i have a 87 firebird, with a 305 carb, it has a edleborck 4 barrel carb, hedmen header, flowmaster exhaust, no cat, edlebrock manifold, it has a cam but im not sure what brand, and a hurst short throw 5 speed. this car was a 6 cyl. the guy i bought it off of put the 8 cyl. in im not sure from what thought, but i know he rebuilt the whole thing. just wanna know how it would run on the 1/4 mile

 

You got to run it your self

 

There are way too many blanks that you can't fill in for anyone to even begin to guess what it is capable of running. You're just going to have to buck up and take it to the track.

 

A few casting numbers along with a quick run down the track will answer most of your questions. As Stu mentioned there are too many variables to accurately predict an ET.