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Hello, my name is Joe
If you have confirmed a strong spark on all spark plug wires with an HEI spark tester, and have good fuel flow into the carburetor fuel float bowl, then I suspect the no-start is caused by wet spark plugs.
The carburetor and choke may be malfunctioning, and is causing the spark plugs to become wet with an incombustible mixture.
Try removing and cleaning or replacing all spark plugs. Also make sure the choke is not stuck closed.
If the engine starts with the clean or new spark plugs, then I would suggest rebuilding the carburetor, or repairing the carb and choke system as needed.
It is not likely there is a mechanical issue , unless the engine has very high mileage.
Just checking in to see if you need any clarification on something which I stated above. Please remember to rate my service, so I can receive credit for my help.