I have an OK SUPER 60  i know nothing baout sparky engines what do i need to get this engine running thanks for any info .

Brad.  If you need help with the spark ignition system/hookup, contact me and I think I can answer any questions.

Floyd Carter
Eugene, OR

Jim Kraft makes spark ignition look really easy.  After watching him fly flight after flight, trouble free, with spark ignition engines, I had to try it.  I copied his setup as closely as possible and I've been happy with the results.  Read this page, http://www.modelflight.com/ignition.html.  It'll tell you all you need to know to build a transistorized ignition circuit.  If you can operate a soldering iron, it's a very easy circuit to assemble.  Just follow the diagram and the tips.  The TIP42 transistors can be found at Radio Shack cheap, and they've worked OK for me.  Used Modelectric and Aero Spark coils can be found on Ebay, most of the time.  3 AA or AAA NiMH batteries work well for power.  Running on 5% nitro, 25% all castor fuel, they're almost as easy to deal with as an old glow engine. 

In my experience (admittedly rather limited), the "Larry coil" doesn't work.  The same applies to vintage spark plugs.  They work great until the electrode pulls out of the insulator.  It's easier just to start with a new plug.

As mentioned, OK engines are of varying quality.  Sometimes you can have one with great compression, that runs great, others don't or hardly run at all.  I've got an OK Super 60 that runs great on the test stand, and I'm still cautious to build a nice plane for it.  I'd run the engine more than a few times on the test stand before building a plane specifically for it.

Hello Brad,
I have quite a few OK 60s and They all seem to run extremely well. If you want to know how to run them in the old style (no transistorisedignition). Look up some past posts by Bob Zambelli. he runs them in the traditional manner with petrol oil mix and has them well sorted. Flloyd Carter is the man for transistorised ignition and both of the above gentleman have given me lots of information and tips via PM's. Contact them for a really in depth help session! I can't praise them enough for the help they gave me.
  Looking at some of the other responses, there are one or two points to be aware of. My Super 60s have good compression and start easily by hand. I know of (and have seen) others with much worse compression, that are difficult to handstart. All of the latter will start very easily with an electric starter. I believe that many Super 60s were used in tether car racing, back in the day and some form of starter was invariably used to get them going. The downside of this is that the bearings are fine, but many Super 60s seem to be made with a weak wrist pin (some sort of bronze?). All of my examples are fitted with steel wrist pins. I don't know if OK did this at some stage or if it is an aftermarket conversion. I have never seen anything but steel in this area and I have seven of the OK engines (did I say I liked them?). Any feedback on this would be welcome as I have never been able to work out what was going on here.
  The comments on old plugs are a little harsh. In my experience of sparkies, old Champion plugs are a pain, with the center electrode blowing out. Other makes have not had this problem. Modern plugs are well made in this respect, although performance can be down on some of the old plugs, much to my surprise.
  About the only available new coils are the Larry Davidson ones, which are a literal Chinese copy of a well known US make of a few years ago (memory not working!). These coils are fine in a traditional setup, but can give huge problems when used with transistorised ignition. Normally they simply don't work, at the risk of Larry suing me. Flloyd told me that the main problem was that the TIP42 transistor had a very low reverse breakdown voltage. He recommended a type with a much higher reverse breakdown. I tried these transistors and although some Larry coils then worked, others did not. Still you can buy them and still use them in non transistor ignition circuits and there they have given me no problems whatsoever, just be careful if you go the transistorised route!
  I have not checked the RPM of my engines, but I guess they run at between 6 to 7 thousand RPM. At these revs, they do vibrate much more than modern engines. Don Howie, in Australia, says that with the right prop (I think it was an APC of about 13x6 or 7). The engine gets past this vibration region and smooths out. Unfortunately at higher revs, the integrity of the engine becomes suspect. I have managed to destroy one at these sort of higher revs, so be warned!
  About the only real problem with the OK and other similar sized sparkies is the noise! If you run on petrol then a normal expansion type muffler will get the engine very hot. That is about the only reason that I run on castor / methanol brew, they do run cooler on such fuel. A tongue muffler can easily be fabricated for a Super 60, but it doesn't do much muffling and in the UK, noise is bad news. I have copied Bob Zambelli's idea of fitting a very long, large volume expansion exhaust fitted to the fuselage, with the exhaust stack fitting into a slit. A little high temp RTV does a poor sealing function and the noise is then acceptable.
  I have been running sparkies in stunt aircraft for a few years now and it is great fun, I am still learning, so any comments or feedback are most welcome.

