Spent yesterday and today trying to get my 300 to start, last week was running okay and would start after 3-4 cranks. But yesterday would crank but not fire, I had thought I had found a good timing sweet spot but to suddenly not fir has me baffled. So I checked fuel-ok and ran straight from a can to be sure, but I have run new lines recently all the way thru from tank to pump so I doubt it lines. Checked spark-ok from coil thu to plug, it's a pertronix plug and play with ignightor 11 Cut a long story short, finally today adjusted the distributor as I was cranking, got it running then dialed timing back to around 15 before and had idling fine and then 15 minutes later back to not starting again. Can see carb squirters working, double checked I had spark but back to playing up. Any ideas?