Notices
Everything Diesel Discuss R/C Diesel engines here.

RJL head

Old 07-09-2008, 04:39 PM
  #1  
ebeneezer3
Thread Starter
 
ebeneezer3's Avatar
 
Join Date: Sep 2003
Location: Tucumcari, NM
Posts: 122
Received 0 Likes on 0 Posts
Default RJL head

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
Old 07-09-2008, 10:50 PM
  #2  
gcb
 
Join Date: Oct 2002
Location: Port Ewen, NY
Posts: 3,440
Likes: 0
Received 1 Like on 1 Post
Default RE: RJL head

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

George
Old 07-10-2008, 06:27 PM
  #3  
Lou Crane
 
Join Date: May 2006
Location: Sierra Vista, AZ
Posts: 711
Likes: 0
Received 1 Like on 1 Post
Default RE: RJL head

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...

Old 07-10-2008, 07:26 PM
  #4  
lildiesel
Senior Member
 
lildiesel's Avatar
 
Join Date: Nov 2005
Location: Cincinnati, OH
Posts: 754
Likes: 0
Received 0 Likes on 0 Posts
Default RE: RJL head

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]
Old 07-10-2008, 10:37 PM
  #5  
ebeneezer3
Thread Starter
 
ebeneezer3's Avatar
 
Join Date: Sep 2003
Location: Tucumcari, NM
Posts: 122
Received 0 Likes on 0 Posts
Default RE: RJL head

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
Old 07-11-2008, 11:29 AM
  #6  
gcb
 
Join Date: Oct 2002
Location: Port Ewen, NY
Posts: 3,440
Likes: 0
Received 1 Like on 1 Post
Default RE: RJL head


ORIGINAL: Lou Crane
...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...
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
Old 07-14-2008, 08:05 PM
  #7  
lildiesel
Senior Member
 
lildiesel's Avatar
 
Join Date: Nov 2005
Location: Cincinnati, OH
Posts: 754
Likes: 0
Received 0 Likes on 0 Posts
Default RE: RJL head

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,

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
Old 07-15-2008, 12:31 PM
  #8  
Lou Crane
 
Join Date: May 2006
Location: Sierra Vista, AZ
Posts: 711
Likes: 0
Received 1 Like on 1 Post
Default RE: RJL head

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!
Old 08-21-2008, 10:55 AM
  #9  
ddd
 
Join Date: Sep 2002
Location: Smyrna, TN
Posts: 413
Likes: 0
Received 0 Likes on 0 Posts
Default RE: RJL head

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
Old 08-22-2008, 07:48 AM
  #10  
mapnet
Member
 
Join Date: Dec 2001
Location: Mountaintop, PA
Posts: 65
Likes: 0
Received 0 Likes on 0 Posts
Default RE: RJL head

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

Maurice
Old 08-22-2008, 08:50 AM
  #11  
ddd
 
Join Date: Sep 2002
Location: Smyrna, TN
Posts: 413
Likes: 0
Received 0 Likes on 0 Posts
Default RE: RJL head

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

Bob Davis
Davis Diesel

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.