Moly rings lost their seat?

[Ratt643]

I rebuilt a 350 about a year ago. The cylinders showed no wear and no ridge up top. I used a flexible hone (320 grit) to break the glaze, using the same amount of strokes on every cylinder. The cylinders are .030 oversized. I used moly rings from Speed-Pro and assembled the engine. The heads were old 882 casting heads that I just bolted back on. I installed a new summit 1104 camshaft and did the break in with 1 quart of Rislone oil additive and 30 weight non detergent oil. No metal in the filter and no metal in the oil after the break in. I drove 600 miles to Detroit with the engine for the Woodward dream cruise. the engine ran great and didn't use any oil. I changed the oil again before I headed home, again no problems. After about 10 months of off and on driving, it broke a rocker stud. I pulled a compression check before pulling the valve covers to find the offending cylinder. all the cylinders registered 80-90 psi with the carb wide open and no plugs in the engine. The plugs had some oil on them but not enough to foul them. I was told by a fellow rodder that some moly rings have a tendancy to "retract" and loose there seal. I put a small amount of oil in each cylinder and pulled another compression check. Only an increase of 5 psi to 90-95 psi. I know the rings are in the proper orientation and not installed upside down. I think the heads may be to blame but highly unlikely to be on all cylinders unless the guides and valves are just worn out. I have a new set of World Products heads to put on the engine, but don't want to go thru a lot of trouble installing the heads with no increase in compression. There is maybe 2000 miles on this engine. it never runs hot, even in traffic. Runs 180-195 degrees. Anyone else run into this scenario?

[maxwedge]

Assuming the engine spun over fast enough to get an accurate reading, before you pull it apart, do a leak down test on at least one cyl. on each bank this is the only way to determine where the cylinder pressure is going, if the leak down is more that say 10% and you hear it in the crankcase than the rings at least are done, then take it apart and see what is what, BTW 320 hone is some what coarse for moly ring, and of course the cross hatch pattern is equally important.

[hoppedup]

it sounds like u didnt get them hot enough to seat to start with
u almost have to cook a block for u get a good seat on molly rings

[maxwedge]

Originally Posted by hoppedup

it sounds like u didnt get them hot enough to seat to start with
u almost have to cook a block for u get a good seat on molly rings

No such thing!!! Research how to seat Moly rings.

[denisond3]

During the compression test did you let the engine turn at least through four 'compression' strokes? I always do that - cant get decent readings otherwise, though I havent done a 350 ever, work mostly on small 4 cylinder engines.