Its pretty important that you get a consistant run out of the tank , Im setting up a wedge type tank with the uniflow vent about half way , maybe a little bias towards the back of the tank , is this regarded as the best setup , I suppose so ?

I dont like to use a plastic tank with a moveable clunk in its ,its not quite vintage controline looking
I think one of the things that kills good tank feed to the engine is engine vibration

Great suggestions for getting the head bolt out; perhaps better that way than before I break it off. I'll try soaking with oil for awhile, more heat, soothing curses, and whatever it takes. Here are a few pictures of what I am using, and where the problem bolt is, right in front of the exhaust.

Talking about bushed rods only being on the more expensive engines, here's an old Enya .09, regular plain jane, no BB and no muffler. But, this engine does have a bushed lower end . The crank pin or the rod end is slightly bent and the engine binds when the front end screws are tightened up; left loose on the front end, no binding, so it doesn't take much.

Wedge fuel tank works best for U/C. I use to use two vents, each to the other side of the tank. I flew with the top vent capped off. Vibration caused foaming in a ridge tank. Balance the prop. A smaller venturi will improve fuel suction, or a small 1/8 th inch tube could be used to direct muffler pressure, but for a diesel that shouldn't be needed.

Try a thicker gasket on the front end, that may cure the bind when the bolts are tightened up.

I have yet to see a diesel run right on a glow carb, always has to do with fuel draw: the smaller the venturi, the better draw in my experience.

If one has access to a variety of metal tanks, the best fuel draw will come from a chicken-hopper tank. If you build your own, there will be no problem doing that. I, too, haven't had much success with plastic, clunk-type tanks...

Originally Posted by TLyttle

I have yet to see a diesel run right on a glow carb, always has to do with fuel draw: the smaller the venturi, the better draw in my experience...

This is very true.....and, provided that you don't chase for top rpm's, you'll be surprised just how small a venturi a diesel will accept, with improved fuel suction and throttling properties....
On some carbs, you could just restrict the max throttle opening to acheive this. However a "cleaner" way of doing it, would be to insert a restrictor bush into the throttle drum, or simply shift to a smaller carb.....at occations I have tried all three methods with good results.

A 5cc (.29) diesel will do fine on a .09 size (glow) carb, or even smaller....

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Originally Posted by TLyttle

If one has access to a variety of metal tanks, the best fuel draw will come from a chicken-hopper tank. If you build your own, there will be no problem doing that. I, too, haven't had much success with plastic, clunk-type tanks...

In order to keep it simple, I use to avoid clunks too....for smaller RC, I prefer to use varoius standard C/L tanks if possible, though I have also made several tanks by modifying Colman's Mustard tins, etc...
I normally put the end of the pickup tube at the "bottom/rear" of the tank....

This setup obviously doesn't allow any prolonged inverted flight, but that is really the only limitation...

We may also consider that diesels have a very low fuel consumption, i.e. there's no need for a particularily large tank....
(My 1cc M.E. Heron runs 6 minutes on 10cc fuel, at full rpm with a 7x4 Master Airscrew)

Originally Posted by JohnAV8R

Great suggestions for getting the head bolt out; perhaps better that way than before I break it off. I'll try soaking with oil for awhile, more heat, soothing curses, and whatever it takes. Here are a few pictures of what I am using, and where the problem bolt is, right in front of the exhaust.

You can buy an allen key that is high speed steel and has a largish handgrip, you choose a slightly larger size, eg , the next size up in imperial , then using an offhand grinder resharpen the hex to a taper that locks into your damaged screw head , I think that heat will help too , good luck

Hey Guys, Can anyone recommend a 2.5cc diesel for freeflight use. Robust, easy to handle and swing a big prop etc.........

Steve

Thinking of a new one...?...I would strongly consider a PAW 15 DS....good value/fun for money at GBP 52.00....plus all spares quickly available etc etc...
Check at http://www.eifflaender.com/ I would prefer this one before a Chinese diesel any day....

..or, among the "classics":
Should you find an AM25 (not AE), this would be a good choice...practical and virtually indestructable...or, should one of the old Webra diesels (any type) come your way...just grab it..!...They are all top quality...

...I stop here, allowing some space for more suggestions....

Steve,
Consider also the New Parra 2.5 :- http://www.clubtamaran.com/parramotorING.htm
for sports use with larger props the steel cylinder version would be fine. they quote APC 10x4 @ 10,300 RPM which isnt shabby, its a modern twin ballraced diesel with optional extras available - ie different venturies,R/C carby, combat or regular muffler, can also be used as glow with one of the optional glow heads.
Stewart

Gluehand and Stewart............. thanks for the suggestions. The Parra looks nice but the Paw should be good enough.

It's for a heavily built j60

Steve

John
In extremis you could drill a small pilot hole laterally through that exhaust port stanchion to access the naughty threads and free up the bolt, then maybe have to tap for a larger size bolt after disassembly; but it's fraught, innit?

On PAW's website they say that internal cleaning for carbon buildup should never be necessary, that these diesels are "self-cleaning". Yet they recommend Castor, and your experience would indicate that "crud" does indeed build up as a result (even if in storage). And he exclaimed, and rose up, and fled out of the land of the Castor-ites, unto the Valley of the Cinn-thettiks, and he saw that it was good.

"No matter how much care is taken, however, the dismantling of mated parts invariably results in some degree of re-mating and consequent wear, and it is therefore never advisable, and should be done only when absolutely necessary. NEVER dismantle an engine in order to "decarbonise" it. Excess carbon is ejected by the engine automatically as it accumulates. ". So, if it ain't the carbon, and it ain't an accumulated ether build-up, the crud is the Castor Oil. QED.

PS -I have several Enya 09's, plain venturi and RC, and I love 'em! If they convert well to diesel I'll have another evil project looming...

Originally Posted by TLyttle

I have yet to see a diesel run right on a glow carb, always has to do with fuel draw: the smaller the venturi, the better draw in my experience.

I used the carbs from a pair of old type Thunder Tiger 20s (the OS Max copy ones) in diesels. One on a Silver Swallow 2.5c in place of the supplied insert the other on a PAW 19 that had lost it's own carb due to it vibrating loose in flight. Both worked perfectly. Easy starting & good throttle response, the PAW was better than with the original crude effort supplied with the engine

JohnAV8R, I once had similar immovable head screws on a Merco 61. It had Phillips head screws that had been chewed up. I managed to loosen all but one of the long ones. So I ended up cutting it with a junior hacksaw blade between the cooling fins. This meant I was able to remove the cylinder & fins etc leaving the cut screw accessible to mole grips. It then came out quite easily. The next problem was that I had difficulty identifying & locating the right size replacement screws. In the end I drilled out the 6 existing holes, tapped them 4BA & used allan studs. I later discovered that the originals were 1/8" Whitworth.

Here is my latest Diesel project a small Flitestreak , a top plane to fly

Stegla, the Parra is a nice engine. Clipclop seems to think so too. Have a look at their web site. I got one and will add a few pictures later. Or, as Gluehand suggests, you can’t go wrong with the PAW .15.

Chas, that’s another good idea , but with my luck I’d probably drill into the bolt. Patmcc, cutting the bolt seems like the best idea. There’s little chance of slipping off the end of a drill bit or marking up the engine. Does anyone know what bolt thread and size this Merco is using?

NX-687, what engine do you have there? Perhaps clean it up a little and send in a few pictures. What does the U/C weigh?