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Post  Ken Cook on Tue Jan 01, 2013 8:42 pm

I had the pleasure of heading out to the field this afternoon. It was COLD!!!!!. Nonetheless, several of us made it out for some 1/2A of all things and some Ringmaster and Bislob fun. A recent flyer who purchased one of the Brodak MK II engines was having a difficult time getting there new engine running. This little engine didn't impress me initially until closer inspection. This engine is a AAC construction with some pretty impressive fits. I wasn't very satisfied with the MK 1 CS version engines but I eventually managed to get some good rpm's out of it. As I stated, the fits were quite good, and a really well built engine.

The engine was completely taken apart, cleaned and reassembled. Inital test run wasn't overly promising on a Cox gray 5x3 which yielded a top rpm of 14k. Not happy with those results, a closer look was taken at the crank to case fit. I prefer the crank to really WHIZZ!!!!! when you spin it. Any tight or roughness is going to quickly rob rpm's. I spent a good bit of time polishing the crank and I also chamfered the case where the crank web rests up against on the inside. All parts cleaned again and out for testing again. I just didn't expect the results I was seeing. I knew that I was going to see an increase, but I liked the results I was seeing now. Fuel was Sig 35% and I switched to the APC 5x3. I'm not a fan of the standard glow plug in this engine and have some ideas for head replacement. I certainly feel there is some real potential hidden in this engine. I just believe the engine is mildly timed and was probably designed more around a beginner style run. I just feel with some hopping up and maybe even some crank changes, this little mill could certainly see some high numbers. I eventually hit 22k today after some run in time. Ken Brodak MK II Dscn1619


Last edited by Ken Cook on Tue Jan 01, 2013 9:23 pm; edited 1 time in total
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Post  Cribbs74 on Tue Jan 01, 2013 8:45 pm

Good work Ken,

You got that thing turning pretty quick! Is the crank all you massaged?
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Post  Ken Cook on Tue Jan 01, 2013 9:09 pm

Yes, the engine was not really flipping over with momentum if that makes sense. I dressed the front of the case as well removing the faint mold line in the casting. I don't like it when the thrust washer has any drag on it either. Why introduce yet another friction point. This engine isn't mine but I feel that I could achieve more rpm's from it. The bottom line is that this engine would have taken quite some time to break in. I loosen my crank fits in the case itself in my Norvel's and I was going to do this on this particular engine. I have a friend who does this for me on a hone machine. Seeing that this isn't mine, I left it alone. When I do this at home, I'm using grits and polishes. These can be difficult to remove from aluminum. Most 1/2A engines have the steel crank running in a aluminum case. The only 1/2A engine that uses a bronze bushing that I'm aware of is the AP Wasp .061.

Removing the grit residue is difficult which I use a nylon bristle brush and pipe cleaner like gadgets in hot soapy water. I follow that up with a sonic cleaner. As I mentioned, I'm not a fan of the standard glow plug as I know volume is being lost in the threads and also the internal cavity of the plug itself. I certainly feel that making a new head and using a turbo plug for instance would result in some higher rpm's. As it stands in stock form however, the rpm's I'm seeing make it a viable power plant.

I forgot the best part, the Bislob. Shawn was ringing in the New Year today
Brodak MK II Dscn1620
Brodak MK II Dscn1621
Brodak MK II Dscn1622
Happy New Year Ken


Last edited by Ken Cook on Tue Jan 01, 2013 9:19 pm; edited 2 times in total
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Post  duke.johnson on Tue Jan 01, 2013 9:11 pm

I have one of these still new in the box. I haven't figured out what to build for it. Huh...
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Post  Cribbs74 on Tue Jan 01, 2013 9:29 pm

Looks like fun Ken, no snow on the field yet.......yet.
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Post  andrew on Tue Jan 01, 2013 9:46 pm

Ken Cook wrote: ........ As I stated, the fits were quite good, and I found them to be too tight in some areas ............ I prefer the crank to really WHIZZ!!!!! when you spin it. Any tight or roughness is going to quickly rob rpm's. I spent a good bit of time polishing the crank and I also chamfered the case where the crank web rests up against on the inside.

The MK II is a significantly better manufactured engine than the MK I and represents eastern European technology and QC vs. Chinese technology.

