Well it lasted nearly 3 months, but it was only a matter of time before something went wrong and I got a crash course in mopar mechanics

After intending to have a go at adjusting my carb (thanks to a sound lesson in the 750 holley courtesy of Keith - MoparKM) I found that the timing must have slipperd (Is this right?) as when turning it over a foot high flame appears from the carb

Thing is when I first brougth the car, the previous owner told me the car was over heating and that it may have been caused by the timing being off - so I paid a bloke ?50 to set it for me. So either I've been conned and he didnt do a thing with the timing (which I know isnt the case as the car ran well for a good 2 month after) or something is causing the timing to slip?

Any ideas what this could be and what I can do to fix it? Also Im not paying ?50 again to have the timing put right - can anyone tell me the settings for a 383 and any handy hints/help to get it right myself?
Any help would be great
Cheers,
Dave