1973 OPEL GT-R gas mileage

LUBRICATION AND MAINTENANCE OC-11
Throttle Linkage
Check for damaged or missing parts, interference or
binding. Any deficiencies should be corrected with-
out delay.
Headlights
Check for proper aim. Correct as necessary. More
frequent checks should be made if oncoming motor-
ists signal when you are already using your low
beams, or if illumination of the area ‘ahead seems
inadequate.
Underbody
In geographic areas using a heavy concentration of
road salt or other corrosive materials for snow re-
moval or road dust control, flush and inspect the
complete under side of the car at least once each
year, preferably after a winter’s exposure. Particular
attention should be given to cleaning out underbody
members where dirt and other foreign materials may
have collected.
EMISSION CONTROL MAINTENANCE
Thermostatically Controlled Air Cleaner
Inspect installation to make certain that all hoses and
ducts are connected and correctly installed. Also,
check valve for proper operation.
Carburetor Choke
Check choke mechanism for free operation. A bind-
ing condition may have developed from petroleum
gum formation on the choke shaft or from overtight-
ening of air cleaner clamp. Also check electric choke
terminal connections and fuse.
Timing, Dwell and Distributor
Adjust timing and dwell accurately as outlined under
Tune-Up in Group 6 at the first 4 months or 6,ooOmiles of operation, then at 12 month or
12,OQO mile
intervals. Adjustments must be made with test equip-
ment known to be accurate.
Replace distributor points every 12 months or 12,000
miles and carefully clean and inspect the complete
distributor cap to prevent misfiring and deteriora-
tion.
Carburetor and Idle
SpeedTorque carburetor attaching bolts and/or nuts to 12
ft.lbs. to compensate for compression of gasket atiirst 4 months or 6,000 miles of vehicle operation.Adjust idle speed to specifications with known accu-
rate equipment.
Proper functioning of the carburetor is particularly
essential to control of emissions. Correct mixtures
for emission compliance and idle quality have been
preset by Opel. Plastic idle mixture limiters have
been installed on the idle mixture screw, idle air
screw, and throttle stop screw to preclude unauthor-
ized adjustment. The plastic caps on the idle mixture
screw and the idle adjustment screw must be
removed to perform an idle speed adjustment. The
plastic cap on the throttle stop screw is not to be
removed unless some major carburetor repair or re-
placement which affects the throttle stop screw ad-
justment has been necessary.
Carburetor Fuel Inlet Filter
Replace filter at 12 month or
12,OCO mile intervals
or more often if clogged.
Spark Plugs
Replace at
6,ooO mile intervals when operating with
leaded fuels or at 12,000 mile intervals when using
unleaded fuels. Use of leaded fuels results in lead
deposits on spark plugs and can cause misfiring at
mileages less than
12,OilO miles. Where misfiring oc-
curs prior to
6,ooO miles, spark plugs in good condi-
tion can often be cleaned, tested and reinstalled in an
engine with acceptable results.
Spark Plug Wires
Inspect spark plug wires for evidence of checking or
cracking of exterior insulation and tight fit in the
distributor cap and at the spark plugs. Exterior of
wires should be cleaned, any evidence of corrosion
on ends removed and wire replace if deteriorated.
Positive Crankcase Ventilation System
The PCV metered orifice should be cleaned at 12,000
mile intervals under normal use, and at 6,000 mile
intervals when the vehicle is used under the follow-
ing conditions: driving in dusty conditions, extensive
idling, trailer pulling and short trip operation at
freezing temperatures (engine not thoroughly
warmed-up).
Evaporation Control System
Check all fuel and vapor lines and hoses for proper
connections and correct routing as well as condition.
Remove canister and check for cracks or damage.
Replace damaged or deteriorated parts as necessary.
Replace filter in open end of canister at 24month/24,000 mile intervals.

lC- 22 1973 OPEL SERVICE MANUAL j
3. Start engine and disconnect a wire from a spark
plug. Read output voltage of disconnected spark
plug circuit. Reading should exceed 20 KV
(20,poO
volts).I
CHECK DISTRIBUTOR
!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
capnipples. See paragraph lC-12.
3. Inspect breaker points and replace if necessary.
Adjust breaker point gap to
,016 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
.15 and .20 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
3600RPM 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
2500 RPM. Discon+ectand 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 first 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 retard
direction (upward).
CHEICK SPARK PLUGS1. 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, AC43FS.
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.
Clap spark plugs carefully (new or cleaned) using
a
,030 round wire feeler gage.IC6
Figure lC-6 Distributor Installation