The two areas you worked on are often overlooked in searching for improved performance. Some NORVELs also benefit from crank polishing and in some cases, releaving a portion of the crank journal. I think some runs may be mis-diagnosed as lean runs when, in fact, the journal/case fit tightens up as the engine heats up. The engine slows, stops and has an extremely hot case. The thrust bearing area is seldom mentioned when tuning up an engine, possibly because most speed demons are bearing instead of bushed. If I have a case that does not seem to have even wear around this bearing area or is not bright, I use a little white polishing compound and spin the crank with enough pressure to buff this area out to a uniform wear pattern.

Boosting RPM 50% is pretty danged impressive. The MK II has a reputation of being a good utility engine and well built, but not a speedster. You done good, Ken.

Here's a pic of the bones:

Brodak MK II Brodak11
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Post  duke.johnson on Tue Jan 01, 2013 9:55 pm

So after I break in the engine I have, what should I do to it?
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Post  Ken Cook on Tue Jan 01, 2013 9:59 pm

Duke, get it on the nose of a plane and fly it. I was thinking on something like a 1/2A Nobler profile. There are certainly a lot of possible options. I just have a few I would like to build. I believe the Baby Clown Arf that is currently set up for beam mounts as opposed to the earlier model which used the nylon mount would also be a good choice. I think I will look deeper into using this engine. I thought it was quite cool and certainly one that I would like to own myself. Although I don't consider myself a collector, these little engines just fascinate me. Great job showing the exploded view Andrew. It certainly does the engine justice. Ken
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Post  fredvon4 on Wed Jan 02, 2013 9:00 am

Good information here

If a fellow wanted a non Cox .049 would he choose this Brodak MK11 at $70 over either of the Norvel .049s at $55, or a FORA .8cc at $159?

Cool, unique, different not being considerations...simply bang for the buck in a easy to operate, service, and reliability for typical 1/2a combat or stunt aircraft

The frugal side of me is leaning to the Norvel short nose version

I understand the logic of the FORA, CYCLON, PROFI and Galbreth's P-zero .050 for all out competition
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Post  John Goddard on Wed Jan 02, 2013 9:15 am

Although I've only started my Norvel 061's and they are the
R/C versions Fred, they are (whisper it) more user friendly
Than another make we all enjoy...
Very powerful too.
Very Happy
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Post  Surfer_kris on Wed Jan 02, 2013 9:20 am

I agree that the crank to case fit is very important, but I can't see how the Brodak MkII would ever make +20krpm on a 5x3. What prop was used to get 22krpm?
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Post  andrew on Wed Jan 02, 2013 1:23 pm

Here's one more pic you all may find interesting --- MK II crank vs. another little crank you'll recognize.

Brodak MK II Brodak12
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Post  Ken Cook on Wed Jan 02, 2013 3:15 pm

Kris, the prop I was using was an APC 5x3 on Sig 35%. Fred, I see your point. I own the engines you mention and just having them I feel is quite cool. I certainly don't use any engines straight out of the box. Even my Norvel's are getting a work over as I'm trying to get the max out of them. I just enjoy fiddling with all of them and using them. I don't like to leave stuff on a shelf. Ken
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Post  fredvon4 on Thu Jan 03, 2013 7:35 am

Not really trying to make any particular "point", and not trying to hijack a good discussion

Asked another way... does the Brodak MKII or the Norvel long/short nosed .049s have enough a user base to be supported into the future? Is one preferable over the other? Does either have a known weakness? How do either stack up to a Cox Medallion or TD for power, ease of use, weight...etc?

New TD and Medallions are still obtainable but usually are in the $60~$75 range and we know there is a finite supply of rotating parts and cylinders

Back on subject: You mention a friend with a machine for polishing your cranks. Is there a preferred method for polishing a crank without using a sophisticated machine?

