My Tractor Forum banner

1 - 10 of 10 Posts

·
Member of the 0.4k Club!!
Joined
·
412 Posts
Discussion Starter #1
Two questions for you model engine enthusiasts:
a) Years ago - when I was an active RC'er - there was a company called Davis Diesel Development that made conversions for the more common engines around then (OS Max, SuperTigre, probably a few others I can't recall. Is that company - or one like it - still around? I always thought diesels were cool as heck - had McCoy & OK Cub diesels as a kid - but I never did try the Davis conversion & wish I had. Seems like the diesels always turned a much bigger prop than the same size engine on the nitro fuel.

b) Next question: I have a couple of Cox engines that have sat around for so long that they've seized up. What's the best way to get 'em loosened up?

Thanks in advance ..
 

·
Registered
Joined
·
300 Posts
A, it looks like DD is still around, the website is updated from the last time I looked a year and a half ago or so.

http://www.davisdieseldevelopment.com/

I was all excited about converting an OS tm .18 I have a couple years ago, but my job went south and it just never happened.

B, IMHO, just squirt some fuel down the carb and slowly spin them around until they loosen up.
 

·
Registered
Joined
·
5,115 Posts
Those stuck engines depend on the kind of oil that was being used. If they are real old timers and you were using castor oil then alcohol would be my choice. If later fuel was being used I've had good luck with Marvel Mystery Oil mixed 50/50 with alcohol.

Mike
 

·
Registered
Joined
·
609 Posts
My son has just started to get into RC trucks so I got my old Losi LST out to run with him. The engine was stuck good, I did a pb blaster soak, got it free and rebuild the thing and it runs great now. From what I remember from my plane days it should work the same way, but I have never took apart one of the plane engines.
 

·
Member of the 0.4k Club!!
Joined
·
412 Posts
Discussion Starter #5
Thanks for the update on Davis and suggestions on getting the old Cox .049 unstuck. I think I'll just try a good soak in a small jar of PB to start with & see if that loosens anything up. The MMO's a good idea, too. After being away from R/C planes for close to 30 yrs, I'm getting the itch again .. at least a little. The Boss may have other ideas, though. :)

Thanks again ..
 

·
Registered
Joined
·
90 Posts
I have a collection of model airplane engines and some get "Stuck" from the old fuel/oil residue when sitting around for a while.

The quickest way I've found to loosen them up is to take a gooseneck lamp with about a 25 watt bulb and just lay the engine on the bulb for 15 minutes or so to free them up so you can get them to turn over or take them apart.

Make sure you put metal parts against the bulb, not plastic as it could melt.

I use Marvel Air Tool oil to lubricate engines for storage. Some air tool oil will cause problems in diesels and make them difficult to start but the Marvel works fine. You can get it in Lowe's, Home Depot and many other stores.

The Cox Diesel conversions work fine on the TD engines but some of the reed valve engines have weaker crankshafts and break when deiselized. Davis has heavy duty crankshafts for the reed valve engines.
 

·
Member of the 0.4k Club!!
Joined
·
412 Posts
Discussion Starter #7
I have a collection of model airplane engines and some get "Stuck" from the old fuel/oil residue when sitting around for a while.

The quickest way I've found to loosen them up is to take a gooseneck lamp with about a 25 watt bulb and just lay the engine on the bulb for 15 minutes or so to free them up so you can get them to turn over or take them apart.

Make sure you put metal parts against the bulb, not plastic as it could melt.

I use Marvel Air Tool oil to lubricate engines for storage. Some air tool oil will cause problems in diesels and make them difficult to start but the Marvel works fine. You can get it in Lowe's, Home Depot and many other stores.

The Cox Diesel conversions work fine on the TD engines but some of the reed valve engines have weaker crankshafts and break when deiselized. Davis has heavy duty crankshafts for the reed valve engines.
Dan, thanks for the info. Applying a little heat - carefully - is something I haven't tried yet. The info on the reed valve engines is worth knowing, too. I think I still have one or two, plus the TD. Always enjoyed that TD.

If I try the DDD route, I'm thinking a little OS .10 I have would be a good candidate. Honestly, though, I'm half-way considering electrics - something like a motor-glider - just to avoid the fueling and exhaust clean-up. Never thought I'd reach this point. "Airplanes" and "electric" just don't go together in my mental picture. But things do change, don't they?

Thanks again, Dan.
 

·
Registered
Joined
·
90 Posts
John,

Many guys find the OS .10 works great with a Davis Diesel conversion head.
It's a very popular combination and that same head also fits a Magnum .10 and a Thundertiger .10. With the Davis Diesel head you can turn a larger prop with more torque at a slower RPM which also cuts down the noise.

Electric power has really come on strong in the past few years.

Years ago the motors, batteries and radio gear were very heavy and the electric motors were fairly low in power.

Since then high power magnets, lighter & stronger batteries and flyweight radio gear have made electric flying practical. The biggest bonus is the noise reduction although you still have propeller noise.

Dan
 

·
Custom User Title
Joined
·
347 Posts
oh yes, i posted a few mouths ago about these my colection has grown from 3 to 7 and i actually got a few from some one from this thread which im thankful for. i have the diesel conversion for on of my cox it runs great as soon as you get the compression settings down
 

·
Registered
Joined
·
90 Posts
There are a few differences in running a diesel compared to glo.

The prop should be at least 1" greater in either pitch or diameter on a diesel as it has more power per drop than glo fuel.

Flip the prop a with a little more "Snap" than you would with a glo.

An easy way to find a needle setting for a starting poing is to put a piece of fuel line on the needle valve nipple and open the needle slowly whilst blowing air in the fuel line. Once you get a little air flow give it maybe 1/4 more turn open.

For compression, you only get one chance with some engines if you start with too high a setting. You can quickly bend a rod or break a crank pretty easily if you are heavy-handed.

Back off the compression to a very light setting and then prime. Flip a few times to see if it will pop. Be slow and deliberate as you only want to increase the compression a bit at a time until it starts to pop.

Don't worry about the needle valve until you find a good compression setting. A prime will let you know if it will start.

Once you get it running, warm the engine up for a while before resetting the compression. If you hear the engine laboring, back off on the screw until it sounds "Happy" and you should be good.

Make minor changes in needle and compression settings until you feel satisfied with the sound.
 
1 - 10 of 10 Posts
Top