Initial timing question

[PhilB]

I have a timing question on my 351W with stock Duraspark II distributor. The engine will barely run at 14 deg of initial timing. At around 25 deg initial (set at 1000 rpm with vacuum advance disconnected), it runs fine with no pinging or hard starting. The distributor was curved for 10 deg mechanical advance (20 deg at the crank) at about 2500 rpm. Crank/timing mark correlation was verified with a dial indicator and is dead-on. Using manifold vacuum, it does bog under WOT at 30-40 mph but under steady and heavy acceleration from stop it’s fine. I think using ported vacuum and further carb tweeking might solve the bog problem. What I can’t explain is why initial advance has to be so great. I haven’t pulled the timing chain cover to verify cam timing but I have no reason to believe it’s off. Cam is 270 advertised, 224/224 at .050” (Comp Cams Magnum). I’ve used two different timing lights with the same result so I don’t believe I’m getting a double reading. Any ideas?