Got it!............... :)

Warmed Hoppes hey? Never heard of that before. I have not even tried Hoppes as it is straight out of the bottle, but I have heard a lot about it.

And Cribbs..... Are you saying to use 1000+ grit sandpaper on the outside of the piston, and inside the cylinder? I thought of that before, but decided against it. Once in the past, myself, I put a piston/cylinder assembly on the crankcase then chucked up the prop screw in my drill. I then placed a tiny bit of ultra fine polish on the sides of the piston through the exhaust, and a tiny bit on top. Ran it for a minute, then flushed it out. I repeated the process again with toothpase and rinsed again. The engine is now a strong runner. Just something I had done, as there is no wrong or right, but rather 'many ways to skin a cat'.

That is the worst case that I ever seen ! I would put a new crank in it , that crank has seen better days . Can't wait to see this one run again .

Mike1484

NEW222 wrote:Warmed Hoppes hey? Never heard of that before. I have not even tried Hoppes as it is straight out of the bottle, but I have heard a lot about it.

And Cribbs..... Are you saying to use 1000+ grit sandpaper on the outside of the piston, and inside the cylinder? I thought of that before, but decided against it. Once in the past, myself, I put a piston/cylinder assembly on the crankcase then chucked up the prop screw in my drill. I then placed a tiny bit of ultra fine polish on the sides of the piston through the exhaust, and a tiny bit on top. Ran it for a minute, then flushed it out. I repeated the process again with toothpase and rinsed again. The engine is now a strong runner. Just something I had done, as there is no wrong or right, but rather 'many ways to skin a cat'.

Your way is fine. Nothing wrong with that. Yes I have used in the past some very fine grade sandpaper to clean up pistons and cylinders. I may be wrong on the 1000+ but It should feel like thick regular paper on your fingers.

Cool stuff happening here.. but I believe that the diesel-head hasn't been removed from the .051 cylinder yet.. (correct?) I'm really glad that the piston came out of the jug. I don't recall the particulars involved.. but if the rod looks ok.. it would be worth the time to re-check/fit the piston to the cylinder.. reset the socket-joint etc.

I have a notion that the diesel-head is something that you'll want to use. If the compression-screw turns; you may not have to remove the head.. (if it was stuck..)

Kudos on the brute-force removal of the backplate.. you got it..

Sorry I forgot to add in my earlier post that I'm glad you got it out!

Well I'll be, good job, Bob, anticipate seeing the good in 3 runners returning to service.

Way to go Bob! Proof that it's not the destination, it's the journey.

Quite a transformation, Bob, congrats, you turned rotten apples into good apple sauce. I wonder how the Tee Dee crank will perform in the Medallion venturi setup, probably have generously decent performance.

rsv1cox wrote:

GallopingGhostler wrote:Quite a transformation, Bob, congrats, you turned rotten apples into good apple sauce. I wonder how the Tee Dee crank will perform in the Medallion venturi setup, probably have generously decent performance.

I'm not sure George, all crank shafts were returned to the original cases. I kept all three engine parts separate from one another. The Medallion has a different cylinder than the TD. The Medallion cylinder had only one booster per intake, while the TD had two.

Bob, I was just a little curious. I've got a .049 Medallion, still planning to convert to RC with a kit from Cox International. It's a dual bypass non-SPI double slit cylinder set with a rotating exhaust muffler ring. My suspicions is that with non-SPI dual bypasses will provide better power than the original SPI single bypass especially when muffled. Since it has the R/C Bee style silicon muffler cover for muffling, can be easily tried with and without muffling.

I just need to find where I put my engine test stand. It got set aside when I was working on other projects like repairing and modifying Salvation Army Kettle Stands (built new wood frame wind resistant sign stands for them), painting and decorating 55 gallon drums for Christmas food and toy donations, motorcycle and house maintenance repairs.

This is something I have been planning to do because of suction problems with a TD. My honest opinion is I don’t think the crank will bring a lot to the party. The Medallion draws fuel well and is a top notch sport engine. Remember the baby clown George?

The Medallion venturi will choke it down on the intake side so any benefit the crank provides on the fuel draw will be somewhat negated.

