My son-in-law had a lifter stick on his motor. worn lobe, 3 bent valves. He had the heads re-done and put a new cam and lifters in the block and now has a new problem. Passenger side bank has all holes showing 75-80 on compression. Driver side is all 120-125. Needless to say, the car runs horrible. What is wrong with this?

Were the pistons checked for damage on the side where the valves were bent? Did you reuse the head gasket or use a new one?

Adjustable or non adjustable rockers?

There was NO tear down of the motor. We have NON adjustable push rods and there was NO damage to the top of the pistons. I just don't understand why one entire bank of pistons is carrying 75 lbs and the other complete side is carrying 125 lbs compression.

Have you done a wet test on all cylinders, or just dry. This will tell you if there is a problem with the rings or a problem in the heads.

How does the engine run? Does it miss and stumble?
Try warming it up, then do a compression test.
Usually we take out all the spark plugs first, then disconnect the fuel line, open the carb all the way and test.
Watching the comp.gauge needle, take a reading after the needle jumps twice...say as in it jumps up to 75 lbs, and then You turn the motor a little, more and then jumps to 100 lbs...NOT by cranking for 5 minutes and then taking a reading!
You can also squirt a little oil into each plug hole, to perhaps see, if the rings can be worn out..usually You will get a higher reading doing this.
Did You flush out the motor, or change the oil and filter at least?
Now is when You should cut apart the oil filter and see, if You can find any metal particles in the filter.
Thats a real eye opener!

do you check to see if any rags were left inside the heads or manifold during re-assembly? just a thought. dave #1355 ss/ea

were the heads shaved in the rebuild?

Thanks for the help. We discovered the problem. When the cam was installed, the cam gear bolt was not tightened properly. The cam alignment pin then wore a notch in the gear throwing the cam timing off probably 10 degrees allowing the valves to be ever so slightly open. New gear and all cylinders are now showing 165

Better keep an eye on your oil pressure! As previously stated,the metal particules from those worn lobes are playing around in your engine and sooner or later will end up into your bearings and destroy them.Oil pressure will be lost and you will be facing a rebuild.I am only speaking from experience after being told by a legendary engine builder(That we have all have heard of) not to worry about that lobe material floating around! Good Luck! Keep us posted!