ebeneezer3

I presently have one on a golden bee type 049. It has a Davis crank in it. I haven't gotten around to run it yet. I don't know what to expect out of that RJL, don't know much about them.
I'm not sure what prop to use, I plan to start with a 6/4. If it runs good, I've no idea what to put it in. Any ideas? maybe a texaco?

Ted

gcb

Put it in the same ship you would as a glow.

George

Lou Crane

Ted,

Even with a Davis crank, try a 7-3 or 7-4 first. You may get enough RPM, at softer compression and a bit richer needle... thus less fiddly to work with...

If all is well, and you need a bit more - THEN try a 6-4 (or 6-5 if you find one). The only thing that annoyed me about the DDD .049 conversions was that a bit too hot, or overcompressed, might burn through the head seal - needing replacement before the next run. That was years ago, Bob D may have changed things since...

lildiesel

I've had some success with a Golden Bee running an RJL head and a DDD heavy duty crank. I do use a Sure Start style snap starter with it. Makes a nice sport engine with a 7x3 or 7x4 wooden prop. I've also bench run this set up with a 6x6 Graupner, a combination that would surely be way too fast for me in the air and probably break con rods on a regular basis.

There's a great thread in the 1/2A forum that in part discusses this conversion: [link=http://www.rcuniverse.com/forum/m_4085390/anchors_4085390/mpage_1/key_Cox%252C049%252CTexaco/anchor/tm.htm#4085390]RJL on a reedie[/link]

ebeneezer3

Thanks I'll read the thread, I still don't know much about these diesels.
I've got one of Lee Stengal's Humming Bird 049's maybe I'll stick it on that.

Ted

gcb

Lou,

That feature was one of the things Davis touted as an advantage of his head. The idea is that running over-compressed (and thus overheated) would blow the seal instead of your engine. Some like that feature, some don't. I do.

George

lildiesel

I like the burn out feature, too. It really started working for me on Pee Wee .020s when I went to a thinner teflon seal than Davis supplied originally. It was easier to cut new seals than go to the hobby shop and pick up another crank or a piston/cylinder assembly. A Pee Wee turning a 6x2 or 6x3 wooden prop is a pretty stout engine.

Lou Crane

GCB and lildiesel,

Noted and thanks! I'm one who didn't enjoy it, but then I tend to run engines continuously for several minutes at fixed needle in CL flight. Variable loads in maneuvers may have increased the frequency of burn-through, and too many times it was during a flight...

BTW, I think the Cox .049 conversion was Bob's first product... Sure worked well enough to kick off the great line he now offers!

ddd

Hi Lou,

The most common cause of disc burn out is a varnished (insulated) cylinder from running a lot of castor. when the Norvell .060 (6X4's) 18 to 19000 Rpm came out we started getting calls on excessive burn out which we attributed much higher power then TD's so we added an aluminum disc then teflon and the problem when away. The discs can be cut from pop can's.

Bob Davis
Davis Diesel

mapnet

Bob, Is the aluminum disc closest to the piston or is the teflon ?

Maurice

ddd

Aluminum first then teflon as we want to hold in the heat.

Bob Davis
Davis Diesel