Opel 1900 1973, Service Manual, Page: 43 / 625

22 1973 OPEL SERVICE MANUAL
3. Start engine and disconnect a wire from a spark
plug. Read output voltage of disconnected spark
plug circuit. Reading should exceed 20 KV
volts).
C H E C K D I S T R I B U T O R
1. Clean distributor cap and inspect it for cracks or
tracking. Inspect inner segments for erosion and
outer sockets for corrosion.
2. Clean and inspect ignition wires. Make sure resist-
ance of each wire is less than 10,000 ohms. Replace
any defective spark plug boots or distributor
nipples. See paragraph
3. Inspect breaker points and replace if necessary.
Adjust breaker point gap to inch with rubbing
block on peak of cam lobe or check dwell and adjust
if not 50 degrees plus or minus 3 degrees. 4. Check
dwell variation by reading dwell at idle and at 3000
RPM. Dwell must not vary more than 3 degrees.
Excessive variation means distributor shaft, cam or
breaker plate are worn or damaged--overhaul dis-
tributor and replace defective parts.
5. Check distributor condenser for a minimum series
resistance and insulation leakage. Check for a
capacity between
and microfarads.
6. Check total advance (centrifugal and vacuum) at
2500 engine RPM using a timing light having a dial
for reading advance.
(a) The timing marks are aligned with both the
vacuum advance and the vacuum retard hoses dis-
connected and plugged.
Engine idle should be 900 RPM.
(b) Reconnect vacuum hoses. Run engine at
RPM and adjust knob until timing marks are
aligned. Read advance on dial. Maximum centrifugal
advance should
be
between 28-32 degrees.
7.
If
total advance is out of specifications, check
centrifugal advance only, at
RPM.
and plug all vacuum hoses. Maximum vacuum ad-
vance should be l-5 degrees at 4.5-5.0 in. hg.
8. Replace centrifugal or vacuum advance parts as
required to bring distributor total advance within
specifications.
9. Check operation of vacuum retard unit (rear unit)
by
making sure timing marks are aligned with
vacuum hoses disconnected and at slow idle (700
RPM). Then connect vacuum hose to vacuum retard
unit (rear unit). Timing ball should move in a
direction (upward).
SPARK PLUGS
1. Remove spark plugs. If electrodes are badly worn,
discard plugs. If inner or outer porcelain is cracked
or broken, discard plugs.
2. Note color and general appearance of inner end of
spark plug. Brown to grayish tan deposits and slight
electrode wear indicate correct spark plug heat
range. Plugs having this appearance may be cleaned,
regapped,
tested and reinstalled.
3. Clean spark plugs in a sand blast type cleaner.
Clean only enough to remove deposits, not enough to
wear away porcelain. If deposits are too hard to
remove or if porcelain is glazed, discard plugs.
4. After cleaning spark plugs, clean tiring surfaces of
electrodes with a line file.
5. Test cleaned spark plugs on a pressure tester by
comparing spark of the used plugs with that of a new
plug. Install tested plugs, using new
gaskets.
6. If removed spark plugs have excessive carbon foul-
ing and if the car will be driven mostly at low speeds
in city driving, it is advisable to replace plugs with
a hotter plug,
7. If removed plugs show rapid electrode wear or
inner porcelain breakage at low mileage. Check for
a vacuum leak such as a poor manifold to head fit.
8. spark plugs carefully (new or cleaned) using
a round wire feeler gage.
Figure Distributor Installation