Evolution of the Tee Dee 049

balogh Wed Mar 04, 2015 12:38 am

I have collected quite a number of Tee Dee 049/050/051-s over the last couple of years and noted the obvious evolution of e.g. the 049-s.

Pictured below are 2 beauties aka Twin Dee-s, pre 1972 design with the following differentiating features compared to later designs:

1. Venturi without the screen
2. No. 4 stamped cylinder, stepped wall, top fins without milling for the wrench - later designs from the 1980/90-s came with thick wall cylinder and top fin milled
3. Tapered cylinder/piston fit (later, stepped wall cylinders with the top fin milled are not all tapered)
3. Piston made of 2 parts (separate part for the balljoint cap) (later designs made from one piece)
3. Strange, whitish metal conrod, with oiling drill on the large end. (later conrods are the brownish, steel material, with no oiling drill at all)

Evolution of the Tee Dee 049 Twinde10

This oiling drill though was missing already on the one on the left side, even if the conrod material is the same white metal.
Evolution of the Tee Dee 049 Twinde11

We know COX notoriously interchanged various components in its engines depending on the component production run - never to the compromise of the quality, but making age identification sometimes a puzzle.

I mesured the crankpin hole diamater on this conrod with the oiling hole and on a later design conrod with no oiling hole in anticipation that with the oiling hole abandoned, the diameter of the conrod bottom end might be a bit larger in order to allow the oil to enter the journal bearing gap, but - at least with my calliper type gauge - I found both designs are 2,5mm in diamater.

So the ommission of the oiling drill was not followed by any dimension alteration in the conrod bottom end, in the obvious recognition that the oiling drill was just a cost adder but could be dispensed with without the compromise of the lubrication of the crankpin.

Sorry for the academic elaboration on this relatively simple topic, but those interested in the COX design evolution may find it useful.

Marleysky Wed Mar 04, 2015 10:54 am

No, no, no do not apologize:

" Sorry for the academic elaboration on this relatively simple topic, but those interested in the COX design evolution may find it useful."

We need all the information we can get, so we can be better informed on these engines we admire so much. I think you've done a good thing. I learned that there were oil holes in con rods, never knew that before. Thanks! Rene

KariFS Wed Mar 04, 2015 1:21 pm

Is the oil hole a "Tee Dee only" feature?

My Tee Dee has plain anodizing on the carb and drive plate instead of the gold color, anyone know when that was dropped? Mine is a thick-cylinder one so it's one of the later versions.

EDIT: BTW Balogh, have you checked if the one with the oil hole is magnetic or not, or compared the weights of the piston assemblies?

balogh Wed Mar 04, 2015 1:25 pm

I think ther oil hole was just an ill-fated feature used on TD049-s only. On the very early ones.

If you look at eBay some, but not all of the christal box TD-s (probably sold throught the 70-s) already come with the thick-wall cylinders, and those which are in the black/red cardboard boxes are all invariable thick wall cylinders. So these may be around since the late 70-s I guess.

balogh Wed Mar 04, 2015 1:41 pm

KariFS wrote:Is the oil hole a "Tee Dee only" feature?

My Tee Dee has plain anodizing on the carb and drive plate I nstead of the gold color, anyone know when that was dropped? Mine is a thick-cylinder one so it's one of the later versions.

EDIT: BTW Balogh, have you checked if the one with the oil hole is magnetic or not, or compared the weights of the piston assemblies?

Kari,

great idea...I checked and the conrod of the old TD made of the whitish metal is magnetic (just like that of the "modern piston/conrod combos) so this must me steel, of course. The one without the oil hole (but also whitish material) weighs 3,08 grams, while a "modern" piston/conrod combo weighs 3,21 grams....strange, maybe the piston wall thickness is larger in the "modern" combos?

1/2A Nut Wed Mar 04, 2015 2:53 pm

As large as the hole is I think a previous owner drilled it out. Balogh did you buy this new in the box at some point back in the day?

I have never seen a oil hole I have owned about 27 TD's over the years and have 14 on hand now spanning all the decades. A factory oil hole would be smaller in relation to size.

crankbndr Wed Mar 04, 2015 3:25 pm

A short thread on the oiling hole

https://www.coxengineforum.com/t5493-piston-type?highlight=piston+type

balogh Wed Mar 04, 2015 4:03 pm

1/2A Nut wrote:As large as the hole is I think a previous owner drilled it out. Balogh did you buy this new in the box at some point back in the day?

I have never seen a oil hole I have owned about 27 TD's over the years and have 14 on hand now spanning all the decades. A factory oil hole would be smaller in relation to size.

I also have more than 10 TD-s but this is the only one with the oil hole.This is a brand new never run TD with the oil hole on the conrod. It came from an eBay seller in the original chrystal box with papers, decals and wrenches. I do not think it was a home-made hole but must have been a limited edition of the earlier TD-s.

The thread above shows there must have been a short production run with the holes in the conrod as another piston and conrod combo was found to feature it..

Ken Cook Wed Mar 04, 2015 4:15 pm

I have a few of them with the holes. I don't feel it really offers any benefit to running them. I believe Cox felt the same way and decided to abandon it.