>It sounds to me that, instead of a problem with the primary circuit, there
>is an unusual load from somewhere on the secondary of the coil.
Refresh the memory of someone who's spent too long reading British-written
manuals: the primary is the low-tension circuit comprising the white wire
from the ignition switch, the white-black wire to the distributor, and the
various components inside the distributor, while the secondary circuit is
the high-tension lead from the center terminal of the coil to the carbon
brush in the distributor cap and thence to the spark plugs, yes?
>I'm not sure of the significance of all that, but I would believe that if
>the primary lead from the coil were intermittently shorting to ground, or
>if the capacitor were shorted, you simply wouldn't get any spark. The car
>wouldn't run poorly - it wouldn't want to run at all!
Which is what it's doing, but intermittently.
>Maybe, and maybe. By the time you read this, you may already know the
>answer. Concentrate on the secondary wiring, including the wires, the
>distributor cap, and the rotor. I would bet that your hot coil and poor
>running are caused by some of the coil secondary voltage arcing to
>inappropriate places before it gets to the spark plugs.
Well, here's the patient's medical history:
- New coil Thursday night. Problem returned after 10 minutes of
driving, required 10 minutes of sitting and trying to start,
then car ran for about 20 minutes at which time I arrived home.
- New points, condensor, added insulation to ground wire inside
distributor Saturday morning. On the positive side, it was quite
rewarding to have taken the distributor out of the car, disassembled
it, cleaned it, reassembled it, reinstalled it, and have the car start
instantly on the first turn of the key. On the negative side, the
car ran for about three minutes before shutting down. Again, fuel
is visible in the fuel filter and the coil is still getting hot. (For
what it's worth, the mechanical aspects of the distributor appear to
be quite good: I have NEVER seen such steady timing on any car I've
checked. There is NO deviation from the indicated timing position,
unless I rotate the distributor by hand.)
- New cap, rotor, plug and coil wires, spark plugs on Saturday afternoon.
The car ran for about 10 minutes, both in the driveway and on a short
road test. It appeared to have solved the problem. I also pulled the
appropriate fuse from the fusebox, noted that the connectors were fairly
loose, so I pressed them together to improve their grip, reinstalled
the fuse, and then proceeded with the aforementioned road test.
- The problem returned Sunday. The car ran for about five minutes, then
stopped. After about five minutes the car started again, ran for about
two minutes, and stopped. It then took about five minutes to start it
again, it ran for maybe two minutes and shut off. I was close to home
so I pushed it into the driveway.
The only components now that I have not replaced are the white wire in the
primary circuit leading from the #2 terminal of the ignition switch through
the tachometer to the + terminal of the coil and the white-black wire from
the - terminal of the coil to the distributor. As an additional clue, Mr.
Holmes, note that when the engine ceases to fire, the tachometer continues
to register engine speed and the alternator light does not come on until
the engine speed drops below 600 RPM. (Shall I install a new wire running
from the - terminal of the coil to the distributor? I'll do that tonight.)
Wild guess: Would corrosion, grease, road grime etc. on the starter solenoid
terminals cause sufficient resistance to add this kind of load to the ignition
circuit? And while I'm at it, I have been trying to remember Ohm's Law and
I can't recall the mathematical operation on the right hand of the equation
when you've got I on the left and R & V on the right. I seem to remember
that it's multiplication (dammit Jim, I'm a graphics geek, not a hardware
geek!), in which case a sporadic increase in the resistance of that circuit
should result in a corresponding increase in the current, which would heat
up the coil and also make things stop working.
Now for the punch line: I've decided to (*GASP*) take the car in to a shop
to have them trace the wiring. The shop in question is Charlie Rockwell's,
though, who knows what he's doing. (He also has smog equipment and I will
get a certificate while I'm there.) At this point, I need the car more than
I need the satisfaction of a job well done. (Though I can take pride in the
fact that the car's running extremely well before it sputters to a halt. :-)
--Scott
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