Over last Summer I rebuilt my 312ci Y.
Why is my car so painfully slow? I have no power on tap.
Ive read that Y blocks are pretty darn tasty and quick off the mark.
My Mercury has a 2 barrell intake with Holley 2 barrel carb. Is this the reason?
If I stamp my foot on the gas, I get a major flat spot as it seems the carb starves the engine of the fuel required for any decent acceleration.
The carb has been fully rebuilt. Would a 4 barrel carb & 4 barrel intake solve this?
Picture taken in 1960. Funnily enough it still looks like this! 
1959 Mercury Monterey 312 Y Block. NORFOLK, ENGLAND, UK.