2000 4.8 low compression

[Victorc]

I have a 2000 silverado 4.8. It has a misfire that you can feel and see on the misfire counter on a snap-on solus scanner. No codes. i did a tune  up 2 months ago. i tried moving the plug to another cylinder with the wire and coil misfire stayed at the original cylinder. i did a compression test all cylinders except #7 was 135psi. 7 was 60psi added oil it went up to 70psi. let it sit for a few hours and came back rechecked number 7 and it was up to 135psi. Rechecked this morning and still at 135psi. just wanting peoples opinion on what could be wrong or what i should check next? the truck has 272000 on it. if it went up more right away i would say rings for sure but it taking hours to come back up to compression.

[Brian715]

Sounds like it's time for some engine Restore goop...  

Just kidding. 

TBH if it were my truck anything that is causing a lack of compression on a 272000 mile gas engine isn't worth my time investigating any further.  Sounds like a tired 272000 mile engine that is ready for a rebuild. It's not like I would take the engine apart and only change the rings and then put it all back together.  If it's coming apart, it's going to the machine shop and getting bearings and seals and pistons and the heads are getting decked and the valves are getting new seals and lapped, etc, etc.  If the truck is still in good shape I would consider a 5.3 swap. All that is needed is the 5.3 and a tune.  It's the easiest swap known to man, and the 5.3 is probably easier to find than a 4.8l. 

[Victorc]

I have found a few 5.3. i know someone who can do the tune to 5.3. That is what i was think was just pull the 4.8 and swap a 5.3.

while i have it apart put a new clutch in it and a few other things that need to be done.