TD .049 and TD .90 engines
 

I was quite active using both engines 4-5 years ago but got involved in bigger stuff so these little engines have been setting on the shelf. Seems like the last time I used them I was having a terrible time keeping them running. This was going on for a month or so. They would run good holding them, but after I'd launch them, they would run like crap or quit. I've used them for years so I'm familiar with these engines as far as carb cleaning etc.

I was using fuel about 15% nitro with castor. Is it possible the 15% was the problem? I had a friend give me some 30% heli fuel. Think that would help? What percent nitro do you guys use?

I just read the post below "
[h=3]Request For Tee Dee Help[/h] Answered many questions I had.

20% all castor 25 to 35% nitro

I wish cox made a TD .90, that would be fun

Maybe I'm wrong and I probably am but, I thought they did make a TD .90.

Edit.......Sorry TD.09

Td .09.

No a TD .09 almost a .10 size engine now times that by 9. Would be around 1,200g or 42.2oz or 2.64 Lb. engine around 2.4 Hp.

There were TD .010, .020, .049, .09 and .15. They ran best on high nitro.....above 25% but there were fuels with higher nitro. I always used Missile Mist. It may have been 40% nitro. Someone will know. But would not be able to afford that now

bob

Lots of cool and interesting Cox info here: http://www.mh-aerotools.de/airfoils/cox_frameset.htm

40% is rather expensive, but the motors are pretty small, and a quart will last a season. Your car will spend more to drive it to the field. Maybe the problems the OP is having are from unfiltered fuel. The three holes in the venturi are pretty small, and get plugged easily. Could be overheating, getting lean at the end of the tank if it is a largish tank, varnish in the cylinder, low oil content, or air leaks.....

Very interesting thread.
I just looked through the 30 or so photos on that site - what history. I had never seen those historical photos before, and it is an interesting look in on production of these engines with the personalities involved.

Keep those engines running!

I've had excellent service from all of my Cox engines, TD s included. If you can't make them run there is a reason for it. My bet would be a tiny crack in the plastic front housing. I inspect them under strong magnification and an equally strong light. It's amazing what trouble the smallest defect can cause.

I run TD .049s often with 10 to 15% nitro and the performance is good.
The bonus is improved run times and glow plug life.

Although I prefer replacing the carb bodies if cracked, I have made very effective and lasting TD repairs by binding together the threaded collar with kevlar thread and epoxy (regular works, I just happen to have a spool of Kevlar), while the venturi is inserted to make sure it is on size.

I agree with CP on fuel, though I don't use 10% - .049's are quite happy on 15%. PW .020's are okay but needle better on 25%. .010's - not applicable.

About a large Babe-Bee;)http://www.rcuniverse.com/forum/atta...mentid=2156359

In the last three years I have been running 25 / 30 and 35% so far no burnt out plugs. 1 CL and 5 RC planes.
You can use a brass tube collar over the cracked carb body too, wick in some CA in the crack and then bind
with a tight fit collar will keep things going till you replace.

I wonder if he ever ran the Baby Bee would be loud for sure lol.

I like 25% as a general <=1/2A down fuel because they all like it, and it isn't hard on the .049's unless you suck at needling and prop choice. I run 35% when I want to run more, but my personal opinion is that above that is unnecessary due to the tradeoffs.

I've seen that pic but dunno where - is it a runner? My rough screen measurement shows it is about 3X scale, jeez must be 1.2 - 1.4 cu in. :D

Lol what about hand scale to engine?

http://www.rcuniverse.com/forum/atta...mentid=2156389

Per owner Burki:

Cox BabyBee 0.8 ccm
That one is 23.3 ccm
1200g
Fuel tank capacity is approximately 125 cc.
Bench tested and started right up
Says he wants to build two more at the time 2010
1/4 "-32 thread to use a glow plug