Roger Nelson wrote to All:   
      
    RN> Calling all timing experts!   
      
    RN> A neighbor of mine has a 2002 (I think) Chevy with a V-6 engine and   
    RN> he was telling me a few days ago that they did some internal work on   
    RN> the engine and when they put it back in time, the #6 cylinder had to   
    RN> be at TDC or else it wouldn't start.   
      
   That isn't quite true. If he has installed a new timing chain, it's easier   
   to set the cam:crankshaft timing if both timing marks are close together,   
   rather than far apart as they would be if they set it on #1 TDC. That   
   would put #3 at 180 out from #1, not #6...   
      
    RN> In my old days of fooling with engines, prior to the V-6, that would   
    RN> not have worked,   
      
   It works if you know what you're doing. I've set up my race motor in the   
   same manner. #6 at TDC puts the cam sprocket timing mark at the bottom of   
   the cam rotation, aka 180 out of sync with #1 ... and the crank timing   
   mark at the top of the rotation (#6 at TDC), making it an educated eyeball   
   alignment, rather than a 12" straight edge alignment.   
      
    RN> so I think they had the distributor 180 degrees out (or off,   
    RN> depending on how others phrase this).  Finally, I thought the   
    RN> conputer would take over this setting?   
      
   Initial timing of an engine is to set #1 at TDC and then install the   
   distributor so that the rotor is pointing at the #1 cap terminal (and on   
   the V-engines, at the #1 cylinder's physical position).   
      
   He could be right in that he installed the distributor when #6 was at TDC   
   IF the rotor was pointing at #6 cap position...   
      
   He may correctly set it to 180 out if he has #3 at TDC (cyl in a   
   compression mode where both intake and exhaust valves are fully seated).   
      
   But then, there is the bastardized crank that the 2.8l - 3.1l V6 engines   
   use with offset crank throws in an attemp to make it a smoother running   
   engine...I'd have to know more about which engine and what year to make   
   any other descriptions of it clearer.   
      
    RN> Anyone who wants to contradict my opinion(s), feel free.  (-:   
      
   The CPU will take care of the 'spark advance and retard' needed to make   
   the engine run as efficient as possible, as todays cars use a lot of   
   electronic sensors for feedback to maintain that.   
      
   He would still have to make the initial timing setting (#1 usually zero   
   degrees TDC) to make that work as designed.   
      
   PS - my 1988 V8 Camaro required that the mechanic disconnect an under hood   
   wire that allowed the CPU to advance/retard the timeing, upon initial   
   timing setting, then reconnect it when set.   
      
                   R\%/itt   
      
      
   ... Mark Owen: "Hey, did you ever hear anything about that beer?   
   ... Fellow SEAL: "You believed that s**t, I bet you voted for change too,   
   ... SUCKER."   
      
      
   --- GoldED+/W32   
    * Origin: Texas Lone-Star - Texan, American, USAian  (1:387/22)