No spark and i can only get 5V at the coil.

This all gets down to the basics, when it won't start

COMPRESSION. You need so much compression. This is open to discussion. Some say more than 75 psi, some say an old worn engine will run with as little as 50. But you MUST have some. A slipped timing chain or other cam / valve troubles is the biggest pitfall here, and can also affect SPARK

SPARK....You need a good hot spark and AT THE RIGHT TIME. Slipped timing chains are pretty rare, but on some engines (older Ferds) slipped timing marks on the balancer are not. Once you actually HAVE spark you can check timing on the starter

FUEL.....Good fuel. Make sure not too much. Pull the plugs and inspect. Are they wet, fouled? Dry? don't be afraid to prime a bit of gas right down the carb throats. Use new, "good" fuel.

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With experience, you can forgo some things. EG if the thing "cranks normally" you can get a good idea that it has compression. If it "spins over" or thumps and makes other weird "effects," then it's time to get out the compression gauge / leakdown tester

Checking spark. This should have been fixed "the first day." ISOLATE the problem. SIMPLIFY the problem. Don't worry about side issues until you get the spark FIXED. Check spark right at the coil tower with a grounding probe, which bypasses such things as bad coil wire, bad distributor parts, bad plug wires, or fouled plugs.

Fuel. To repeat, pull the plugs, are they dry or wet. Oil fouled? Hell maybe the needle /seat is stuck open and dumping all sorts of fuel "in there." You have to think

Compression, spark, fuel. Those are the three