I would do a search on antifreeze. There is a method of using Prestone to clean the engine.

I would also look at Carb Cleaner. Gunk sells a kit that you can use to dip your Holley carb in, and it works great with an RC engine. It is basically a 1 gallon paint can filled 2/3 with cleaner, and a basket. Give it a try, it worked well for me.