hole thru Tee Dee .020 Venturi nipple area and thru right side of TD crankcase

Cribbs74 wrote:It was drilled for crankcase pressure. It’s needs to be filled for it to run properly, unless you use it to pressurize a fuel tank.

   What can I use to fill the hole in the crankcase?
   The original owner says he remembers racing with a quickie 200 with a Cox .049, doesn’t remember racing with a TD ..020.
I was thinking of reselling it and offering an additional new Venturi.
   I replaced the Venturi, do you think it will run o.k. or will the pressure leak thru the hole and around the Venturi?

Thanks for the hints.   Happydad    

dad.

I have an idea that it is there to ensure that at the very high RPM of a Tee Dee the crankcase is at atmospheric pressure to enable better filling during induction.

By the time that the cut out in the crank starts to open that small hole the piston will be at BDC.
Now. The fuel air mixture is quite dense and getting it all to travel through the transfer ports will take a finite length of time and at very high revs there may not be enough time to transfer all of the fuel leaving some pressurised fuel under the piston.

That little hole will mean that the system is at atmospheric pressure ready for induction.

It's just a guess and I am probably wrong!?
Cribbs, who has a younger a thus wiser brain than I, is probably 100% correct!
Dave.

The hole must be filled for it to run properly. Even with pressure, it becomes so problematic it's not worth using. It really requires the use of a one way valve like Fourmost used to produce. I've purchased 1/16" aluminum dowel rod and re drilled the hole. I use JB weld as adhesive. Drill the hole with a #53 bit for a interference fit and it need be you can file a slight taper on the dowel rod.

happydad wrote:
I was thinking of reselling it and offering an additional new Venturi.
   I replaced the Venturi, do you think it will run o.k. or will the pressure leak thru the hole and around the Venturi?

Thanks for the hints.   Happydad    

Do you mean carburetor body?

https://www.ebay.com/itm/Cox-020-Tee-Dee-Airplane-Engine-Carburetor-Carb-Body-020-/282104214204?hash=item41aeb8b2bc

I think that a little RTV silicone around the crankcase fills the hole, then a new carb body do the work.

Here is a snapshot of the TD .010/.020 instruction sheet found in this forum. It explains what is going on with your engine. I have only filled a couple holes and I used JB weld and it has held for a long time.

Cribbs74 wrote:Here is a snapshot of the TD .010/.020 instruction sheet found in this forum. It explains what is going on with your engine. I have only filled a couple holes and I used JB weld and it has held for a long time.

It is so beautiful. The gold and silver, maybe nickel coating, that I hate to change anything. Thanks Ron.

Happydad.        

Levent Suberk wrote:

happydad wrote:
I was thinking of reselling it and offering an additional new Venturi.
   I replaced the Venturi, do you think it will run o.k. or will the pressure leak thru the hole and around the Venturi?

Thanks for the hints.   Happydad    

Do you mean carburetor body?

https://www.ebay.com/itm/Cox-020-Tee-Dee-Airplane-Engine-Carburetor-Carb-Body-020-/282104214204?hash=item41aeb8b2bc

No the entire engine. I buy, refurbish, resell. I always completely disassemble the engine, clean with fuel and old tooth brush, replace old gaskets, tubing, Venturi with hole in nipple then run the engine.
I haven’t had a chance to run yet. Just got the engine yesterday.
   Also got 4 brand new in package .020 engine wrench’s late last night. Email said they were delivered, but I didn’t get them with the engine at 1:30 pM. So I went out late last night and there they were.

More later. Gotta go.  Happydad        

You may get lucky without filling the hole and hoping the carb body seals well enough. The hole being there changes the crankcase pressure and volume. I have seen first hand some engines with that hole not even start until it was filled back in and some run just fine with the hole open. Personally I would fill the hole. It only takes a tiny amount of JB to do it and is completely hidden once you put the carb body back on. Might as well mess with it once and be done with it. It will save you from having to pull it apart again if it doesn’t work.

BTW all the gold/silver you see is just dye and anodizing. The aluminum is just clean and bright before it was anodized.

Cribbs74 wrote:You may get lucky without filling the hole and hoping the carb body seals well enough. The hole being there changes the crankcase pressure and volume. I have seen first hand some engines with that hole not even start until it was filled back in and some run just fine with the hole open. Personally I would fill the hole. It only takes a tiny amount of JB to do it and is completely hidden once you put the carb body back on. Might as well mess with it once and be done with it. It will save you from having to pull it apart again if it doesn’t work.

BTW all the gold/silver you see is just dye and anodizing. The aluminum is just clean and bright before it was anodized.

Cribbs74: you may not believe this, but another Tee Dee .020 with the tinned, anodized, whatever, silvered looking crankshaft area inside Tee Dee .020 crankcase AND the Venturi base, red thing, totally melted.

   Pictures tomorrow.

>>>>edited on 9-22-2020 at 6:15p.m. PST.  
Cox TD.020 #3

Sold as Lightly used? Venturi broken burned.

Tee Dee #4

Another broken Venturi.

Tee Dee #4

What is the "Silver Lining" for?

>>>>edit complete

Happydad