AMB

Looks like history repeats itself , Davis is going to make the .020 diesel head again for the Cox it has a good strong crank no issues on conversion
regards martin

nitroairplane

That is good news for me as it means he will be making spare teflon countergaskets maybe if i get another one of his diesel heads i will try it on a tee dee .020 as my pee wee .020 ran great here is a video of it.
http://www.youtube.com/watch?v=lT-2U7rHd50

Mr Cox

They run better on metal (brass) gaskets, I could never get the teflon to seal without pinching it off when tightening the head.

nitroairplane

The teflon is not ideal i admit but i think i will try and modify the head slightly to take an O ring like the MECOA ones use and like the .010 head AndyW made,

Miniature Aircraft Factory

For the seal in my diesel peewee ijust used a bit of coke can cut out with scissors, mine was converted using the article in Aeromodeller,before i had a lathe it was doneusing no tools other than ahacksaw , electric hand drill and a scalpel to bore the head out

It worked, but would have been easier to buy one

nitroairplane

MAF do you have the article still?

Miniature Aircraft Factory

I have it somewhere , everything is in boxes as im moving housein the next few months so i havepackedsome of the junk, ive been looking for it and cant find it ( should have labled the boxes), if i find it i can send it to you.

It was in Aeromodeller and was called ( i think ) `Of diaphrams and Diesels` , in the 1980s , i wassure it was1982 ( but could have been any year in the 80s ), weconverted a few enginesafter reading the article of both the 020 and 049

Ive had a look at this index of Aeromodeller magshttp://www.colinusher.info/Model%20A...romodeller.xlsand i cant find it, but i dont know how to search in the program it loads into

nitroairplane

Thank you but dont worry if you cant find it.

forsakenrider

wow very cool. would this be ok for a first diesel? I really dont want anything larger and would love to try diesel...

AMB

I would suggest the Cox 049 as a first readily available and lots of them out there, run on glow first to get the feel then put the diesel head on
the teflon disc on the davis head is the safety valve if overcompressed or hydrolocked it will blow only takes a minute to change it out and no engine damage I just got into the coxs thru the suggestion of Bob Davis my Medalion 049 runs like a swiss watch with his head before this into 09s to 60s mostly diesel and Davis conversions
all in rc planes the cox is slated for a little control line a step back to my high school days in the 50"s martin

Note a lot of the guys who have done this for a long tlme have the Cox 020 and asked Davis to reissue the head it has not been around for quite a few years the 049-051 conversion head has been in production about 35 years

Mr Cox

I have used aluminium foil from a soda can too, but the lifespan was quite short, less than ten tanks. With a slightly thicker brass foil I've done 10+ flight and it hasen't broken yet.

The DDD head I have for the .020 was too high in compression even at its lowest setting, and I've turned down the length of the counter piston to be able to reduce the compression enough. I don't know if this is a general problem with the DDD heads, but it is important to be able to reduce the compression in order to not break the crank pin.

With a well fitted and tight piston/cylinder combo these are very easy to hand start. It just needs a little prime on the side of the piston and it fires everytime.
Another advantage is that it is much less sensitive to the needle setting compared to when it is run on glow fuel. On glow the tank heats up during the run and it would rarely empty the tank, while on diesel it runs full tank everytime even if the needle would a little off.

Here is a short video of mine on the bench spinning a 6x3 prop at about 9500rpm:

[youtube]http://www.youtube.com/watch?v=mMJlI0rgXVo&feature=mfu_in_order&list=UL[/youtube]

nitroairplane

What Mr Cox said is all true and the pee wee .020 was actually my first diesel now i rarely run glow apart from my cox .010.
Mr.cox helped me get started on diesel and gave me advice an how not to break a crankpin. and advice on fuel but it was surprisingly easy but I a had quite a lot of experience on glow engines and cox engines before this but i would say it is fine to start with one of these.

Miniature Aircraft Factory

Is the TD 020s crankstrong enough to run one?

AMB

Crank is fine as I stated Davis made these 020 heads for cox years ago and no issues, the 049 reed valves had issues with cranks and Davis made a strong crank "killer crank" (still does) martin

66Malibu

I bought a Cox junk box from a closing hobby shop a while back and found a DDD .020 diesel conversion head in the bottom of the box. The LHS guy said look some more and you'll find a Pee Wee crank with the crank pin broken off there too. Obvisiously, there must have been a serious over compression isssue so I never tried it on a Pee Wee. Once I called DDD on the phone and he said the head must be used on Pee Wee's only and never on TD's !!! At that point I didn't care to blow up some good Pee Wee's so the unit has never been used by me. I keep it as an oddity......

forsakenrider

Anyone know when these are coming out? Im itching to get one!

fiery

My Feedback: (2)

Plus 1 ...

qazimoto

My Feedback: (1)

Here's the Aeromodeller article on converting the Cox 020 to diesel. The people who have done it suggest that it's completely satisfactory and good value considering how much it costs to do.

Ray

nitroairplane

thank god i have been looking for that diagram for ages but i think i would make it with an "o" ring on the contra and no counter gasket.

Mr Cox

The diagramme is the basically the davis diesel product to me.

fiery

My Feedback: (2)

The Pee Wee I have came from an estate and is in very good order. It has been run, but only a little.

It came in a plain box with three spare glow heads and two graupner grey 5x2 props.

My question: are these props a good match for the engine?

I compared it to a "Black Widow" 049 I also received, this thing half the size; by far the smallest engine I have ever seen. I have never had any exposure to Cox's before.

qazimoto

My Feedback: (1)

Yep they should be fine for your 020.

I have a few 020's down the shed left over from the 1960's. The trouble is that even in glow form they're fiddly. Rather than bother dieselizing them I'd much rather use a proper purpose built diesel like a DC Dart or it's modern replacement, a PAW .55. These are far more reliable.

The Coxes must have a really good p/l fit to make a decent diesel (as has been described on another forum) and it's potluck finding this.

Ray

Mr Cox

The major problem I've had with the PeeWee is that the tank heats up while running and this alters the needle optimum needle setting. It is therefore hard to get a good run throughout a whole tank. This improves a lot on diesel as they rarely quit, even if settings are not ideal, and it then at least empties the tank everytime.