Help! 01 Challenger 720 weak spark?

[Austin69]

I rebuilt both engines in my twin 717 01 challenger and installed the left engine and it has new carbs too that worked perfectly before but it wouldnt start or have any sort of combustion and i installed the rotary valve and magneto/armature plate correctly and did a spark test and it seemed really weak i had to turn the lights off but now im seeing on forums its normal. These motors ran before why wont the left engine start? I havent installed the right yet btw.