P1345 is for minor variations. What you have is a major variation.

 

The computer can read a minor variation, but no a major one? I can dig it. The cam gear inside the block where the distributor drive gear mesh is fine. The distributor drive gear looks fine. I marked the rotor to the distributor body. After attempting to determine if timing had jumped according to https://blazerforum.com/forum/engine-transmission-35/edi-engine-timing-10626/ both trys the rotor pointed just before the "6" pointer incased in the distributor body. It was close but not perfect. I also checked for play in the timing chain by rotating the crank clockwise until i noticed the rotor moving, then stopped, marked the engine and crank, than rotated the engine counter clockwise untill the distributor rotor began to turn. Measured about a half an inch away from the mark i placed. So that means there is some play, roughly 9, 10 degrees worth i'd say off hand. Is that below specs?

 

I have never done what you described. There should only be a minor amount of backlash between the gears on the cam and distributor and that can be determined by just moving the rotor itself. The rest would have to be in the timing chain and 9-10 degrees does sound like a lot, but then again, the motor only rotates in one direction...

 

True. I know you arnt a fan of the Haynes manual, so I have to ask. Do you know of any detailed write up's, maybe with pictures, for the removal and installation of a timing chain on the 4.3L vortec? I noticed the tansmission cooler lines run right below the oil pan bolts. Just my luck

 

I tor apart the timing cover and the chain, sproket and gears look perfect.. slight play in the chain. Pulled the sproket off and the dots match perfect. Tthe timing chain definatly didnt skip. This is aggrvating

 

not trying to dig up an old thread but what did you find to be the issue in the end?