Is hotter fuel harder to needle?

Tee Dees love 35% and you will too!

It's probably because he was running a lot of compression and never added a gasket when he went to the higher nitro.

Fire up a engine with 35% and get a reading, notice how the needle valve responses, add a gasket and check again.

35% should get you quicker starts, more RPM, and easy to needle, but you need the right compression.

Or else things can go wrong.

I have an old peewee 020 that doesn`t like to hold a needle setting or rev all the way up to peak rpm without a gasket or 2 in there even with the stock low compression 020 glow head on it.

Keep tinkering with it until you get it.

Great. I thought so and that's what I was hoping for for my Black Widows too. Since I like to use a 6" prop for stunting they are just slightly underpowered when I get wild and I was hoping to pump some extra go out of them too. They love a 5" prop but I can't loop worth a damn with those.

I can't wait to try it in the TD. I just rebuilt it. It needed de-varnishing pretty bad. There was one spot at the top of the bore I never could clean, but I'll run it in rich and take it out and turn it loose this weekend.

Normally this de-varnishes nicely, just be careful which ones you use, some are too agressive to use on plastics or even copper.
Some can totally disolve copper head gaskets ....but the bore is clean

Sometimes an imposible steady needle setting is due to a bad needle too, or a dirty engine,or a mfg defect, but you knew that

Jaspur_x wrote:Normally this de-varnishes nicely, just be careful which ones you use, some are too agressive to use on plastics or even copper.
Some can totally disolve copper head gaskets ....but the bore is clean

Sometimes an imposible steady needle setting is due to a bad needle too, or a dirty engine,or a mfg defect, but you knew that

I just used denatured alcohol and a scotchbrite pad. I was pretty gentle with it, but I did rub harder on that stubborn spot that never went completely away.

If you are running all-castor lube, switching to lube with some synthetic will clean it up a bit. Some run 50/50 castor synthetic to keep it clean.

George

Edit: From my experience, it needled OK at 5% but needled better at 10% and above. Another factor that can affect needleing is that when the engine is "over the hill" it sometimes gets harder to needle because peak gets wider and you may run a little rich or a little lean. Increasing nitro may lessen this effect...I never tried it.

I switched to SIG 25%-50/50 Klotz/castor soon after getting the engine. At first I used GlowplugBoy 24%-100% castor, but only for a few runs. I think it was varnished before I got it. I took it apart and cleaned it before running it, but I did not devarnish it like I probably I should have.

Varnish on the piston/cylinder will reappear, it’s just a matter of time.

It depends on how lean (hot) its ran and percent of caster used.

The synthetic scrub (scotch bite) pad works great, in the ‘olden’ days ‘000’ steel wool was the choice.

Is it unusual to have to rotate the piston in search of the loosest glide up the bore, or is this an indication it's worn out? In some positions it tightened 3/4 of the way up, and I was able to find a position where it made it almost to the head deck before it tightened. I tried my best to get it all back together in that position. As a tapered #4 set is supposed to be, it won't go all the way through.
Like I mentioned above, it may find the sweet spot by itself, but I'm going to give it a couple of rich runs before I let it rip.

It's on the test block tonight, so I'm going to have it ready to fly tomorrow, in case I get a chance. My 35% SIG fuel came today.

Thanks,
Rusty

I didn't have the great time testing my new SIG 35% that I expected. It was 7PM before I could get to the workshop. I used last weekend's pressure bladder and cranked the TD and ran one rich run. Then I fired it up again full speed and it ran fine and faster than it did on the 24%. Kind of a pain to get cranked but not that bad. After that, all it would do is sputter and flood over and over. So I tried a Bee head and it was worse. Tried more and less gaskets. Put the Gallbreath back on it and wasted 60cc of new fuel trying to crank it. I hate wasting fuel, so I gave up. I think using that old bladder was my problem, probably not enough pressure after being filled full so many times.

So I filled the Black Widow on my Jumpin' Bean and it cranked right up. It ran okay, nothing special, that's about it.

I'll make a new bladder and try the TD again tomorrow and I bet it'll run fine. That seriously cut into my flying time, I never got the chance to clean up the Stuntman, not to mention mounting the engine and making the new bladder. Now I have to do at least one more test run on the bench first.

I might just have to settle for flying the Bean if I get to go at all. Oh well, them's the breaks. This hobby has its disappointing days.

Sounds like you may have distorted the piston when you reset the ball socket? I've done that, and it doesn't take much, it will run ok but more then likely not as good as it should. Clean it up, slap it back together, run a rich, then slightly rich tank thru it, if it runs ok don't worry, if it doesn't replace piston/cylinder.

Mark Boesen wrote:Sounds like you may have distorted the piston when you reset the ball socket? I've done that, and it doesn't take much, it will run ok but more then likely not as good as it should. Clean it up, slap it back together, run a rich, then slightly rich tank thru it, if it runs ok don't worry, if it doesn't replace piston/cylinder.

The ball socket is still tight, I didn't need to reset it. All I did was clean and oil everything and run an alcohol soaked scotchbrite pad through the cylinder. I was not rough with it, except I added more pressure on a small stubborn stain near the top of the cylinder. I made sure I got the ball socket and the crankshaft good and wet with fuel before I cranked it.

Do you think that last week's old weak stretched bladder could have been the problem? It cranked and ran easy enough the first rich run and then for the next full speed run. It was after that it wouldn't crank and keep running more than a few seconds.

I'll probably order a new cylinder anyway, but the old one ran okay last week, except I had some trouble needling it for flight. Ran good on the ground, but I figured that was my inexperience. I was trying to set it rich like a bee before takeoff, and I've since learned not to do that; just set it WFO and send it off to fly. On my last flight I finally got it right and it ran pretty good.

RknRusty wrote: Do you think that last week's old weak stretched bladder could have been the problem? It cranked and ran easy enough the first rich run and then for the next full speed run. It was after that it wouldn't crank and keep running more than a few seconds.

My guess is that you cleared some junk out of the sprinkler assembly and caused it to run rich.

George

The sprinkler was clean. I had just cleaned the whole engine and that was the last thing I checked.
I made a new bladder tonight and it ran great. Now I can tell the difference with the hotter fuel, it ran faster and steadier than it ever has. I can tell that tubing gets weaker every time I fill it. So I'll just make a few spares to carry in the flight box. And I finally learned to leave the needle alone after it runs the first time and just finger pinch the line while cranking after that. Finding it the first time is the hardest part. It runs at about 3.5 turns with a fresh bladder.