There is a fudge factor and perhaps the crank opening will allow more air into the equation.

The Medallion engine by itself is a very good performer and with a number one or number four cylinder will really wake the engine up for plenty of fun.

Ron

The crank dimensions are slightly different between the Tee Dee and Medallion too.  The Tee Dee crankshaft is about a millimeter shorter, measured from the nose to the face of the web due to the extra thickness of the web.  I bought some Medallions with the intention of converting them to Tee Dees.  No dice.  The drive plate binds on the front of the case with the Tee Dee crankshaft.  

I haven't tried it yet but I'll bet that a #4 on a Medallion would run pretty strong and still maintain the easygoing Medallion personality.  It might want an extra head gasket or two though.

Here's a picture of the two different cases, side by side.



You can see that the length of the bearing face is slightly longer on the Medallion case on the top.

Looking forward to hearing about how they run. Really nice work Bob.

Bob, what you see is the reason there is a #2 on the case.

There is a crank difference between the two cases. As alluded to by another post.

I must now ask. What did you do, or use on the crankshafts? Moreso, I have cleaned a couple up previously, but I am reffering to the very back side with the pin that attaches to the connecting rod. When I got to that part I just lubed it up good and called it just that. Good! Yours look just like factory. Thank you.

Cribbs74 wrote:This is something I have been planning to do because of suction problems with a TD. My honest opinion is I don’t think the crank will bring a lot to the party. The Medallion draws fuel well and is a top notch sport engine. Remember the baby clown George?

The Medallion venturi will choke it down on the intake side so any benefit the crank provides on the fuel draw will be somewhat negated. There is a fudge factor and perhaps the crank opening will allow more air into the equation. The Medallion engine by itself is a very good performer and with a number one or number four cylinder will really wake the engine up for plenty of fun.

Ron, I looked at how wide the Tee Dee's crankshaft rectangular intake valve opening is to the Medallion's. Yes, there is more restriction to the Medallion venturi. This gives it better suction feed. However, the Tee Dee then basically gives it no airflow resistance versus some resistance with the Medallion.

It won't be an earth shattering amount, but I believe that there will be some advantage to it, may be say a hundred to several hundred RPM difference. The improvement might be more noticeable when using a non-SPI cylinder set.

The Medallion was purposely downscoped in power by Cox by using the single bypass Babe Bee cylinder-piston set. It is cheaper to mill a round hole in the crankshaft than the rectangular one in the Tee Dee. The front rotary valve design was more free flowing than with the reedies. The hole and crankcase hollow shaft passageway are larger than the reedies. Thus the air-fuel mixture is denser to start, boosted further by SPI.

With the Medallion hole design, the passageway size will vary due to the round hole forming the intake valve action. Greatest intake flow occurs when the hole is immediately below the venturi. With the Tee Dee, as soon as the crankshaft rectangular valve face hits the venturi area, you immediately have more open area versus a sliver of the round hole in the Medallion. Suction is immediate and thus more air-fuel is drawn, giving a greater volume through the valve opening cycle.

I think there will be a boost. It won't be huge, but enough to improve the Medallion's run to put a smile on someone's face. Perhaps one day someone will post their RPM results to give us a heads up on the extent of improvement.

And, I do intend to check how my Medallion .049 performs, first with its earlier Babe Bee single bypass with SPI cylinder-piston to the double bypass without SPI cylinder-piston set with throttle muffler, since I have have a tach.    

Just a little busy now with the Salvation Army's Christmas activities.

Good Job !! I just got around to reading this and the engines came out really nice > getting 3 TD / medallion engines for that price is the way i like to deal . A little work can make a big difference in these engines , Bee watching for the report on how they run but am sure they will bee good . If you haven't ran one before your in for some real fun!! Stick one those 4" props on there and let it turn up

rsv1cox wrote:
Does that compression piston just drive out with a drift?
Bob

Just use the compression screw to drive the contra-piston out- save maybe damaging the thread with a drift.
These type heads probably dont have a super-tight fit as they use an o-ring to seal rather than a machine-fit like "real" diesels. Shouldn't be hard to find a replacement o-ring. Auto parts shop would be best rather than a hardware store.