Lost Compression on # 8 cylinder

[carnutjoef]

Hi, I'm new to the forum and I just picked up a 1967 LeMans with a 326 engine. One of the pistons let loose, the engine is shot. I found a 1969 Pontiac 350 in good condition. I disassembled the block and changed the rear main seal. Everything looked good, no ridge at the top of the cylinders, all bearings were within tolerance and rings are good, cleaned and reassembled. On completion I did a compression check, all cylinders were at 120# except the #8, zero. The problem is when I adjust the rockers to 20 foot pounds on #8 cylinder, the valves open even when the lifters are on the cams base. Rockers are all good, push rods are correct length and valves are both seated. I do get a compression reading when I loosen the valves to zero lash, but loose it when I reset to 20 foot pounds. I feel I'm missing something, I just can't put my finger on it. Any suggestions would be greatly appreciated. Sorry for the long winded thread.

 

[melsg5]

how do you know the heads haven't been milled? Beyond a certain point you have to start shimming the rocker arm studs to compensate for too much milling. Other thought is the lifters maybe clogged and not bleeding down.