Engines

[Jonathan]

On the home straight with my latest build diamond demon,  first time electric.  Sorting out my old engines for my next build,  The Answer by cumbrian models. Last used the 25 years ago,  I put them away cleaned and oiled,  just ordered some fuel,  quite a bit more expensive than last time haha.  Looking forward to starting them up. Will probably use the original Mills .75 , it was a sweet little engine I remember. 

[Rich Griff]

May I ask please, what oil did you use and are they still free turning, other than compression of course ?

[Jonathan]

Yep I used Model Technics After Run Oil, they all turn over nicely,  still going to give them a clean before starting 

[Tim Hooper]

I'm no expert, granted.

 

I give my diesels a squirt of automatic transmission fluid (ATF) if they're not going to be used for a while.

 

Tim

[Nigel R]

I used to use ATF but it can contain a fair amount of sulfur which isn't a great thing.

 

Air tool oil is a better option and is pretty cheap. 

[GaryW]

I use this air tool oil in all my engines Glow & Diesel

 

https://www.screwfix.com/p/pcl-iso22-air-tool-oil-1ltr/568hy

 

 

[Jonathan]

The 2 Mills engine's in my photo show my original one my dad bought me in the late 60s the other one I purchased in 1992 a India replica,  after a couple of fights and a bit of a crash landing the prop shaft got bent,  the shaft was slightly smaller in diameter than the original and possible not as good quality metal,  monkey metal springs to mind haha,  fortunately my dad turned me a new shaft for it , overhauling the complete engine even though it was new. I will be using the original engine in my next build. 

[Jonathan]

Just purchased a new Master Airscrew 7x4 prop, to replace my old original,  which I used on my first Diamond Demon 48" wingspan 25 years ago, it powdered it fine. I will be using the new one on The Answer  a 44" wingspan,  when ordering the prop I was questioned about it being too small,  suggesting a 8x4.  I've gone with the 7x4. Any thoughts 

[Engine Doctor]

Mills 75 are very happy on a 7x4 although a wooden or nylon would be my preference to avoid a bent or snapped crank. The Answer is a loverly flier. I built mine qiite a few years ago and fitted an OS 10 with 35 meg radio and standard srvos as mini servos were very exlensive .That setup IMO was too heavy and  the os over powered the model  With modern lightweight radio and mini servos a a  Mills 75 should be fine. 

[Jonathan]

Thank you Engine Doctor, appreciate your knowledge