timing - keeps changing

89 S10 Blazer 4.3 TBI
Replaced Engine
Most every sensor you can think of has been replaced

everytime you set engine timing, turn off and back on timing changes. have followed all procedures on setting timing every time you turn it off and then on its timing changes.

Any ideas
:banghead:

check crank pulley to see if seperating from hub

When you time it are you disconnecting the ECM from the distributor? If not you need to... Also remember you have knock sensors that help control timing.

ok i seem to have gotten the timing to work properly again, it is just running rough now and kind of low idle. any ideas

I have that same problem with my K5. Could be TPS. Any check engine lights?

your timing chain is worn out, got slack in it.
ive had this happen in the camaro.