I have a 1/2A scale project in mind that needs some creative thinking to be feasible. Is there a safe maximum distance between a tanks pickup and a TD's backplate? Getting the tank further back would help with the balance problem. An inch or two would be great if it doesn't kill fuel draw. Said tank would be @ 1/2-3/4 oz, shape undetermined yet. Would like to build the tanks uniflow plumbing on a small tin disc or wedge end, then construct the body and other end from a lightweight, easy to use material. (no user molded plastic, bladders or heavy materials.) Thinking an Estes rocket body tube an inch in dia with silkspanned ends. A few drops of epoxy to seal the innards. Found a weight spec for a Sullivans 1 oz tank at 1.4 oz weight. I think I can beat that.
30 years ago I built this project with an anemic .09, looked great, was very overweight and flew like a nose heavy brick on 42 ft lines.

I see you don't want to use a bladder (pressure) but floppy balloon tanks weigh just about nothing, feed fuel without a chance of foaming or bubbles and are cheap. Search this forum for information. 🤠

Thank you. I like the no pressure balloon concept. I have questions but I'll read up first to if they've already been answered

With the stock venturi, the TeeDee has marginal fuel draw.  But if you choke done the venturi a little you can get really good suction with a minimal, if any , power loss.  These planes had winning performance set up that way.   The twin had the engines out for PM in this pitcher.

Plug the spray holes with fine wire.  Fill with JB Weld, and redrill to a smaller size.

a Madalin plastic front end will give you a much steadier run with better suction

Still looking at all the options you guys are suggesting. Pulled the venturi out and the plastic body is history. Cracked in front from intake to collet nut and another near the mounting lugs on the case side. Will send an order to Cox int for both a td and medallion case then start reading up on glo heads. So much to learn...and relearn.
Question for Paul, Did you use old style rock hard JB weld, or the newer faster setting stuff that seems to have a bit of flexibility?

            Paul posted his technique on here a few years ago. One thing I've noticed is that the older thin wall cylinder style TD appearance wise looks to have a smaller inlet on the venturi. The newer thick walled cylinder is difficult to tell due to it having a screen over the intake whereas the older version didn't use a screen. The other issue is that if you own a engine with unknown history, someone could've drilled it out as well. I've done this quite a few times due to running them on bladders and if I decide to use it on suction, I forgot I drilled it out that is until the problems of running rise up.

At the time I just used the only JB available.  Since this was used as a choke with no stress, I don't think it matters.  In fact any glue or filler that's fuel proof would work.

The issue of a cracked or stripped plastic front end is a real issue.  Once one goes bad, the engine won't run.  So finding a new Cox part is the challenge. 

When running bladders, I was able to jury rig a remote NVA with a Medallion front end.  These worked great.  See?  The dump tube was allowed to be free-floating in the venuri, so there was no stress when the combat plane checked the turf.

A few years ago I developed my own technique for using bladder on a Medallion .049 engine.  You don't have to permanently modify the venturi body, so you can go back to the normal NVA if you want to later.  I also tried this technique with Medallion .09 and .15 engines and it works quite well, although you do need to use JB Weld for the .15 venturi body.  A description of what I did starts on post #29 of this thread: Medallion .049

And the .15 in this thread: Medallion .15

Mark