Regards,

Andrew.

Hello Floyd,
Apologies for misspelling your name. Re Larry Davidson copies of the Getttig coils. I have tried several without transistorised ignition and they are excellent coils and lightweight to boot. I first came across these coils several years ago. and didn't realise from whence they came. They looked like the Gettig coil dimensionally, but obviously were not. I was approached by two people in quick succession that were trying to run them from the simple TIP42 type circuits. Apart from an occasional pop and bang, this set up didn't work. I swopped the coil out for a known good one and all was well. My memory may be at fault here, but I thought that I discussed the problem with you via email (apologies if it were someone else). The recommendation was to use a transistor with a higher reverse breakdown voltage. I obtained a dozen of the recommended transistors from a specialist dealer in old transistor types and built a version of your TIM 4 ignition unit. The first two Larry coils then ran well with this set up. I have had one further example of the Larry coil through my hands and this one ran with the TIM 4 circuit, although it was missing quite a bit.
  To summarise, there does seem to be a problem with some coils in some transistorised circuits. I have seen other Larry Davidson coils run very well indeed with simple TIP 42 circuits!
  I have enough old coils to keep me going for years, so I have not purchased any of Larry Davidson's coils myself. The ones that I have experience of, had been run for very lengthy periods when trying to start the engines. It could well be that the people involved ( they had zero knowledge of sparkies) had overheated the coils during this process. The lack of starting could have been down to inexperience or something else not being correct. I am simply reporting what I have observed. I can see no reason why the Chinese made coils should be any different from the original Gettig coil, they do run extremely well in conventional non transistorised form. so I am unsure why I have seen problems. I have tried to analyse the problem and have used a high voltage probe and a storage scope to take a look at the wave forms involved, without being able to come to any conclusion. The coils work without the transistorised circuit, some coils don't work with a transistorised circuits and these same circuits work with other makes of coil!!!!!!!!
  I don't want to get into any arguments, something odd is going on and I wouldn't mind knowing what that is. I think that Larry Davidson should be commended for taking the trouble of supplying an inexpensive lightweight coil and I would not wish to say otherwise. I believe that the reverse breakdown voltage of the power transistor would be the most likely explanation as you (?) suggested.

Regards,

Andrew.

Hello, Gents.
I too favor the OK Super 60 for a number of reasons. It is very reliable, easy to start, fairly light and quite reasonably priced. I've sold a few brand new ones on eBay for right around $100.00.
There are a few mods that are easy to accomplish and, in my opinion, really help the overall performance.
1) The original bronze wrist pin should be replaced. I have seen instances where they actually flex, causing the bosses inside the piston to fracture.
2) I remove ALL gaskets and substitute Loctite Anaerobic Gasket Eliminator, item number 51817.
3) I use a Super Tiger needle valve assembly.
4) I used 6-32 Allen cap screws for cylinder hold-down and backplate attachment.
5) I reverse the exhaust to where it points outside the circle.

When I first started using the S-60, I noticed that the points looked very familiar. Turns out, they are identical to those on my 1967 ALFA Romeo. Only the pivot bushing has to be reamed a bit to .189.
Regarding the muffler that Andrew mentioned, I am really pleased with the results. Being of substantial volume, it allows the exhaust to expand a bit, therefore dissipating some of the energy before exiting. Some high temperature RTV seals it well. Note that it is mounted to the airframe, not the engine.
As far as ignition goes, I have used only the standard points/coil/condenser/battery combination with perfect results. I understand that Floyd's transistorized system is excellent and many people favor it over my setup.
Spark plugs: I have had TERRIBLE results with Champion plugs. My preference is the AC - hundreds of flights and I only clean it once a year.
I've had the best results with some old Top-Flite 12-8 wooden props.
75% premium gasoline, 25% castor oil and a touch of nitrobenzine.

I will be submitting an article in the next CL World describing the fitment of the muffler to the OK S-60.

I hope this helps.
 Bob Z.