As I read you and Rusty and Paul G suggestions on polishing cranks to mirror finish I often wonder what I have here to do this fine work on these tiny parts. I have not done it yet ( I don't have any junk parts to practice on.) but was thinking about chucking on nose of crank in my drill press and fitting a 3 inch cotton buffing wheel to an angle grinder with shield removed and using stick polishing compounds
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Post  RknRusty on Thu Jan 03, 2013 9:38 am

fredvon4 wrote:...As I read you and Rusty and Paul G suggestions on polishing cranks to mirror finish I often wonder what I have here to do this fine work on these tiny parts. I have not done it yet ( I don't have any junk parts to practice on.) but was thinking about chucking on nose of crank in my drill press and fitting a 3 inch cotton buffing wheel to an angle grinder with shield removed and using stick polishing compounds

Since my name was mentioned, I'll chip in here. I'm not a machinist and I don't have any machine tools, I'm just a usually lucky hack. What I refer to as crank polishing in my shop is to gently clamp the crank web in a vice with a rag to protect it. I cut a 1/4" strip of 1000 grit wet/dry sandpaper, about 8" long, and wet it with light oil. I use Remington "Rem" gun oil, which is lighter than 20w 3 in 1. Sewing machine oil might work even better, it's 10w. The lighter the better, I think. Then I give the two crank bearings the shoeshine action. I make sure to give the surface a buff as evenly as I can all the way around. It gets off the tiny scratches around the surface. I don't force the issue on any stubborn scratches. The aluminum journals on the crankcase are too tender to buff with my crude methods.

Usually the front bearing needs it more because of being dry started before oil makes it down the groove on the first crank of the day. That's why I always add some oil or fuel behind the drive plate before cold cranking. Dust and dirt also makes it's way into that area to grind on it.

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Post  andrew on Thu Jan 03, 2013 11:28 am

fredvon4 wrote:

Asked another way... does the Brodak MKII or the Norvel long/short nosed .049s have enough a user base to be supported into the future? Is one preferable over the other? Does either have a known weakness? How do either stack up to a Cox Medallion or TD for power, ease of use, weight...etc?

Fred -

The following are strictly my opinions and you may get better comments for others on the forum.

Unless you intend to fly formal competitive combat with CID restrictions, I would be inclined to move out of the .049 displacement up to .061. Both NORVEL engines weigh about the same with muffler, but you get 25% more displacement. Secondly, NORVEL production of the .049 is currently suspended due to the market shift to the .061 .

Brodak: Eastern European, $10 less than the NORVEL (eBay can be a good source), plastic backplate, parts available, 3 bolt head with std. plug, no muffler. Can be made to perform, but will require the type of work Ken has done.

NORVEL: Eastern European, metal backplate (pressure tapped backplate available from NV Engines), muffler, parts available, multiple plug and head combinations possible.

If you read other forums, the Brodak engine usually gets much less press than the NORVEL, so I think the market share tips to the NORVEL --- which may tend to keep it in production. Secondly, the NORVEL can go both ways, R/C or C/L. NORVELs can be less user friendly when initially breaking in, but the Big Mig model is easily managed after you become used to it. NORVELs will run well with little extra work. Mufflers are required at many fields, so that may eliminate the Brodak from some circles. One decided advantage for the NORVEL is the number of readily available head/plug combinations. You have the option of the standard NORVEL plug with head clamp, a standard COX head, the COX insert plug with head clamp, and the Galbreath head/NELSON plug performance combo.

My selection for a good, well performing engine (not classed a high-performance) would be a NORVEL Big Mig .061 on muffler pressure with a Galbreath/NELSON combo. If you want to add a little more excitement, then run the AME .061, W/ or W/O muffler on backplate pressure.

I think Rusty has had some pretty lively flights with his NORVEL.

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Post  RknRusty on Thu Jan 03, 2013 12:41 pm

andrew wrote:...I think Rusty has had some pretty lively flights with his NORVEL.

Haha, that's very true. I've turned some exciting circles. More to come when the weather quits sucking.

I recommend getting a starter spring, at least for the break-in runs, when it can be harder to start. I had a hard time finger flipping my new one, but once I got it running, it quickly got easy. I used a low compression Cox head to get it cranked the first time too. After that, the standard Norvel head powers it extremely well. I haven't tried my Galbreath on it, but Bernie's medium drop-in plugs work as plug replacements with either the stock head clamp or Bernie's Merlin head clamp. Any head and plug combo that fits a Cox will fit a Norvel. All stock plugs and replacement parts are sold by NV Engines.

