It's been nearly 20 years ago that I got my first, VA MK 1. It was the first, new, 1/2A offering that was affordable at 50 dollars and it used modern, AAN technology. For 35 bucks today, with inflation, it's a bloody steal.
Good advice so far but let me add that you MUST use an all castor based fuel of at least 20% oil. Or at least one that is half and half, castor/synthetic. Be wary of fuels that say castor/synthetic blends, some have only a token amount of castor. Like Cox engines, the piston pin is completely shrouded, the pin sees very little fresh lubrication. Only castor will give you decent life in the wrist pin area. When Dan Rutherford was selling them, he had to take out the piston pin carrier and file notches here and there to allow the pin to get some lube.
A G-Mark throttle was first tried on mine, back then, and was OK but not perfect. The addition of an adjustable airbleed made for virtually perfect throttling.
The Cox RC .05 throttle is the better choice as it has the quite necessary, adjustable airbleed.
The very, very, early versions were nickle plated all over, inside and out. I have two of them I got from,,,, well, I wish I could remember.
As an RC engine, mine do their best work on a 5.5 X 2 APC prop on 25% nitro delivering 22K. More nitro is better but make sure your oil is at least 20% and all castor or half and half, as mentioned.
I still have 5 of them and with today's micro radio gear,,, the possibilities are endless.
The best prices and excellent quaility, micro radio gear can be had at HobbyKing. My old Cannon stuff looks positively HUGE in comparison.
I've been tied up with serious health and family issues for the last 5 or six years but got out to the park last summer. Most times I'm ignored but now and again, youngsters and even adults who have flown WalMart lekkies would come up and be amazed that such tiny engines were even possible. The kids especially get a real kick out of the noise, smoke and fury that the litle guys put out.