)
  • Captain
  • *
  • Posts: 882
  • AMA 182626
Re: A SIMPLE WAY TO INCREASE PERFORMANCE OF AN O.K. .049
« Reply #9 on: September 15, 2018, 09:07:32 PM »
My Firebaby would not get off the ground, with a Cub .049 installed. Field was a back yard, mowed with the high tech push type reel mower of the day.

Fixed by removal of the Cub, and installation of a new McCoy .049 Diesel, using hand mixed Olde English diesel fuel (equal parts of drug store Castor oil, Kerosene (from our kitchen stove storage tank), and drug store Ether (no Cetane booster at all).

The Cub drug it around until it nosed over in the grass which was every attempted takeoff, but the McCoy yanked it off the ground like it was rocket assisted!  ;D

Bill
Not a flyer (age related), but still love the hobby!

Offline Robert Zambelli

  • 23 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2913
Re: A SIMPLE WAY TO INCREASE PERFORMANCE OF AN O.K. .049
« Reply #10 on: September 18, 2018, 03:02:49 PM »
Bobzam,

Did you do a before and after comparison? How much improvement did you get? What prop and rpm?

Curious Cox Addict

Yes, Dave - I did a comparison.
When I first started with the Cubs, I found that they liked lots of nitro and small props -  30% nitro, 5 1/2-4 Top Flite wood was the ticket.
Even then, they were marginal on power so I started experimenting.
With the modifications I performed, the engine turned a 6-4 Top Flite wood almost 2,000 RPM faster than the stock engine turned the 5 1/2-4. Unfortunately, I can't remember the exact RPM when stock but it was around 13,000 as I recall.
Another big plus - the higher compression made them much easier to start.

The 6-4 prop made an incredible improvement in the performance of the various planes I tried it on.

Back when the NVCL club had the Musciano commemorative "Hollow Log" event, my planes, powered by Fox 049s and my modified Cubs allowed me to bring home many trophies.

I have nothing against Cox engines and know very little about them but I just wanted to see how much I could get out of an OK Cub. Some people laughed when I brought them to the contest but seemed to stop laughing when the winners were announced.
I guess a bit of hard work and perseverance pays off.

Bob Z.





Offline Dave Hull

  • 24 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1901
Re: A SIMPLE WAY TO INCREASE PERFORMANCE OF AN O.K. .049
« Reply #11 on: September 18, 2018, 07:00:41 PM »
Thanks for the added info, Bob.  Are they fragile after the power is increased or do they hold up well?

One of our long-time modelers here built a plane around a Cub recently. He said they were a "one speed" engine. And that you didn't know what the speed of any particular Cub would be until you tried it. With your cleanup, it seems like they would overcome these setup issues....

I had my hands on a few used samples, but after I cleaned them up, the guy wanted them back. So I never got a chance to run them to see how they would go. I couldn't baseline those, because they were not runnable as received.

Dave

Offline Chris Sarnowski

  • Trade Count: (0)
  • Ensign
  • **
  • Posts: 48
Re: A SIMPLE WAY TO INCREASE PERFORMANCE OF AN O.K. .049
« Reply #12 on: September 21, 2018, 10:06:27 AM »
Maybe we should have an Ok Cub 049 / AJ Firebaby postal speed contest.

Offline Chris Sarnowski

  • Trade Count: (0)
  • Ensign
  • **
  • Posts: 48
Re: A SIMPLE WAY TO INCREASE PERFORMANCE OF AN O.K. .049
« Reply #13 on: September 22, 2018, 07:53:14 AM »
Here’s a photo of the needle taper on an early cub that I grabbed off eBay.

Offline Larry Renger

  • 21 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 3995
Re: A SIMPLE WAY TO INCREASE PERFORMANCE OF AN O.K. .049
« Reply #14 on: September 22, 2018, 08:08:55 AM »
I prefer replacing the spraybar and needle with the one from a Cox rtf engine.
Think S.M.A.L.L. y'all and, it's all good, CL, FF and RC!

DesignMan
 BTW, Dracula Sucks!  A closed mouth gathers no feet!

Offline GallopingGhostler

  • 23 supporter
  • Trade Count: (0)
  • Captain
  • *
  • Posts: 510
Re: A SIMPLE WAY TO INCREASE PERFORMANCE OF AN O.K. .049
« Reply #15 on: September 25, 2018, 04:42:12 AM »
I prefer replacing the spraybar and needle with the one from a Cox rtf engine.
I think you may be on to something, Larry. The OK needle has a split sleeve that goes over the needle threaded area. I find that the needle threaded area leaks making adjusting during a run twitchy. I've removed the spring and put a section of silicon fuel line over this, but it is difficult to get a good seal with the fuel line with the slits in the collar, although it improves it somewhat.

