Stroker,
I don't understand how total can only be 24* at the crank? 16+18 = 34. If vacuum is added, it will be even more. What is an fob plate? Do you use a dial-back timing light to see advanced timing? What am I missing? Is the timing not additive?
A page from a Sun manual specifies: 10* @ 500rpm (vac disconnected); 11-15* Centrifical only @ 2500 rpm; and 28-38* total @ 2500 rpm, at the crank, for a 273 w/ 4 barrel.
Does your carb have adjustments available, other than the jets?
Don't you read your plugs, or do you go by how it runs and performs?
Thanks, Richard