RE: cox surestart engine help
 

It wasn't crash-related. I would assume that the piston wasn't as stout as one in a TD. It had a lot more power than with the proper head, but obviously there's a price!

RE: cox surestart engine help
 

Hello again, can someone tell me how much weight a surestart can handle?

RE: cox surestart engine help
 

Remby,

Are you familiar with the TD glow heads? They have a "squish band" which is a near-flat lip that extends into the cylinder, then a much smaller cone than the standard glow head. This allows for a much higher compression.

Because of tolerances, some may touch the top of the piston if only one glow head shim (gasket) is used. If you play with this setup, use at least three gaskets to start, then add or remove gaskets to get the best performance for your setup.

If you are not willing to experiment, I would suggest the standard glow head with one gasket.

If you wish to experiment, you can also get an OEM setup such as the Galbreath/Nelson setup or the NORVEL setup.

Remember, if you try for maximum performance, you must be willing to occasionally break some parts.

George

RE: cox surestart engine help
 

gcb;
Yep, thats about what I see, and do. The Galbreath setup gets three, and at least two with the H.C. Any other ways the H.C. heads can do damage, something to look for?

Digital_Trucker;
Did the engine have sub-induction? Flown for many years with Cox, and have never seen that from just running a engine. What is the % of nitro you are using? I use 25% .

JasonFalls;
Sorry for the hijacking of your thread. The surestart can handle as much as a Black Widow, I would guess 18-20oz would be about the maximum for R.C. flying, less with control line. Control line interest? Look into Carl Goldberg for the Whizard, the 52 foot line trainer and wonder. Also, lil jumpin bean, great 1/2a control line plane. Even a plastic cox model C.L. will get you going, but they can be pricy. Good way to start though. WELCOME!

RE: cox surestart engine help
 

Remby - dunno about the sub-induction (as I don't know what that IS). It was a stock Cox Black Widow, just with a TD head. iirc, I was running 10% or 15%.

JasonFalls - I can't say about weight in regards to control-line, but with R/C, weight is important, yes - but it all depends on the type of aircraft. For example, I flew a powered glider with a 6-foot span that tipped the scales at just under 3 pounds on a reed valve .049. On the other hand, for a sport-type plane I'd say you'd want to keep the weight down to 24 ounces or less. Power-to-weight and wing area-to-weight ratios have to work together (not to mention what kind of perforance you're looking for). I'd say a Surestart should handle any craft normally capable of .049 power. You could always browse Tower Hobbies' website to get a rough idea of what size/type of planes go well with which power plants.

RE: cox surestart engine help
 

Here is my 2 cents on the Cox Sure Start. They are great little engine for a whole $7.00. In stock trim they will run a Cox 6x3 at 13,000-15,000rpm. This is a little weak even on Cox terms. While it helps with priming the choke tube hurts power a hair or two. Take if off the engine. Again in stock form it will have problems flying a "sport plane" at 24oz! Now a "sport plane" at 15oz is do-able. Something around 36" span and 260 sq in of wing area.

ALter,
Tim

RE: cox surestart engine help
 

Are the Sure Starts still available from Cox?

RE: cox surestart engine help
 

Yassir, they sure are!

http://www.coxmodels.com/prodinfo.asp?number=008901

RE: cox surestart engine help
 

Here we have a chance to steer this young 'un down the straight and narrow path to happiness in this hobby, and all you guys want to do is get this kid going with COX JUNK!! There are so many more arguments against starting a kid out with this stuff than there is arguments for going this route. Where should we start? Rod resets? Wandering needle valves? Availability of future parts? There are ways around all these hurdles, obviously....but for someone just getting started I think the AP .061 is cheaper in the long run and way more reliable. The RCU auction has had them for sale on occasion, but don't buy one that has been used.

RE: cox surestart engine help
 

Hey hey Jason ! If I had known you were still in HS I wouldn't have said tha, just kiddin ya, that's all!:D

Cox engines are very addictive, mainly because they are cheap and fun to play with. There is also a mountain of secondhand ones out there to seek and find if you like that sort of thing. I prefer the ones without the tanks such as SureStarts and the likes. They don't have that horrible little seal to go wrong.

I fully agree with what Tim Wiltse says about SureStarts in post 31. For $7.00 you simply cannot go wrong. I bought a bunch of them to cover me for spares in the future, should I need them. Removing the choke tube isn't bad idea either, as long as there is enough clearance for the venturi when the engine is screwed onto a firewall.

The worst feature of SureStarts that I have found is that the piston to cylinder fit can be poor, not all of them but quite a few. Even so, they will still run good enough for a CL trainer.

RE: cox surestart engine help
 

I believe at least some of the SureStart pistons are substandard. This was from three 5 minute runs with a TD head. I replaced the piston with an old Babe Bee one (in good condition) and it hasn't done it since.

RE: cox surestart engine help
 

The TeeDee head had three copper gaskets and I was running 22% oil. 12% of that was castor which I believe is enough.
The real problem was that the SS piston wouldn't tighten up it's ball socket. Every single run it came loose and had to be reset. Basically the rod end was working it's way up through the piston

Forgot to mention, the three 5 minute runs were with the TeeDee head, prior to that it had recieved about 10-15 minutes running with std compression and reuqired the ball socket reset every second run. Whoa.


