Car wont start

So far ive added new coil plugs dis cap and ht leads, rebuilt the carb. And added a fuel filter and a no return fuel valve, plenty fuel getting through coz it can be seen in fuel filter. First thing in the morni g i can try starting it 20 times n wont run, roll it down street and it starts first time. After the 1st bump it runs perfect and will start on the key, im thinking maybe the starters abit weak? Would that make sense? Coil reads 10. Something volts when cranking. Ordered a starter motor but id be interested in anything else i could try

Is the engine turning over fine on the starter motor?

Yes it turns over alright just didnt know if it might be abit weak coz its original

If it's only turning slowly, I would first suspect the battery or perhaps poor wiring, electrical contacts or earthing