Try this for basic spark troubleshooting:
1. Remove the distributor cap
2. Remove the high voltage wire
from the coil to the distributor cap
3. Remove #1 spark plug wire from the
distributor cap and insert it into the
coil.
4. Remove #1 spark plug from the engine
and clamp it to grounded metal where
it is easy to see the electrode.
5. Connect the other end (see step 3)
of #1 spark plug wire to this spark
plug.
6. Crank the engine over stopping with the
points closed.
7. Turn the key to the "ON" position.
8. Use a PLASTIC device to manually open
the points. DO NOT USE ANY METAL DEVICE
to do this job. YOU WILL BE SHOCKED.
THE VOLTAGE AT THE OPEN SIDE OF THE POINTS
IS MUCH HIGHER THAN THE 6 VOLTS IN THE
SYSTEM WHEN THE ELECTRICAL FIELD IN THE
COIL COLLAPSES. Even if you don't get
bit, using a metal tool may provide a
path for current to continue to flow,
preventing the spark from occurring.
A plastic ink pen will be a good tool
to use.
9. When the points open there should be a
nice blue spark at the plug.
10. If you have a DC voltmeter you should see:
a. with the points open the "wire" side
of the points, the "+" and the "-"
side of the coil should be battery voltage
(6V in your case) measured to ground
b. with the points closed the "wire" side
of the points and the "-" side of
the coil should be zero volts. Even
a few tenths of a volt indicate
dirty/burned points.
c. with the points closed the "+" side of
the coil should be battery voltage
(6V in your case) measured to ground.
Even a few tenths less than battery
voltage indicates high resistance
somewhere in the supply path.
Using this method allows you to evaluate the
ignition without actually having the engine
running with associated noise and heat.
Any decent auto parts store should be able to
test your coil for you if the steps above do
not point out a problem.
-----Original Message-----
From: Bruce Marshall [mailto:k1aj@bellatlantic.net]
Sent: Monday, October 29, 2001 10:20 AM
To: oletrucks@autox.team.net
Subject: [oletrucks] basic question
I have just completed the install of a 'new' Chevy 216 engine in my '51
Chevy 1/2 ton p/u.
Yesterday afternoon we cranked it over for the first time after hooking
up
the battery. The engine turns (it turned by hand when we had it on the
engine stand) but we have no spark at the plugs. We get spark at the
points
and at the coil output although the spark from the coil looks rather
weak.
Rotor is installed (didn't forget that) and the cap is good I think.
The
plug wires "look" OK but should I install a new set?
The engine turns pretty slowly and we suspect the battery might be NG
even
though it was new 4 years ago and has been on one of those battery
tender
devices.
Bruce Marshall
Boston, MA
oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
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