How are you measuring the weak spark? From a sparkplug wire?
Try pulling off the HT wire from coil to middle of distributor and check the spark from that wire to frame while cranking. If that is a strong spark, that will tell you that either the rotor, distributor cap, or plug wires are the problem.
Do you have a ballast resistor? How are the connections on that? Those can easily be loose and cause weak spark. Try just bypassing that resistor (briefly for a test only) to see if that is the problem.
Then to see if the ignition switch is the problem, replace the positive feed to the coil with a direct battery connection (again, briefly for a test only).
Thanks for your help. I done all the sugested checks, no good, last one was hookup a seperate battrie and it ran well. Rehooked up orignal battrie and i noticed the amp gauge was showing a discharge with the engine running, Disconed the voltage regulaitor and fixed the problem.
The fix, fitted a new voltage regulaitor. I havent struck this before.
Thanks again for the help.