Td09 and medallion 09 differences

I'm assuming your engines have no plastic carb bodies on them? The TD carb body is threaded to accept the aluminum venturi stack. The Medallion versions had the venturi molded into the plastic body with the needle valve assembly passing through the middle whereas the TD had it's needle behind the venturi. You already stated that your one engine had the TD setup.  The venturi used a peripheral groove around it with 3 jet holes to allow the fuel to enter. Typically, Medallion drive washers are mill finish aluminum vs the gold anodized versions of the TD's.

      As Rod mentioned, the crankshaft has a small round hole for the Medallion and a larger rectangular hole for the TD's. TD.09's came equipped with spinners and Medallions had a aluminum prop washer. You should easily detect what Rod mentioned in regards to crank valve cutout with the bodies removed. You can see the shaft in the case.

As for glowheads, around the post of the plug the TD came equipped with a plug recognizeable by knurling 360 deg around the center post and the Medallion had no knurling.

Coxfledgling wrote:I have downloaded the spec sheets for both of these wonderfully engines, thanks so much CEF.
Looking at the specs both have the same bore and stroke but different part numbers for glow head, cylinder and piston, and crankcase.

I have been told that both my Cox 09's are TD's, but what are the easily seen outwardly differences of these engines if neither of mine have a carb manifold, the part held onto the front of the engine with the alloy slotted "tube nut" please. The carb  body ?

When I acquired these engines many years ago, one had no carb body at all and the other had a broken black plastic TD carb body, with the alloy Venturi and gold coloured needle valve holder/fuel reciever manifold.

What are the differences of the glow head, cylinder and crankcases please.

This is to make sure that both of my 09's are TD's before I order some parts for them.

All help greatly recieved, thanks.

Additionally to what the other posters have said regarding the TD vs Medallion. The TD should have a gold anodised prop driver, and be fitted with a thrust washer behind it-phenolic plastic if earlier, thin steel in later ones-the Medallion has a plain natural alloy coloured prop driver and usually no thrust washer (though it is a good idea to fit one if the opportunity presents!) To the best of my reasonably extensive Cox knowledge-there is NO difference in the crankcase or backplate in the two engine types. The std Medallion should have only a single transfer flute in the cylinder-the TD has two-but you may find the later R/C Medallions with the rotating barrel exhaust throttle have two transfers-these are in any case easily ID'd by the ground surface where the throttle fits on the outside of the cylinder. Finally-in addition to the knurling on the TD head, the underside of each is different-the TD has a high compression 'trumpet' shaped profile, the medallion head a hemispherical lower compression profile. Note that all parts readily interchange between TD and Medallion 09 variants-with the exception of the NVAs -so all sorts of intermediate hybrids can be produced. note also that some parts are virtually unobtainable-such as TD 09 venturis-these days, stocks of spares having been well exhausted-but demand not being high enough to justify Cox Intl to get a run of new aftermarket parts done-which would probably have a minimum run size of 1000 or 10000 units...

ChrisM
'ffkiwi'

Thanks guy's, I can now order with confidence but will check glow heads.

I need 2 carb bodies as one is broken, so I have a spare. I know of the alloy carb body version and will consider that part but there is no "stub" for tank pressurisation.

I will also get 2 glow heads, one as a spare.
I also know of the converted head and seperate glow plug, probably getting one of each, as a spare/standby.

But engine are identical from memory, but that was a good 20 years ago. I ran both up last year then covid hit.
The Venturi annular fuel holes where blocked and cleaned with solvent and ran great after, apart from the one with "something" intwined in the glow coil, which is gunna be difficult to clear due to the fragility of the glow coil.
Thanks again, brilliant forum.

The nipple on the side of the venturi body is for timed crank pressure. This requires the crankcase to be drilled to use it. I highly recommend that you don't consider this option. It's very problematic, if not 100% sealed it will cause very erratic runs. It's only required if one drills out the venturi for a very slight power gain. The larger venturi is now too big to draw fuel on it's own therefore requiring some pressure assistance.