I just took a '69 Firebird out of storage and had a compression and leak down test done to see where the engine stands. The motor is a 350 with 400 heads and a 4bbl Rochester. Compression ranged from 140 to 157 and the leak down put up ranges from 40-57%. Curious what these numbers mean and if the engine is in decent shape or needs to be rebuilt right away. Thanks for any help.

The leakdown numbers are pretty high but you mught want to put some miles on it and retesting before proceeding. If it has been sitting for a while, driving it will tend to improve the readings. Also, make sure the engine comes up to temp before starting the test. Do you know what brand of leak down tester was used? There is quite a variance in readings.

Generally I consider 10 to 12% leak to be normal for a used engine in good condition, with anything past 20% a sign of needing a rebuild. On race engines, I cut those numbers in half.