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Post  fredvon4 on Thu Jan 03, 2013 1:51 pm

At the risk of totally hijacking Ken's superb thread.... I bough a Norvel Big Mig .061 once Rusty got his running. I am much impressed with the design, fit n finish, and machining of the lil bugger...waiting for warmer weather to break it in.

Back to Brodak MKII .049 Vs any other .049 currently available to purchase

I guess I am fond of Ken's exceptionally well written and informative posts....That said, I was about to buy one each of the "no longer in production" Norvel .049s. One long and one short nosed version, Simply due to being very impressed with the Big Mig.

Then Ken seems to claim the lowly (my opinion influenced from other forums) Brodak MK II as a viable engine with much potential.

I am changing my mind as I write this to getting TWO of the Norvel short nosed $55 motors and a few spare parts before the supply is all gone.

Andrew, Thanks, your idea about the .061s (1cc) being more power in close weight package is noted

My round about questions are trying to decide if I am missing some critical information, and the Brodak is a better idea from a bang for the buck point of view

FWIIW...I doubt my front yard sport, non competitive, flying would ever justify the high end FORA/PROFI/CYCLON/ expense. But it would help me some if part of the discussion could compare relative RPM and power of the high cost screamers to these relatively inexpensive engines we are talking about
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Post  Ken Cook on Thu Jan 03, 2013 3:02 pm

Fred, I highly doubt I would use the Brodak engine for any combat flying. Several reasons for that but most important, I just don't feel it has the umph to power the model correctly. For sport use I truly believe it would be a wonderful engine to own afterall it was designed to be a beginner engine. I found it to restart hot very pleasantly but I'm getting serious rpm's from my Norvel engines. I found that my planes and my son Shawn have been able to stay with most Cyclons when the Cyclon's are using 10% nitro and a Cox rubber ducky. Running a engine on the ground really doesn't do much in terms of stating engine performance and I'm not trying to persuade anyone into buying anything or promoting anything. I just see pictures on here being taken and I was just participating equally.

In the event your intent is to fly combat, I certainly would stick with your original idea and use the Norvel. I had some success with the AP Wasp as a inexpensive option, I also had some major problems with it. In the above post you stated "Out of the box" ready. Unfortunately, I'm not sure is that's an accurate statement to make on most brands. At least for me it certainly isn't due to certain particulars that don't meet my flying criteria. For instance, I wouldn't use a Norvel needle valve as it's just too coarse for my liking and even on suction it has some drawbacks. I'm also not fond of the stock Norvel plugs. Right out of the box I go with the Nelson conversion. I change the prop screws to allens and I use a different needle. You can see that 20+ dollars can quickly be spent in the quest of an engine to use. Just something to think about but I certainly feel that my experience that afternoon was a positive one with the Brodak and I would like to own one. I can't say that I'm overly impressed by the price tag, however I will say it doesn't fit my bill for combat it certainly has a place in the hobby and I would like to own it. Ken
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Post  fredvon4 on Thu Jan 03, 2013 4:05 pm

Note to self (in public)
Get some more Galbreth heads and Nelson plugs before they are unobtainable
Help Texas Timers deplete their stock of fine thread NVAs
Increase stock level of head shims to 30

Thanks for the discussion and opinions.
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Post  andrew on Thu Jan 03, 2013 4:36 pm

Ken Cook wrote:

For instance, I wouldn't use a Norvel needle valve as it's just too coarse for my liking and even on suction it has some drawbacks. .............Right out of the box I go with the Nelson conversion. I change the prop screws to allens and I use a different needle.

Agreed. I had intended to note the needle problem, but it slipped my mind (or my mind slipped) while typing. The stock needle can be very broad and may run thru several clicks before the engine responds, then the change is too large. It would be almost unworkable on strong crankcase pressure or bladder.

The NORVEL prop screw is pretty beefy, but I don't feel it's long enough --- the cranks are drilled pretty deeply. I try to cut my replacement screw length so it tightens up just before it bottoms out in the crankshaft. Maybe I'm being anal, but it can't hurt to add a little more stiffness to the crank. If you buy longer socket head bolts, you can get a partially threaded shank, i.e., the threads aren't chased all the way to the base of the head. This slightly larger diameter will better fit the NORVEL spinner/prop washer. A little measuring and cutting will then get the maximum length of the screw into the crank.
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