Jon,
BINGO !! Thats what I am leading to with this topic. Mis-Fires
I think I may be getting some misfires due to the distributor shaft play. Heres why:
If I look at the wear and corrosion on the terminals inside the distributor cap, it
appears that all of the corrosion is on the "leading edge" of the terminals. That would
mean to me that the spark is jumping from rotor to the terminals _before_ the rotor has
lined up correctly.
So my next question is: Doesn't most distributor cap wear occur in the center of the
terminals? Meaning that the rotor has aligned with the terminal and then spark jumps
across?
I dont know what kind of terminal wear people get normally. Perhaps you can check your
terminal wear and let me know? I would really appreciate it.
BTW: Thanks for the time you took to getting your measurements. That was a really cool
thing to do.
-dan k
----Jon wrote------------------------------
That is certainly not the easiest place to measure! :-) Anyway, on
my '96 318, using a dial indicator I came up with about .120-.150 inches, so
about 3mm to not quite 4mm. (Sorry for the range - see "not easy to
measure", above.) ;-) I removed the rotor and used a large screwdriver
in the keyway of the distributor shaft to determine that most of the play
on my truck was coming from the fit of the rotor on the shaft, as opposed
to the shaft itself. (The shaft did move ever so slightly, but it was
fairly negligible, it probably accounted for something like 25% of the
total slop.)
Anyhoo, it sounds to me like we're getting basically the same amount
of rotor play, so it doesn't seem like its anything to worry about. (I
suspect the engine would probably be OK even with larger amounts of play
since the shaft is always turning in the same direction, it would
basically "load up" to one end of the play direction and pretty much stay
there. If the play was really significant (in the shaft itself), it would
mess with your fuel sync a bit; if the play was significant in the rotor to
shaft fit, you might get some misfires due to the timing misalignment.
That would have to be a fair amount of slop though; something on the
order of 20-30 degrees - I didn't think to measure the shaft to rotor tip
distance, but assuming its about 1.5", that would mean the slop would have
to be something on the order of 1/2" to 3/4" at the rotor tip before you'd
get misfire issues due to rotor slop.
Dan K.
'92 Grey Dak CC, 318, 4x2, 46RH, 3.55 rear, 235/75R15, PS, PW, PB, PL, AC.
Mods: Cool air, K&N oil/air, 180* T-Stat, Autolite 3924s, re-located IAT, Trans-Go shift kit.
Future: Swap motor for a slightly modified Magnum 5.9L engine.
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