Luke.

RE: cox surestart engine help
 

That kind of damage happened so quickly because the loose ballsocket [as delivered] allowed the piston to slam back and forth between the head and the ball end of the rod. These engines shouldn't be run until the rod is set and the NVA is sealed and clamped so it can't wander about.

RE: cox surestart engine help
 

Well, I set the socket before I start the engine. I always do especially with the SureStarts, they are so loose new I wouldn't consider starting one without doing it. Besides, you can't get a proper run with the socket loose like that.

I put a lot of thought into why the piston did this and so far all I can come up with is a poor quality/defective piston coupled with the higher compression of the TD head. One thing I did notice, the engine kept spitting black oil, i.e. something was wearing and not bedding in. I would check the engine each run, tighten the socket (again) find nothing else wrong and start it up again. Perhaps it had swarf or damage inside the socket ?


Luke

RE: cox surestart engine help
 

Luke --

I bought several engines in the last offering from COX models -- they were out of stock for some time and these are probably the last to be sold. The pistons in this last lot seemed to be softer than any previous engines. I cannot be more specific other than say that force needed to reset the socket felt lighter. I used the same hammer, reset tool and steel base that I used with other engines and overset the first piston.

These sockets just seem to take less effort to set -- so if you are having to reset after each run and punched a hole in the top, it may be a bad run of pistons. Some of the other members have also noted some piston swelling with later SS's when resetting.

RE: cox surestart engine help
 

I agree, some of mine have the soft piston syndrome. Effortless to reset and easily over-set. Either the metal quality was down or the hardening process didn't quite take. Perhaps. I might hock the softies on ebay or keep them for low powered applications. Or strip them for spares when they show that tendency.

It's all good ;)

RE: cox surestart engine help
 

Digital_Trucker,
O.K. then, the stock Black Widow, was it slit type exhaust? If so, it was NOT sub inducted. As far as I know, the only slit type that had sub induction was the Killer Bee.

This is interesting, as non sub induction may be causing the piston damage to happen. I have never seen this, in any of the Cox I have used over the years. Or, could be a problem with a few pistons from the latest sure starts?

How many have seen this?

RE: cox surestart engine help
 

The stock Black Widow had four slits for exhaust. I suspect the rod getting forced through the piston was a result of a TD head+two gaskets+never having set or reset the ball joint. In my defense, I was just a kid at the time. Ran like a scared rabbit, though!

RE: cox surestart engine help
 

Probably a number 6 cylinder. What year did you buy the Black Widow ?

Luke.

RE: cox surestart engine help
 

...which aligns perfectly with what Combat Pigg said. I always thought not resetting the rod joint would cause the rod to pull out of the piston but that is simply presumption on my behalf.

RE: cox surestart engine help
 

All you have to do to see if there is deck height interference is to bring the piston up to TDC, and see if it goes beyond the shelf that the head clamps against. If this combination of parts tends to do that, then the mystery is solved.
For normal engines, a little chunk of solder will tell you what your squish clearance is if you place the solder on top of the piston near the edge of the cylinder, then rotate the engine 360 with the head on, remove the head, then take the flattened piece of solder and mike it.

RE: cox surestart engine help
 

Luke,

FWIW a #6 cylinder has 2 large exhaust ports like the TD's.

LAter,.
Tim

RE: cox surestart engine help
 

[sm=confused.gif]There I go with the #6 cylinders again[sm=50_50.gif]


OK, the #6 cylinder is as you say, I have several of them and they are clearly stamped.

Here's the problem, I have fifteen cylinders with the same configuration as the #6 except they have the twin slit exhaust and no wrench flats. For the sake of personal convenience I have fallen into calling them #6 because I can't find a reference for this configuration and yet not one of them is stamped with anything. I keep refering to them as #6 without realising, basically they are a #6 except for the exhaust . It's an unconcious thing, believe me. I am not trying to mislead or make a pretense of being an expert, it's more an issue of thinking out loud. [&:]'

Now, for some more clarity, the Joe Klause cylinder number reference states that the #1 cylinder evolved into a twin slit exhaust for the Black Widow and was un-numbered in this configuration. So presumably Digital Trucker's could be one of these, evidence of SPI would prove it.

I blame Cox for all of this confusion, they should have stamped the damned things correctly in the first place.;)

RE: cox surestart engine help
 

IMO the #1 twin bypass, SPI, large exhaust cylinder never evolved into the common product engine twin slit that you see on some of the newer Black Widows. They are on those because Cox/Estes screwed up the engine line. The non SPI twin slits ended up on Black Widows because they stopped caring about what performace was[:o] The only twin slit exhaused cylinder that has SPI is the Kill Bee cylinder and of course it has the taller bottom slits.

LAter,
Tim

RE: cox surestart engine help
 

Luke if u trust me with that piston i,m getting a plating kit this week i could try putting a nickle or chrome or whatever kind of top back on it for u. If so pm me. Just a thin coat of some harder metal or add more copper?
Td