Quoting kenyon wills <imperialist60@xxxxxxxxx>:
See my text inserted in yours.
> I may have reversed the words as I stated what I did.
>
> The distributor wound up being moved counter-clock-wise from its
> original
> spot, twisting the vacuum advance module to the firewall and away from
> the
> front bumper.
OK, so you were retarding to prevent knocking or pinging, whatever you want to
call it! That's what we thought.
>
> The engine settles down and runs really, really smoothly at idle in one
> spot, but it pings like crazy when it's left there and gas is applied
> to
> make the car go. I have to keep it farther away from that sweet spot
> than
> the idling engine seems to want it. There is still some stumble and
> vibration at idle that I think should not be present.
It may be possible that your centrifugal advance is not properly operating.
Get a timing light, and with the vacuum advance disconnected, check the timing
between 1000 and 2000 rpm. In my 440's, its advancing about 10 degrees between
these speeds. I doubt that this is happening because it might tend to knock
less rather than more, but its easy to check if you have access to a timing
light. Oh yes, you may need a tach for this too. I am so used to having tachs
in my cars, I assume that everybody has them. It may also be possible that
your vacuum advance is over advancing, but I can't see how that can happen.
Again, you can check this w/ your timing light and see how much it advances by
connecting and disconnecting. I can't help you though with how much is too
much. You may need the FSM for that.
>
> If the pistons are coked up with deposits, would this cause pinging,
> dis-allowing the distributor to be placed where it most "wants" to be
> when
> I'm under the hood and playing with it without a timing light?
Possible. In fact, that may be the most likely case. Check and make sure
though that the centrifugal and vacuum advance are working properly.
>
> I have had the car on the freeway at speeds around 70-85 for 30-45
> minutes, and can't imagine going faster than that with the steering and
> prop shaft/motor mount? vibration issues that I must address.
Its not so much about speed as it is about load. These cars have such a large
engine that its hard to load it with steady speed unless you drive super fast.
You can load up your engine on 1st and 2nd gear w/out driving too fast. Just
lock your tranny on 1st from a standstill on a fairly open road and hit it,
wide open. Then, shift on 2nd at about 40 if you have 3.23 (or 45-50 if you
have 2.94) and hold 2nd till about 70-75 (85 if you have 2.94). Do that a few
times, and you should slowly start seeing an improvement. You may have to use
premioum fuel while doing this to avoid pinging. As the carbon is
progressively burnt off, you should be able to use the lower octane due to your
low compression ratio.
>
> Carbon comes from poor combustion? Is there a magic goo that I can add
> to
> the fuel? Techron comes to mind, but maybe that's just the intake side
> of
> things?
Carbon forms due to prolonged idling and very light load operation with little
heavy engine loading in between. Also, short trips with a lot of choked
startups with no heavy loading in between will cause them. The reasons are
two. At idle and light loads you have rich operation that causes incomplete
combustion as you said. Also, if you never push your car hard every now and
then, the peak cylinder temperatures from normal city driving are too low to
burn the deposits off, so they keep accumulating. At WOT, the peak temperature
is sufficiently high that will slowly burn off the deposits off, in spite of
rich operation. Given that Imperials have relatively large and powerul
engines, normal driving may not be sufficient to clean up these deposits, so I
think that this is typical of these cars.
I don't know if the additives help. These are usually good to remove deposits
from intake valves. Once the engine warms up, the additives will probably
evaporate and never contact the in-cylinder deposits. When I first got my
black 68 LeBaron a little over a year ago, the old man barely drove it (13K
miles in over 20 years) but occassionaly started it to keep the battery going.
Also, the choke was operating too rich, and the engine was pouring black smoke
when choked. The car had a lot of deposits. Even at 8-9 degrees BTDC spark
advance, it pinged a lot at low speed accelerations (non-WOT, just barely
moving off the light). After the 600 mile trip back, it still pinged. I
disconnected the choke and fixed the throttle linkage so I had the secondaries
to fully open (the old man never had the secondaries to fully open) and after
about a week or two of my driving, it was mostly clear, and you could hear some
pinging only at WOT if I tried to advance 10 degrees and over. Now, I have
about 12 degrees at idle and I never hear pinging. It did take a lot of hard
driving to get here though, but I can't complain, it was fun! So, the answer
is that it will be a slow process, but some hard driving can clean up most of
the deposits relatively quickly. Keeping the timing as advanced as possible
will accelerate the cleanup, as this tends to raise the peak combustion
temperature.
D^2
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