bogateer

I never realized there were so many different flavors of .049 cylinders. I looked around but couldn't find a concise compliation. Would anyone care to run through the list for us inquiring minds? Incidentally...where exactly are those numbers supposedly imprinted on the cylinders? I've never seemed to be able to find one. I know there are grooves of various numbers within the cyclinders...is this sufficinet to identify them or are there other factors? As a bonus question, could someone explain "SPI" for me or point me to a spot that covers it.

Thanks guys!

Rob

BMatthews

If someone takes the time to do this how about posting it in the Cox Reedie FAQ thread and then just link to it in this thread. That's something that would be good to have in there.

Jamtx

My Feedback: (2)

Try this: http://www.rcuniverse.com/forum/m_95.../tm.htm#958979

James

burtcs

Bruce: I already did this. It's on page two. Somebody isn't doing his homework.

regards - Steve B.

bogateer

Still don't see where there are any numbers marked on the cylinders. Is this a 1/2A version on the "left-handed smoke shifter"?

bogateer

Thanks for directing my to the Cox cylinder thread...it's exactly what I was looking for and I appreciate being directed to it...although it doesn't explain why Cox seems to have a "cylinder of the week". Any desire to explain the advantages of one type versus the other (up late one night and can't sleep)?

Thanks,

Rob

lukesp

Rob,

here's a number one. Can you see the number ?

lukesp

Here's a number two, not as distinct. The number is directly below the exhaust slot, in the centre of the cylinder. This is the other way Cox stamped the number.

I have found that number's 6, 7 and 8 rarely have the number stamped on them. I have several number 7's that are stamped and they are the same cylinder as the SureStart.

Luke

bogateer

Ok...cool...thanks

I would have never spotted that on my own. Clever.

bogateer

Sneaky...thanks

skaliwag

My Feedback: (1)

The Me-areotools site shows a Black Widow with the TD style exhaust slot... Have this engine ever had the two slit type a-la Sure Start?

Jim Thomerson

SPI refers to sub piston induction. The skirt of the piston clears the bottom of the exhaust port at top dead center and allows air to enter into the crankcase to supplement what is already there. Some Cox engines have it, some don't. There was an early ignition engine, the Howler, which had only sub piston induction for air. The fuel came in through a rotary valve in the shaft. If you do a search on Vintage and Antique forum you will find a picture and some more description. Engine was said to be very powerful and extremely loud.

lukesp

Yes, the Black Widow originally came with the number 1 cylinder, two bypass ports, SPI and the large exhaust. Good power.

It also came with the number 6 slit exhaust with no SPI and two bypass ports and it came with the Sure Start cylinder, no SPI twin bypass with little "boost" ports machined beside the bypass ports. I have three or four Sure Start cylinders that are stamped 7, so I am guessing that the Sure Start/late Black Widow cylinder is a number 7.

skaliwag

My Feedback: (1)

So If a new B/W has the S/Start Cylinder with the black plastic 8cc tank is it no more than a new Babe Bee witha TD spinner?

lukesp

Here are two shots of SPI, not the clearest but it's difficult to photograph.

Photo 1 shows the bottom of the piston visible through the exhaust slot, in other words the piston has come up past the bottom of the exhaust slot and exposed the inside of the cylinder.

Photo 2 is the same thing with light behind it to ensure you can see how to look for SPI. The piston is at the very top of it's travel, TDC (top dead centre). If the piston does not expose the bottom of it's skirt at TDC then the engine does not have SPI.

lukesp

I would guess so, with the larger tank. Don't forget, the Sure Start cylinder is quite a good setup. Also the Black Widow's came with the number 6 cylinder in both slotted and un-slotted form and none of these had SPI


The number 1 cylinder was probably the best setup because it had SPI, but does SPI work well enough to justify worrying about it ?
Number 6 and number 7 cylinders give excellent power once the compression is sorted out, and there is an abundance of Sure Start cylinders around.

personally I think Cox dumped all other cylinder configurations except for the Sure Start cylinder ages ago. Ain't nothing wrong with it for power once the compression is sorted out.

lukesp

If you want a good Black Widow go on ebay then look for one with the gold anodized back plate, non-slitted large exhaust and frictionless starter spring and you may find it has the number one cylinder, or it could just as easily be the number 6. It works and gives nice power either way.

After all, what makes a Black Widow what it is the colour, the tank, the backplate and the spinner. I have two genuine Black Widows that are not anodized black, they simply have the large tank with correct back plate and number 1 cylinders. Both have the early snap start spring with the red plastic disc.

Most of the black Black Widows I own have number 6 cylinders, slotted and un-slotted exhaust with no SPI. Unless we are going flat out racing I can't see any problem with number 6 cylinders.