Using the Cox spray bar and needle would allow a better seal and more consistent running.

Online Ken Culbertson

  • 24 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 6036
Re: A SIMPLE WAY TO INCREASE PERFORMANCE OF AN O.K. .049
« Reply #16 on: September 25, 2018, 08:05:21 AM »
Maybe it is just bitter experience as a kid but IMHO the best thing you can do with an OK Cub .049 is encase it in clear plastic and use it as a paperweight.
AMA 15382
If it is not broke you are not trying hard enough.
USAF 1968-1974 TAC

Online Dan Berry

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1054
Re: A SIMPLE WAY TO INCREASE PERFORMANCE OF AN O.K. .049
« Reply #17 on: September 25, 2018, 08:46:25 AM »
It is possible to set up an OK Cub 049 so that it will turn an APC 6x2 20,000 rpm.
It's still touchy on the needle and won't last real long.
Mr Cox made a lot of money off of Cub sales...…….

Offline GallopingGhostler

  • 23 supporter
  • Trade Count: (0)
  • Captain
  • *
  • Posts: 510
Re: A SIMPLE WAY TO INCREASE PERFORMANCE OF AN O.K. .049
« Reply #18 on: September 25, 2018, 08:56:58 AM »
Maybe it is just bitter experience as a kid but IMHO the best thing you can do with an OK Cub .049 is encase it in clear plastic and use it as a paperweight.
Should there be an OK Cub .049 Hurl Contest like with the Fox .15's?  %^@  VD~  S?P  LL~

It is possible to set up an OK Cub 049 so that it will turn an APC 6x2 20,000 rpm. It's still touchy on the needle and won't last real long. Mr Cox made a lot of money off of Cub sales...…….
OK Cub prop of choice seemed to be a 5x3. Weakness was lower compression from the glow plug head. I heard there was also a glow head later on that increased compression similar to the Coxes and provided a better run. I don't know about getting 20,000 rpm though, may be on high nitro racing fuel?

I also have the later OK .06 Cub C reed valve with tank. It was a nice NOS gift from a friend. Have yet to run it, but heard they were a decent engine, about equivalent to a Cox .049 Babe Bee.

Online Ken Culbertson

  • 24 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 6036
Re: A SIMPLE WAY TO INCREASE PERFORMANCE OF AN O.K. .049
« Reply #19 on: September 25, 2018, 01:45:56 PM »
Should there be an OK Cub .049 Hurl Contest like with the Fox .15's?
Could be the same event but you are going to get better distance with the FOX.

The Fox 15 has a special place in my memories though.  It was my first engine that looked like an engine and it powered my Flight Streak Jr. into the ground numerous times as I learned to fly with the tail pointed down.  It was hard to start but at 12 you really didn't know that was because it was a sucky engine.  Fortunately I lost it on a FF and replaced it with a Fox 35 for my freshly completed Nobler.

Ken
AMA 15382
If it is not broke you are not trying hard enough.
USAF 1968-1974 TAC

Offline Bill Adair

  • 21 supporter
  • Trade Count: (0)
  • Captain
  • *
  • Posts: 882
  • AMA 182626
Re: A SIMPLE WAY TO INCREASE PERFORMANCE OF AN O.K. .049
« Reply #20 on: September 25, 2018, 01:57:15 PM »
Never owned a reed valve Cub engine, but picked up a few of the later OK .049 glow head cylinders.

Too little too late for OK, as those cylinders were the same thread as Cox glow heads, and a Cox Tee Dee head would probably boost performance even farther. If you really wanted to stress a Cub .049, you could fit a Galbreath head and Nelson plug for what would probably be a very brief burst of power.  ;D

Bill
Not a flyer (age related), but still love the hobby!

Offline EddyR

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 2562
Re: A SIMPLE WAY TO INCREASE PERFORMANCE OF AN O.K. .049
« Reply #21 on: September 25, 2018, 03:38:35 PM »
I used the Cub .14 and .19 in my early RC model a DeBolt 1957 Live wire trainer. !0/3 prop pulled it just fast enough so I could control it on escapement rudder only.
Tube Deltron receiver. Hal DeBolt took pity on me and gave me his Trainer that he built for the photos that went on the box. I later put a reed set up in it.
Ed
Locust NC 40 miles from the Huntersville field


Advertise Here
Tags:
 


Advertise Here