Olympic .15 Disc Valve Engine?

Jason_WI Fri Jan 25, 2019 12:04 am

So I won this on eBay a few days ago. I have an addiction.....

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F264133758438

It has a disc valve and a drum valve as part of the timing mechanisms. I have never seen mention of a disc valve Olympic engine. I’m thinking this was made by someone other than Cox.

The rear drum valve is included. It looks to be authentic but there are differences in the drum.

Here are the comparisons between drum valve assemblies. The broken carb body and the drum valve with the thicker wall is the new one.

Now the concerning part of this purchase. The crank pin on this engine looks to have been pressed in but the diameter is too small to drive the drum valve.

M

Here are pictures of my other drum valve engine crank pin. It is part of the crankshaft like the RR-1 crank.

I asked the seller for more history on this engine. The crank pin is concerning enough. I seem to be attracted like a moth to a light to fake engines like the fake Strato Bug a few years ago I had to send back to a seller on eBay.

**Cribbs74** Fri Jan 25, 2019 12:23 am

Interesting Jason, who on this forum could provide an answer? Mudhen?

You either have something rare or something home made. Hopefully the former. Did the seller ever respond?

crankbndr Fri Jan 25, 2019 6:45 am

One sure thing, eBay will side with you no matter what if you send it back and you will get your money back.

getback Fri Jan 25, 2019 7:15 am

Is that a spot weld in the second pic , one of intake ? i know what you were probably thinking on the plastic replacement but as you said the pin is a problem . You can clearly see it in your pics. And what the heck camera are you using to get souck detail pictures ? Very Happy

crankbndr Fri Jan 25, 2019 7:39 am

I wonder where the white plastic parts came from?

**Cribbs74** Fri Jan 25, 2019 8:07 am

So you have to think, Getting the olympic was easy, but re-creating the drum valves and the plastic housing isn’t. You would almost have to think that at least some of the parts are genuine

gkamysz Fri Jan 25, 2019 8:17 am

How do you prove this was or wasn't a prototype vs. the brainchild of a garage engineer? If this was an early prototype and the cranks with the drive pin weren't ready, it would make sense a smaller pin was pressed in to do some testing. Drilling a hole as large as the designed pin would weaken the crankpin excessively. The disc drive pin and disc looks pretty crude for a factory item, but so does that RR-2 beam mount prototype. I guess a careful machinist would have done a nicer job. Bill Hughes is well known, I doubt he's trying to pull anything. Hopefully there is some history available.

Jason_WI Fri Jan 25, 2019 8:58 am

Here is what I got back from the seller:

“Hi, This engine was part of the Glenn Lee estate. I have been asked to sell some of his old equipment to help pay for some of his health care costs. He is 87 and is now in a memory care facility. In case you do not know, Glenn Lee was a 2x USA F2A Speed Team Member in the 1960/70. He was 3rd in the 1964 World Championship in Hungary. He is one of the Legends of CL Speed in the USA.”

So it makes sense as to why the fins were cut down to probably to streamline the engine. The disc valve looks like it was used as the aluminum behind the plastic valve is a mirror finish polish.

I believe the drum valve portion is real. The disc valve was probably made by Glenn. Maybe something happened to the crank pin and a new one was pressed in. When pushing to the extreme things happen.

Jason_WI Fri Jan 25, 2019 9:56 pm

getback wrote: And what the heck camera are you using to get souck detail pictures ?

Boom mounted microscope with fiber optic light source. Picked out of the trash at work. I use my iPhone 8 through the eyepiece. Gets good detail. I took off the .5x lens to get more magnification. Comes in handy to remove burrs from cylinders.

Jason_WI Sat Jan 26, 2019 1:11 am

Working on drawing up the carb body for the drum valve. Hopefully print it out in nylon tomorrow.

balogh Sat Jan 26, 2019 6:26 am

Jason_WI wrote:Here is what I got back from the seller:

“Hi, This engine was part of the Glenn Lee estate. I have been asked to sell some of his old equipment to help pay for some of his health care costs. He is 87 and is now in a memory care facility. In case you do not know, Glenn Lee was a 2x USA F2A Speed Team Member in the 1960/70. He was 3rd in the 1964 World Championship in Hungary. He is one of the Legends of CL Speed in the USA.

