t_kwink

Are there any web sites out there discussing performance mods and technical data on the cox reed valve .049's? Information on the different cylinders and glow plugs used and the results of the different combinations would be very interesting and helpful.
Wink

BMatthews

You're probably in the heart of the most active Cox forum right here. I've cruised around the web quite a bit and never found such a concentration of knowledgable folks as right here. Ask away or tell us what you've got for engines, parts and what you want to achieve and I'm sure you'll find out what you want right here.

And a hearty WELCOME TO RCU to ya!

My own best reedie performance from my 1/2A reed combat days was a 290 (twin bypass flute) cylinder with a loose but not worn out piston, a straight cone type mid compression glow head, Cox grey 6x3 or 5x3 depending on the mission and 30% nitro fuel. Didn't have a tach in those days but it sure screamed and was as fast or faster than my competitors. I'm pretty sure the piston to cylinder fit was the key, It had to be loose enough that a dry piston would fall clear through the dry cylinder with no hanging up but tight enough that it would still pop nicely when flipped over. Rolling the piston through the compression stroke with a wet prime and an ounce of torque held on the prop tip produced a lot of bubbles and it would ooze through the stroke in about 3 to 5 seconds when doing this. Other than that just be sure the crankcase bearing surface and crankshaft jounal is smooth with no galling and that the piston ball socket is riveted down for a no play but loose fit.

nekked_man_2000

check out the forum at clstunt.com, there's a guy that hangs out there as Designman, larry Renger I think, I think he actually did some of the r+d at cox at one time. Anyway, he has lot's of informative posts. Just do a search and you'll see. He may hang out around here too??? I don't know.

Tim Wiltse-RCU

Wink,

Where in NC are you? There is a pretty good sized group of 1/2a flyers here on this board from NC.

Later,
Tim

t_kwink

I have just recently moved to Mooresville (just north of Charlotte). I wanted to make it to the fun fly this past weekend that I read about, but my wife is recovering from surgery, and needed attention.

I was looking for a good cylinder/head combo to freshen my black widow with, to run strong with a 6-3 prop on a sport plane. I am aware that there are three different glow plugs with obvious different compressions that can be identified by the number of fins. I'm not as sure about the cylinders. I know they come in either open or split exhausts, but I am not sure of what other differences are available. I assume the internal ports differ on different models?

By the way, are all the reeds the same? I assume they are.

Has anyone experimented with drilling out or reshaping the intake venturi?

BMatthews

The Black Widow cylinders are fine but as I said the piston to cylinder fit is important. You need to find some pistons to play with for the fit.

The racers drill out the venturie to .075 or so but it reduces the fuel draw so you can't stunt the engine as well.

t_kwink

I will have to look at the fit and pick a good one I guess! What is the factory venturi diameter?

Tim Wiltse-RCU

Wink,

I am just "down" the road a little in Concord. Bailey Harris, another 1/2a flyer is down in Mint Hill. I am in fact a 1/2a only flyer myself. I eat, sleep and dream things 1/2a! A stock Black Widow tank venturi is either .081 or .082 (I forget ). I go to .093 most of the time. But like I found out the hard way it depends on how far above sea level you are. A good basic cylinder combo is the #1 cylinder (twin bypass with sub piston induction) with a basic low compression head. If you do a search here on RCU you will find a piece I posted last year on "Cox Reed Valve Performance". Use that as the search name. Like Bruce said THIS is the place for 1/2a info! You will find no other better source. Here is a picture or two of some engines I have built.... the last picture is of my Sniper DR .020 that I am working on bringing to market.

Later,
Tim

t_kwink

Thanks for the info guys! Tim, I know my way around Concord a little. I travel between here and there ocasionaly for work. We'll have to hook-up some time!

ptulmer

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Tim,
nice engines and site. Gotta go get a mop for the drool...


ps. be talking to you soon about a witch doctor!

t_kwink

Tim, I love the look of those little engines!!! I got a chance to read through those reed valve modifications and just wanted to say thanks, they are very interesting. Have you tried most of these mods? It sounds like it would take some time to completely go through one of these gems, but I'll bet it's worth it.

Wink