OS 10 La Diesel

What prop size and fuel are you using?

There is never a certain compression setting that is absolutely perfect for both idle and top revs. Usually the lower revs will require a little higher compression ratio than what is optimum at maximum throttle. So they will tend to miss a little on the lower revs, in order to not be too high on the compression for full throttle (which would be damaging for the engine). From your description it sounds as if the low end might be too rich, try leaning it out and it will miss a little on the low revs but have a nice acceleration when you advance the throttle.

Just like glow engine you set the high end first, lean out and then increase the compression if it misses. Then set the low end for a good acceleration using the low speed needle, rather than the lowest idle possible. While glow engines accelerate well when a little rich, diesel engines accelerate better when on the lean side so that it doesn't just choke on the extra fuel that it gets.

Here's one of my engines when set a little too much on the lean side (and too low compression), gives a very good acceleration though;

I use my own mix of fuel. I leaned the engine out to the point it started to die and then richened it up. This did not help. I just have to run it a little richer to keep it smooth. It still idles good like this. The pickup is not instant. This engine does not have an airbleed. The FP version did but the did not pass this onto the La.

What mix and ignition improver do you use?

I don't have any of the LA engines myself, but on the the FSR and FP you can always swap in one of their .15 carbs, as these have a low end adjustment. When you lean the mixture you also need to check the compression setting as these are linked. A leaner setting needs a higher compression setting.

You can also try with different props, what are you using now? A higher load needs a lower compression setting.

For the acceleration you need to listen and distinguish between a hesitation due to too much fuel (engines misses/stumbles, sometimes knocks and there is plenty off smoke) or a hesitation due to lack of fuel (less smoke and a weak fireing).

I do not think a 15 FP carb will fit a 10 La. A 10 FP carb should fit though. I do have a 15 FP that I would love do turn into a diesel. Do you know where I could get a conversion head for it?

Yes the .15 carb might not fit. My memory fails me but I think the FSR had an airbleed and the FP, I have swapped around and can't remember which is which...

Try with Davis Diesel Development, they make heads for the LA series. There are also lots of nice dedicated diesels, like PAW and PARRA, then you get a nice working disel straight away (and an extra head is not cheap). If you are new to diesel engines it is also a good thing to begin with commercial fuel so that you know what it should run like before you blend your own.

He is a PAW 09 engine with the stock carb (no low end adjustment); PAW 09

I have OS 10Rc and Os10 La, the conversion of the diesel I've never heard of. where there
to buy a cylinder head? Looks interesting!

Here you go:

http://www.davisdieseldevelopment.com/price_list.html

Figured since this came up I would state what was causing topend issues. There was a large number of bubbles coming from the needle. A quick prop balance should fix it.

Rolla