Timing is out but deviation is steady: set timing or major overhaul

[steved0x]

Make sure the engine is nice and hot or else you mat get false readings that show higher deviation than actual. That said, -10 and -7 are quite a lot, and I am surprised you don't have a check engine light from the -10 reading, as I think the threshold is either -8 or -9. The spec is +-6 degrees. I personally am at -5.xx (very close to -6) and holding steady so I am just watching and waiting, if it ever makes a significant jump or over time gets much higher I plan to have the chain guides (or whichever the name of it is, the pieces that wear that cause the deviations)

I don't know if timing being off can cause readings like this - it seems like timing off would cause bad running.

Steve