Cox Olympic Rear Drum Valve engine details. Now with Video!!!!

Good for you Jason. Thanks for that.

I ran the Olympic 15 reed valve engine today. The RPM is a lot higher probably because I did not have the valve timing set right on the rear drum valve engine.

Now you're cooking.

Nice working engine.

I have a question regarding the polished transfer ports of the cylinder. Does it really gives a better performance?
I have read (smattering) somewhere, that rough transfers would produce something like a lubricating film which increases the flow velocity

coxaddicted wrote:Nice working engine.

I have a question regarding the polished transfer ports of the cylinder. Does it really gives a better performance?
I have read (smattering) somewhere, that rough transfers would produce something like a lubricating film which increases the flow velocity

I bet you'll have a hard time getting people to agree on that. If I had to trust an opinion, I would ask our performance expert, Paul Gibeault. He doesn't post in the forums a lot, but if you shoot him a PM, I bet he'll give you a good answer. I haven't re-read his mouse racing article lately but I don't think he addressed that. It's a sticky at the top of the Cox Discussions forum, and on Bernie's site too.

.

Mudhen wrote:
Jason, that engine is, in the immortal words of Socrates, "Da Bomb!!!"
What an incredibly steady run!
Lates...Mud

BTW - Mine has rough ports.

Mud,

When are you going to run yours? I think I need to get my port timing set right for it to pick up some more RPM but may never run it again for fear of breaking the crank.

I don't think the polished ports are hurting performance any. The venturi intake is polished also. The rotary valve is almost razor sharp on the edge.

Jason

Jason. why the concern about the crank, do you think the drive pin is a weak link? Is that historically what fails on that engine?

Where are you going to find another one? All of the other parts with the exception of the rear drum valve and crank can be replaced with olympic reed valve parts.

Excellent !!! I kept forgetting to watch this video when I was out someplace that had a WiFi connection! Great Historic Stuff !!!!!!

Just a guess, but back in this engine's time speed flyers polished things for "better transfer flow"...whether it worked was iffy.

Perhaps this engine was once in the hands of a speed flyer who "breathed" on it to make it all it could be. Now lets suppose the Tee Dee came out, or one of the other greats of the day like K&B, Supertigre, etc. took the flyer's interest and the Olympic was "retired".

In any case, you have an excellent piece of history.

For some reason I have not been able to see the video, but I've heard it. :-) I'll eventually figure out what I'm doing wrong.

George

Here is the information I have on this engine from the ebay listing from the seller:

"I am selling off a very extensive model airplane collection for a friend. These are items from a life time of
collecting engines. This offering is a very rare, only one of twenty made, OLYMPIC ball bearing rear drum valve
glow speed engine. This engine was custom made by Bill Atwood, and given away at the 1960 Dallas Nats. This
engine is owned by "Doc" Richard Nichol, who was a young man flying speed at the 1960 Nats. He must have
made a good impression upon Bill Atwood, because he gave this engine to Doc to use and fly. Doc said he used
it briefly, but newer and faster engines soon surpassed it. He added it to his extensive model engine collection,
and it has been there collecting dust ever since. I will leave it to the new owner to clean. A very hard engine to
find, and a must have for the Cox engine collector."

Now if I could only confirm that "Doc" Richard Nichol actually participated in the 1960 Nats and if he placed.

Jason

Jason_WI wrote:[color=black]
This material will soften up in methanol so not too practical to use

Hey Jason,

Do you still have the mold of the prototype Olympic carb body?

Have you tried making duplicate carb bodies using different plastics?

Also, is the mold you made heat sensitive? I'm asking because you could take a new cox carb body from a Medallion, melt it at around 300 degrees F, and pour it into your mold.

The mold I have is only for composites. Delrin needs to be injected molded under heat and pressure.

I might be able to 3D print one out of zytel which is a form of nylon. I just need to model it up in CAD.

Thanks again for running that up. Very cool! I tried to give you a greenie, but apparently I already did!

This thread is SUCH a teaser now that the images/vids are gone... my inserted emoticons won't even show up..

The vids are still linked but I will need to add the pics back because I wasn't going to pay the photobucket ransom.