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


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... Fellow SEAL: "You believed that s**t, I bet you voted for change too,
... SUCKER."


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 * Origin: Texas Lone-Star - Texan, American, USAian  (1:387/22)