Code P340 Timing '99 4.3 Vortec

[azmikeaz]

have code 340 timing sensor error on a 99 2wd S-10 4.3L "X" engine with balance shaft and side terminal distributor. Replaced sensor in dist. and also replaced timing chain set. still have code 340. When I removed the distributor I'm sure that the rotor went back in same position ,but not certain that the distributor housing is exactly as it was before removal. I haven't been able to find any info on setting the timing prior to start-up. I attached a timing light and the mark on the harmonic balancer appears to be about 15 degrees advanced from the stationary mark on timing cover, at idle. How do I set the distributor timing pre-start? and is the timing adjustable if so what is the procedure.