SGC

I got my first QueenBee recently , it was well used and with a bent rod. Needing a new piston /cylinder I looked at fitting a TD09 piston/cylinder.
Well initial fitting of one of my TD cylinders shows they physically fit and will clamp the muffler ok too.
Next was to fit up the piston inside the cylinder and take some measurements of bore /stroke and observ the transfer and exhaust porting- still looking good.
So I ordered a new TD09 piston/cylinder set from scallywag, it arrived yesterday.
Now the biggest problem with the conversion is the 074 has a smaller crankpin than a TD09- bush it ?? No , bush would be too thin for reliable opperation, also its better if the hole centre is dropped slightly to allow the piston crown to reach the top of the cylinder, hmmmm how too.
OK I'm going to braze the bigend hole up with Brass and redrill as per drawing , this will give a brass bushing and the desired repossitioning of the hole centre.
Maybe a couple of weeks befor i can get access to oxy equipement to do the brazeing, but all is looking good, need to make a gst to go under the muffler as the finning on the new cylinder is different to the older TD cylinder i initially tried, nothing to difficult or troublesome.
So hopefully I'll have some No's in a few weeks and hopefully they'll be good.
Stewart
Heres the Bore/Stroke measurements i got:-

TD09 - 1.5cc
stroke 11.9mm
bore 12.6mm


QB074 -1.31cc
stroke 11.2mm
bore 11.7mm


QB-mod - 1.41cc
stroke 11.2mm
bore 12.6mm

Exhaust port is 3.9mm high, piston now doesnt open the port fully but
3.2mm opening should be plenty.Also seems to be sufficient transfer
opening. QB has smaller crankcase volume than a TD so transfer pressure
should be better.
Stewart

SGC

The engine modded as above will have the same working stroke as an 09, ie from TDC to exhaust port opens , but the exhaust and tranfer durations will be reduced , but as these are quite large on a TD the resulting durations still look good.
Stewart

skaliwag

My Feedback: (1)

Hi Stewart..... I wish I had known this is what you wanted the parts for, I would have sent a fibre washer that I think you need. It is a standard plumbing part but if you can't come up with one let me know and I will round one up for you.

combatpigg

My Feedback: (3)

SGC, sounds like a clever way to get a Queen to earn her keep.

SGC

Thanks , I'll try my local plumbers first seeing its a plumbing item.
Cox really missed the boat on the QB design. It has so much untapped potential, if I had a lathe I'ed do the obviouse and make it a disk or drum induction, I'm sure theres added performance there too.
Hopefully with the more sedate exhaust and transfer times it'll swing a bigger prop for more thrust.
Stewart

SGC

CP ,
Well I hope it is, so far it all looks good, only the prop No's will tell the true story, but more capacity certainly cant hurt.
Stewart

combatpigg

My Feedback: (3)

I bought one based on a Chris Chianelli engine review and it had almost no compression seal and it was tightly fitted in the bottom end. I sent it back to COX and demanded a running QB in exchange. All COX did was send back the same engine, telling me that nothing was wrong with it. To make matters worse, the engine was supposed to power a COX ARF trainer that was so flimsy that it couldn't be trimmed for hands off flight. Since then, I've made it my mission in life to pass the word to all that COX sucks, approach their offerings with caution.

SGC

CP,
Saddly a lot were disapointed to find all they had was an overweight motor that was about the same output as a BabyBee, I bought this knowing its limitations and intending to do this mod, and hopefully getting something usefull in the end.
Nothing ventured as they say .
Stewart

skaliwag

My Feedback: (1)

My question is ...what makes the QB the week Sister. What would need to be done to make it run some where inbetween a good reedie .049 and at least a Medalion .09?

combatpigg

My Feedback: (3)

It's been many years since I've held one in my hand. From what I remember the prop wouldn't flip, the crank wouldn't turn freely and the cylinder wouldn't pump up and hold any air pressure. COX must have had little or no quality control with this engine. In the right hands and with the .09 parts, I'll bet SGC gets it going real good. My only question is, how do you know that the strength has been returned to the rod and ball socket after doing the hot work? I realize that a quenching is required, but if it isn't done right, then the part can get brittle.

SGC

CP,
Im makeing a split heat sheild that will clamp on the rod to draw heat away and stop it traveling up to the ball socket and also sheild the piston from the heat of the brazeing. As for the lower-heated part of the rod I think just letting it cool quickly by the action of the heatsink will suffice-I dont want it to become brittle by quenching.
This being a used engine, the crank fit is good and free but without slop. Even with a sloppy bigend(unbushed) it rocks back n forth several times (about6)after flicking.

skaliwag,
The working stroke of the QB, TDC to exhaust is quite short at approx 8mm, wereas the working stroke after fitting the 09cylinder will be approx 9mm the same as in the TD09 an increse of 12 1/2% in the power stroke quite a bit when combined with the increased bore size.
Stewart

digital_trucker

Geez - I must've been one of the lucky ones. I got one of the early Queens, and it ran like a champ. My only disappointment was the throttling wasn't as effective as I hoped it would be.

MJD

My Feedback: (1)

I had an early QB from Coxes pre-acquisition days, and while it ran it was a total dog for power and the carburetion was primitive and cantankerous. On a powered glider that would happily climb on a Black Widow or TD .049, the performance was disappointing. It was a heavy substitute for a middle-of-the-road .049 in my opinion, the only redeeming quality that it had a throttle that sort of worked. They had one thing right in that some people wanted a small throttled engine, but the execution of that concept left tons to be desired.

As to anything from Cox since it's acquisition some years ago - toys and garbage, but that is to be expected from a company run by a former toy company exec whose only mantra was profit. Inside word I had recently was to avoid the new ARF's like the plague. Now that it is apparently in other hands I wonder what the next evolution will be.

Considering the BS that goes on with product reviews, the only way I buy stuff is if I hear positive comments from what I feel is an unbiased source, or if I make what I consider an educated decision on my own.

digital_trucker

Ayup, 'primitive and cantankerous' pretty well describes the carb. Full throttle waswn't wide open, but reliable idling was another matter entirely. I never could get it to be consistent. I wound up just using it like and on/off switch. At full bore though, mine swung a 7x3 well. I'd used it as a replacement for a black widow and got a little better performance on the top end. Not being an expert, I suspect the main problem with the carb was the apparently sloppy fit of the barrel.