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Engine basics => Engine set up tips => Topic started by: Frank Sheridan on May 14, 2009, 05:40:37 PM

Title: Cox reed valve restoration
Post by: Frank Sheridan on May 14, 2009, 05:40:37 PM

Hello all, I picked up some used Cox .049 engine parts on eBay to get the Beryllium Copper reeds which are no longer in production due to their hazardous qualities. Some are a little distorted and I was wondering if anyone knows a trick to flattening them back out without damaging them.

Title: Re: Cox reed valve restoration
Post by: ray copeland on May 14, 2009, 08:26:50 PM

Frank, i think there is no real easy way to flatten those reeds, i would suggest run it one way for a while then turn it over, that is what i used to do with copper reeds. You can also try the teflon reeds from someone like Davis Diesel, they just need a little time to break them in from my experience..   

Title: Re: Cox reed valve restoration
Post by: john e. holliday on May 19, 2009, 11:58:35 AM

As stated the Teflon reeds are the way to go.  It does take a run or two to seat them in.  DOC Holliday

Title: Re: Cox reed valve restoration
Post by: Mark Misegadis on July 21, 2009, 10:57:58 AM

Hi, Question on the Teflon reeds. I read above that they are the way to go. Why is that? Any of the new motors that I have do not run as hard as older motors with a copper reed.

Does this work the same for everyone else?

Now I dont have Davis reeds but the stock clear plastic ones that I assumed were made from Lexan.

Mark

Title: Re: Cox reed valve restoration
Post by: Frank Sheridan on July 23, 2009, 07:32:12 PM

The clear reeds that come on the new engines are made of Mylar. They seem to work as well as the old beryllium copper ones but with time the residual heat in the crankcase will affect them. Teflon takes the heat better. I haven't tried the stainless reeds so I can't say anything about them. You can buy a sample pack of the different types of reeds at http://coxengines.ca/

Title: Re: Cox reed valve restoration
Post by: Larry Renger on July 23, 2009, 11:20:26 PM

IMHO, having instigated the stainless reed, it is the best.  The performance is excellent, and I have yet to see one fail in any way.  Mylar was an excellent choice for the RTF planes, if it started and got one flight, it was golden!  After about 10 runs, the performance went to pot.  Bronze reeds, as noted, work harden and eventually, I have even seen the center disc fall out!  We used the stainless reeds on the Killer Bee and Venom, both running over 20K.

Title: Re: Cox reed valve restoration
Post by: Frank Sheridan on July 25, 2009, 02:54:11 PM

Nothing quite sounds like a Cox at 20K rpm.

Title: Re: Cox reed valve restoration
Post by: Larry Renger on July 27, 2009, 12:18:18 PM

Oh, I don't know, an AP Wasp at 22K is kind of sweet!

Title: Re: Cox reed valve restoration
Post by: Stan Tyler on July 27, 2009, 01:29:05 PM

I kind of like the sound of two TDs singing in harmony!  A few discords is OK too.