Q: just replaced the timing chain and guides on 86 nissan z24 and now it smokes bad and now power

If these symptoms did not exist prior to replacing the timing chain, a possibility is the valve timing is off because the new chain is mispositioned. You can get an indirect indication of incorrect valve timing by measuring engine vacuum. If engine vacuum turns out to be low (out of spec) at idle, given the work you did, that would point toward the valve timing being off. Regardless of what the underlying fault(s) turns out to be, if you desire a diagnostic, and the required repairs, the recommended service to request is an engine loss of power diagnostic. If you request the engine loss of power diagnostic, the certified mechanic will get this resolved right at your location. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.