Valves/timing won't stay adjusted

[Chevk587]

Ok guys I did a new head gasket on my 87 k5 ran good then all of a sudden it was like the timing went out or valves out of adjustment no power rough running smells really rich . Re adjusted the valves while engine running got way better sounded/ran normal noticed it took a really long time for oil to come up to the valves thought it was weird . It sat for about a week came back started back to same problem. I'm thinking it could be an oil issue but even when I let it sit and run nothing is getting better still rough and rich not sure what's going on thought I would ask and see if anyone has had a similar issue.

 

[paratrooper307]

The adjusting while running works, but go ahead and redo it to get a baseline lash adjustment. Inspect your rocker nuts-I've seen older ones back off and not be able to hold torque. You will definitely want to check your head bolts and make sure everything is straight-you did follow the torque pattern in increasingly tighter steps, correct? Any kind of compression leakage due to improper installation is going to make your truck run poorly-and expanding metal with heat could intensify the problem. First rule of repairs is that if you have a problem you didn't have before, check what you changed. A compression test and leakdown test can isolate potential problems.

 

[dyeager535]

You talk about timing, did you remove the distributor? You are sure you got all the plug wires on correctly, plugs are good, etc? If you pulled the distributor, you made sure it's 0* with the EST bypass disconnected? The balancer is in great shape and there is no possibility the timing mark has moved due to failure of the rubber?

I'm reminded of this because my truck sat since October after installing the crate motor at 2AM...rookie mistake that I have no idea how I made, but the distributor was 180* out...obviously had rotated the crank and not put it back on TDC. Got that corrected and fired up no problem. But more to the timing note, I was worried because it was intermittently popping out the exhaust after I got it running, while I let it run for 20 minutes. I turned the distributor a tiny bit, and it went away. Went back to make sure it was set at 0*, and it was. With as much timing these run at idle, I wouldn't have expected that much difference in a couple of degrees base timing (in the range of 20-28* total timing at idle) on an EFI rig, but the difference was readily apparent.