Are these Compression and Leakdown Test Results OK on a 1965 356 with a 1990s rebuilt engine with under 6,000 miles?

CYL Compression in LBS Leakdown

1 135 4%
2 140 12%
3 135 8%
4 135 6%

 

compression looks ok.. leak down looks a little concerning on #2.. in all honesty they should hold at least 90%.. ideal is about 95%-100% (ie.. holding that much per cyl.. you say youre engine is letting 12% by on #2, which means its only holding 88%.. which is concerning)

make sure your valves are adjusted properly, drive it for an hour, then recheck the numbers as there could be some carbon on the valves thats not burnt off that could be holding it open a bit.

edit.. engine has less than 6000 miles on it!? those numbers are very concerning then. who rebuilt it?

compression should be higher for a motor thats that fresh.. but then again who knows what compression it was built at and how many shims were used onm the cyls and what the story with the heads are.. but the numbesr are within the same range of each other on compression so that should be fine.

leak down concerns me with a motor that fresh... again.. readjust the valves and recheck everything.