Having read the above I (a Hungarian) searched the net for that 1964 event here and found that the Championship was held on July 29th 1964 with Bill Wisniewski of USA ending in 1st place with a speed of 227 km/ h, the 2nd was a famous Hungarian Gyula Krizsma with a speed of 225 km/h and Glenn Lee the 3rd at 223 km/h...pretty high speeds. The Hungarian Krizsma probably raced with a famous MOKI engine that he himself designed and manufactured...Glorious times of aeromodeling..

Jason_WI Sun Jan 27, 2019 12:12 am

Thanks for the confirmation of how he placed in '64 in the CL speed event.

Olympic carb body all drawn up and on the printer now.

Jason_WI Sun Jan 27, 2019 12:26 am

Hot off the printer. Need to shorten the neck a bit and I should be all good. This is clear PETG. Next ones will be nylon.

**Admin** Sun Jan 27, 2019 12:37 am

Looks good! Popcorn

getback Sun Jan 27, 2019 7:26 am

You got me wanting a cnc printer !! Nice !! Small Cox Logo

**Cribbs74** Sun Jan 27, 2019 11:34 am

Are you going to do them in Nylon? They look awesome. Too bad you didn’t have that printer when you were fixing my TD .15 carb body. It would have been a lot less work!

Edit: I guess I need to work on reading comprehension... I didn’t see you already plan on doing thrm in Nylon.

NEW222 Sun Jan 27, 2019 12:47 pm

Very nice work with the 3d printer.

Jason_WI Sun Jan 27, 2019 4:54 pm

Here is the carb body in zytel from DuPont.

Mudhen Sun Jan 27, 2019 5:25 pm

ffkiwi Mon Jan 28, 2019 6:41 pm

The drum valve is certainly genuine-there were a small number of factory produced drum valve derivatives of the Olympic produced ca 1959-60-rumoured to be a total of 50-by Bill Atwood-which were passed out to various people for testing and evaluation-at least one was used at the 1960 FF World Champs.....this was part of the R&D which lead directly to the TD series
....as for the disc valve unit-the workmanship is poor enough to convince me that this is NOT a factory job....
...as for the drive pin holes-well if you're starting off with standard Olympic components it is a lot easier to drill the crankpin for an insert extra pin than machine up, harden and grind a completely new crankshaft-and was well-there is ample precedent for rear disc drum engines using a drive pin of this 'press in' or 'plug in' nature simply for reasons of production economy-the Webra Mach-1, the Taifun Meteor-both 2.5cc BB rear disc engines-use this approach.

ChrisM
'ffkiwi'

Jason_WI Mon Jan 28, 2019 7:15 pm

When attempting to fit the drum valve back half to the crankcase with the modified crankshaft there is interference when the drum valve is tightened up. The crank pin is too long. So this crankshaft was specifically modified for the disc valve rear section as it fits without any interference.

I would like to run the disc valve engine but need to figure out a spray bar and needle valve to use. The venturi opening on the rear is threaded on each side. Not sure if that held in place another insert with spraybar mounted into that. The opening is pretty small so what ever it may have been would need to be thin.

ffkiwi Mon Jan 28, 2019 7:38 pm

Try a K&B racing NVA-the 7738 one-that screws into each side...an 8-32 or 10-32 thread if memory serves-and is a surface jet type-ie no spraybar-the jet is on one side the the venturi and only the needle itself projects into the venturi... ie the type used in the K&B 3.5 and the 4.9, and 6.5 FF/CL K&B FR engines of the 80s...

ChrisM
'ffkiwi'

Jason_WI Mon Jan 28, 2019 8:28 pm

Thanks for the tip on the 7738 NVA. That rear disc assembly looks like it was made to use this.

ffkiwi Mon Jan 28, 2019 8:38 pm

That's the one alright-as soon as I saw the tapped holes in your rear disc backplate assembly venturi I thought 'aha-K&B racing NVA...'.....and I omitted to mention earlier-also fitted as standard to the rear drum K&B 15 schneurle series 72 non R/C version....

ChrisM

Jason_WI Wed Jan 30, 2019 12:26 am

3/8-32 tap and die set came in. Venturi installed. Too bad it’s not the correct venturi. This is one for a TD .15.

The one used on the drum valve engines was bowl shaped vs the trumpet shaped shown here.

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