Big Al-RCU

Speaking of the slitted exhaust ports, does anyone know why cox went to that? I’ve heard several reasons, but I just thought of another possibility.
Back 30 odd years ago a family member who worked in a large dept store, gave me a bunch of cox plastic planes. I think they were called the ‘Bushmaster’. Turns out after Xmas they were returned by the basketful. This stores motto was ‘Satisfaction Guaranteed’ so they took them back no questions asked but didn’t want the actual merchandise returned, (they were supposed to be scrapped locally). These engines had the large exhaust ports. It turned out that most of these returned engines would not turn over because something, probably a small screwdriver, had been inserted though the exhaust ports for torquing/removing the cylinder(?) and had kicked up a burr which (fortunately for me) was easily removed with a #11 knife. This store (and maybe cox) took a licking on this one and didn’t push the cox plastic planes so hard the next year. Since it isn’t possible to poke a screwdriver thru the slitted exhausts, that would resolve that problem, but of course I have no idea if that was a contributing factor for the redesign. Just a thought.
Al

BMatthews

That may well be the answer Al. I've also read some stories that the slits are less prone to spit out a flame from a bad prime and set the model, and possibly the modeler, on fire.

lukesp

The standard Cox wrench is equipped with a fork end to fit the exhaust ports for tightening the cylinder down.
Unfortunately if you aren't careful or firm with the wrench is slips quite easily and burrs the inside of the cylinder bore , in fact it does this with ease . I have done it myself until I learnt not to do it, I use either the flats machined in the top of the cylinder or cut my own flats with a dremel and a cutoff wheel. I find it difficult to NOT burr the damned cylinder if I use the old idea. Imagine a ten year old kid trying to do it.

The other reason which I have heard for the slits is fire, apparently people were priming through the exhaust port with the battery connected and the fuel would flash. the two small slits help arrest any flame that might happen. Sounds logical.

Oops, cross post with Bruce

Big Al-RCU

Yes guys I’m sure the safety issue of flashback is what drove the various mufflers, screen wire and slitted exhausts. But I was wondering if cox even knew that they were killing two birds with one stone. I’m sure (certain) this store (Wards, Cocoa, FL) was reimbursed for their come-backs. But, cox probably never knew the reasons, i.e., no feedback. I can also see a ten year old trying to remove a glow head but the cylinder turns on the crankcase. Since only one wrench comes with the plane, what to do? Either grab a pair of pliers to hold the cylinder (a no-no) or poke something thru the exhaust ports (a worse no-no). Surely must have been a very common occurrence. Just wondering how much of this got back to cox or if in the big picture of their huge sales it had negligible impact.
Al

lukesp

They were probably more worried about the potential courtcases from burns rather than the "my engine is broke" complaints, so as a guess I would say it was more about the fire than anything. I also had a chat with someone I purchased some parts from via ebay, he had worked for them at one time and a lot of his stuff was old returns, so I guess they knew what was going on re the cylinder/wrench jam syndrome.

I think the dumbest thing Cox ever did was to make a cylinder without the wrench flats on top AND with a slit exhaust. Absolutely no way to remove the cylinder without damage (unless you thought it through and used a wood block with an appropirate sized boring and a vise). They didn't seem to care about that. I have heaps of them and I have cut flats on the top of them all.
I have an early brochure from Cox touting the use of 0000 grade steel wool to de-varnish the cylinder. Something you cannot do unless you strip the engine, so they were well aware of the fact that you cannot own a Cox without stripping the thing down occassionaly. Someone wasn't thinking.

Luke

Remby

My Feedback: (3)

I also heard fire the reason for the slit type cylinder.I did many years ago have a fire on a Cox ,plastic control line, don't remember what I did wrong, if anything. Funny, but the Tee Dee never did get a slit type cylinder.

The sure start setup is good power, and it can be reworked to give more power by cutting sub-induction into the cylinder, not too bad a job. This works good, details in the sticky cox reed valve forum. For the cost of the sure-start, not too much to try it.

lukesp

I agree, the Sure Start cylinder setup is fine.

Strange to say but I have a number 4 cylinder which came on a TeeDee 049 (as it should) and it's porting is exactly the same as the Sure Start, two bypass ports with a "boost" port each, but it also has SPI and the large exhaust opening. The standard number 4 porting is two bypass ports machined into the cylinder as three grooves. Lots of breathing area. So this cylinder is basically a number 4 with SS porting.

Very odd.

lukesp

I thought I might clear up some unintentional BS on my behalf here. I have just been playing with my eight Black Widows and realised that six of them have number 1 cylinders. Two of them (Silver crankcase) have number 6 cylinders. Earlier in this thread I said that the majority of my BW's had number 6 cylinders.

I really detest it when people give out misinformation and here I am doing it myself!

Let's put it down to brain fade.[&:]


Luke.