Adrian Jones wrote:
>
> Hi Folks,
> Here's an interesting little topic. ( Well I think so anyway)
> Is it possible to "fine tune" your carb mixtures by looking at the
> condition of your plugs?
Gazing plugs is only accurately telling you what the motor was doing
just before you shut it down. That is, if you wanna know what the plugs
are doing when cruising, then go out and cruise and, when nobody's
looking kill the motor, go to neutral, pull over and pull a plug.
Checking plugs in the garage only tells you how the car runs in the
driveway. (Okay, Larry, with an 'A' it may mean the same thing.)
> A recent post said that the outer plugs (#1 and 4) tend to run rich, at
> least on an MGB. Does this apply to a Midget and if so , why?
On my (now gone) Midget the front cylinder ran rich. I assumed this was
because it is first-in on the water pump -- gets the coolest coolant.
> If the engine was burning oil or if there was a slight ignition miss on one
> or more cylinders, wouldn't this confuse the issue.
Yes. Normal 'rich' running causes dry, sooty, black, coal-looking
deposits. Oil fouling is black, wet, gooey, yetch. This would be bad
rings. If the deposits are a white ash buildup on the electorde, it is
likely weak valve guides sucking in a little oil and what is left behind
is the additives in the oil.
> Is it OK to use a brass wire brush to clean the plugs.
Yes.
> JC Whitney has something that uses grit and is powered by the car battery.
> Cost $8. Anybody used it?
Spark plugs get worn out for two reasons. One is all the crap that gets
deposited on it that you might be able to clean off. The other is that
the elctrode gets worn with rounded ends. This is a bad thing as the
spark is easier to control (timing) when the spark can launch off the
sharp corners of new plugs. The Plug Sandblasters just wear out the
plugs faster due to problem number two.
> Are we looking for a light brown color? The cleanest plug so far,#4, has a
> definite reddish deposit.
If it is a shiny orangish-red glaze, almost shiny, then that is likely
pre-ignition on hard acceleration. Unusual. Caused by a lot of heat
happening real fast that caused whatever other deposits were on the
plugs to melt into the glaze.
It should look like a chocolate milkshake on the insulator. It shouldn't
have any speckles (pre-ignition).
> Don't we want a slightly rich mixture for more power? Wouldn't this
> eventually foul the plugs with carbon?
Not if only slightly rich.
> Should the spark plug gap be kept at 25 thou. I have a Sports Coil but
> regular CB points.
You could probably survive .032. Try it. The worse that can happen is a
top-end miss. You might try .035, too.
> In the mornings, I need to do the "in and out and in and out" thing on the
> choke as I go through the gears to keep it running smooth until it is
> warmed up nicely. Is this normal
At your age, you should be proud that you can do that and drive. It's
pretty normal if the urge subsides once the car is warmed up.
Bob Allen, Kansas City, '69CGT, '75TR6, '61Elva
|