.010 and .020 top ends

The .049 crankcase is a good bit larger than the .010 and .020, so the cylinders will not fit.

cribbs74 wrote:Nope, not even close. There are ways to detune your .049 though.

Ok that sounds promising very strange for me to want to detune an engine first time ever in fact but that is what is needed for this project ... go on do tell how can I detune I have a muffler head shims timing shims etc and some old non spi top ends am I anywhere near yet ??

Simplest one Phill, is to turn the prop around.
Then lower nitro, which will give a longer run time too.
Run the needle rich so runs off peak.
All without even needing a wrench.

Yep, the backwards prop works to tame it. So does a 6" prop. An old non-SPI cylinder is a good way to go, especially if it only has one bypass port. I hate to resort to running rich, but it'll do in a pinch. You might get a varnish buildup that way. Add another head shim or two to lower the compression. But that might make it harder to crank.

Ok thanks John thanks rusty
Will turn the prop around run an old non spi barell put a shim in put my silencer and run a bigger prop would I be in 020 territory do u think (running of song rich) that is or am I still overpowered
What does an 020 swing a 6x4 at (ball park figure ) also an 010 for reference would be useful although I realise a 010 probably wouldn't ever use a 6x4 just wanted to get some idea of power I'm tying to get too any idea what you would all consider ideal for the model I'm building at the mo on my other thread "free flight project"
Cheers for the help and tips never thought of turning the prop around !!!! That's why I love this forum ... Many minds and much experience

Just to add not really too worried about varnish buildup as the timer I will be running this with only has 22 seconds duration and all my engines get a full strip down every couple of months but good to know will keep on top of that rusty cheers

You would probably overheat an .020 with a 6x4 prop, that's just outside of its design limits.

I don't understand the problem, 30" wingspan and a cox .049 is a good combination. Just let the engine pull the plane up high, the timer stops the engine, and then free-flight down.