Hey all! Got a quick question about engine timing....

1991 GMC Jimmy 4x4 4.3L "Z" engine TBI

Here's the back story. I recently put new intake gaskets (were leaking coolant) and new valve stem seals (was blowing blue smoke) and a new water pump, new lower rad hose, new serpentine belt, and rebuilt the throttle body (new gaskets, o rings, fuel regulator, etc)

I got her all back together and running! Ya me! Never done anything remotely like this before. I watched alot of youtube vids and read forums and the chilton book back to back a few times. I had some knowledgeable help too. Anyway....

I set the timing to 0 degrees...and the engine was running but didn't seem quite right. Came back inside, did some research and learned about the unplugging the EST wire thing. Unplugged it and checked timing. Was at least 12-15 ATDC and running fairly rough (sounded nice tho, throaty...haha). Brought it up to zero degrees again and it was running better. Shut it off and plugged the EST wire back in. The timing is now up to around 10-12 BTDC. Seems to be running well. Drove it around all day. No stalling or miss fires or knocks....but it still doesn't seem quite right. Maybe a little sluggish, not as smooth as I think it could be. Does that number seem right? Or should it remain at 0 degrees after that wire is plugged in.

On a side note, when replacing the valves, we removed lash, and only did a half turn on the nut. I've seen everywhere from a quarter turn to One full turn in the chilton book, to 1 3/4 turns. Could this be an issue? You can hear maybe a wee bit of chatter through the wheel well, but not much. Most of the "chatter" sound seems to come from the TBI fuel injectors.

Thoughts??? Thanks in advance.

 

yeah you did it right, time it to 0 with it unplugged and the computer advances it. could be any number of issues, distributor advance might be bad or other issues

 

91 4.3 timing specs?? - ChevyTalk --The Social Network for Chevy Fans