[mustangman65_79]

I wounldn't use a four bbl with vacuum secondaries because the other two bbls will not kick in till higher RPM. They work on vacuum, so that when there is less vacuum, say when u have it wide open at higher RPM, they will open all the way. Mecanical secondaries work when u want them too. The farther u push the pedal, the more they open up. U can smash the pedal at idile, and all will open up right then, not later.

I'm going to put in a new 670CFM Holley in my 289. that might be too much gas for a stock engine. I'm also putting in elec pionts with a 45,000 volt coil and 9mm wires. That should handle all that gas just fine.