Floyd,
All of the Larry Davidson coils I have had through my hands have always worked, without a transistorised switching circuit. The problem arises with some transistorised switching circuits. They simply WILL NOT drive a Larry Davidson Coil. Other circuits WILL drive the same coil. You can take ANY of the transistor switching circuits which WILL NOT drive the Larry Davidson coil and try them on ANY other make of coil and the system will perform. I have had one TIM4 circuit (your original manufacture) which would only drive a particular Larry Davidson coil with lots of miss firing. The same TIM4 circuit drove any of my other coils flawlessly.
  I have used DB244 transistors in my own brew circuits and have never had a problem driving anything. I have also seen the standard TIP42 circuit, drive a Larry Davidson coil.
  There is NO doubt that the Larry Davidson coil will not function with some transistor drivers. This has been noted by two Australian friends, who have been flying ignition since the late 1940s, by myself, by Andrew Hathaway and indeed by Larry Davidson himself. If Larry Davidson admits there is a problem, it seems odd that you should deny that there is.
  I simply avoid the problem by using other makes of coil, including some that I have wound myself. It has been maybe two years since I saw these problems. The problem is real and I still cannot figure out what is the cause. Reverse breakdown voltage of the power transitor is favourite. But these self same transistors don't breakdown with other types of coil.
  I suppose that we shall not be able to agree on this aspect of Mr Davidson's coils. For those that do experience this odd behaviour, simply do away with the transistorised ignition, save a few grams weight and enjoy them as they used to work, back in the 1940s. Used like this, they do work very well indeed, as good, if not better than the old coils!

Regards,

Andrew.
 

I agree that the large Aero Spark coils are awesome!  However, they weigh 2 oz.  They were intended for tether cars where weight isn't a factor. 

The Gettig and the Larry coils are under 1 oz.  They provide adequate spark, but not excessive.

I repeat my offer to test and analyze any Larry coil for you which is suspect.  I have yet to find a bad one.  Larry D. is a good and honest guy, but he doesn't have the test equipment, or the expertise, to diagnose a bad coil.  I do.

Floyd

Once again, the transistor driver is nothing more than a switch.  As long as the driver doesn't suffer from "secondary breakdown" (transistor voltage rating not high enough), charge storage (slowing the turn-off), and the "on" voltage drop across the transistor isn't excessive, then the coil has no way of knowing where its drive current came from!  The primary DC resistance of Larry's coils is 0.8 Ohm, the same as Gettig, Modelectric, etc.  Inductance might be a bit lower because the small coils have less iron in their core.  But this would not make some of them good and some bad because the core material is always the same.

I have no dog in this hunt.  I stand to gain or lose nothing by it.  I am only curious and wish to solve the problem, if one exists.

I have provided transistor coil drivers since 1980, as Aero Ply Research Co.  I started with capacitor-discharge units, then went to the simpler switching transistor circuit.  I still supply Larry Davidson with the TIM-4 driver, at about 30 per year, depending on his sales picture.

Floyd

From my point of view, there are already a few viable workarounds for this problem.  I don't really see a need to find more solutions.  I don't have an axe to grind either, my intention was only to recommend what's worked for me, and point out a couple potential pitfalls.  The Larry coil I had never did much more than the occasional pop, except for dripping melted wax, and eventually the high tension lead terminal fell off.  Between being obviously damaged, and either lost in the shop or long since tossed in the garbage, it's just not worth messing with. 

The Aerospark "Featherweight" coils I use, weigh 1.25oz and work great.  I can't see a .5oz being a major concern on a 50oz .60 size plane.  There's more potential in weight savings by using different batteries or a different engine.  The only real advantage I see to the Larry coil is that it's available, but I'd gladly trade availability and the weight savings, for a more dependable coil.

Andrew T:

I'm curious about your use of a long expansion exhaust for the OK 60 to reduce noise. I would like your comments here, if you'd be so kind.

I've got an Ohlsson 60 (the 1941 version) that needs to run on petrol and caster only - thus it really does bark. Given the noise level, I've confined it to short bench runs. The advice I've heard so far is that any kind of muffler would cause problems with heat and reduced power. I really don't want to build and fly something for it without reducing the noise a bit. Might have to look into the approach you've suggested to see if it has any merits for this motor.

Thanks.

Dave Mo...