There was an article in Fly RC about timing an engine. Basically, it involves the percentage of nitro in the fuel, the heat range of the glo plug, prop and the cylinder head temp. This will require some experimenting to find the right combination for optimum performance/power from your engine.

The least expensive (and least frustrating) way is to get yourself a decent ball bearing engine. Thunder Tiger PRO, Evolution, OS and possibly the GMS engines will provide substantial power/performance gains with prices from around $65 - $115 for a 46 size engine.

The LA series (and other bushed bearing engines) are normally economy engines and do not lend themselves easily (or cheaply) to performance modifications.