I have the RCV 58 and I've found that you need a fuel containing a minimum of 10% nitro and an OS F 4 stroke plug. I use an all synthetic fuel called Prosynth here in the UK. This is absolutely the best fuel available for any glow engine, and especially RCV's
See http://www.westonuk.co.uk/index_045.htm

However I'm not sure that you can get it in the States. You will find that if you use a fuel containing all castor your new RCV will last about a season and will look like a toffee apple, as a couple of my friends found out !

Just make sure that you treat it carefully during the first hours running and you will be rewarded by a great running engine.

Hope this helps