So i had to replace my distributor today, when i went to re time the engine it was pretty much right on, at about 10 btdc i let it run and warm up and now it looks like its about 30-40 degress retarded. it runs fine and mechanicaly is timed correctly( the mark on the crank and rotor button match for #1 tdc) if i try to bring the timing mark back to where it should be it stalls? does anyone know what is going on here?

 

Harmonic balancers can go bad, to check it you need to see if the timming mark is lined up with the key way were the balancer slides onto the crank shaft, if there not lined up with each other then the balancer has twisted out of time and needs to be replaced.

 

ok after doing some research that's what i think may have happened, its the only thing that i can think of that would explain my problem