I assume from your handle that it's a 62, right? Check to see if the coil you installed has an internal resistor in addition to the one you replaced. If so, the primary ignition circuit current will be too low to develop a good spark. The voltage at the + terminal of the coil should be approximately 9.5 volts with the engine running and the charging system voltage at about 14.5 or so. An original-equipment type coil SHOULD NOT have a resistor internally in the primary circuit.
Jerry

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