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IGNITION TIMING
Specifications
Application/Qualifier
Transmission
Set Timing Spec (Min-Max) Crankshaft Degrees
Set Timing Spec (Min-Max) RPM
Auto Trans Gear
Check Timing Spec (Min-Max) Crankshaft Degrees
Check Timing Spec (Min-Max) RPM
Footnote
GS
Auto Transmission
-
-
Parking
0 - 10
-
(1)(2)
Manual Transmission
-
-
-
0 - 10
-
(1)(2)
Footnotes
Note-ID
Description
1
Reference only, timing is not adjustable.
2
Check timing with a suitable timing light or scan tool. If timing is not within specified range, further diagnosis of the engine management system is necessary.
Static timing (distributor setting) on this vehicle requires a stroboscopic timing light and following the proper setting procedure. If you do not have access to a Shop Manual for this vehicle, I recommend consulting a GM dealer for static timing adjustment instructions.
I am not sure why you would need a diagram for the ignition timing?
I have no access to data on this computer but mostly even the best data books simply provide the written location of the marks and the basic, stroboscopic and a few auto-advance details. In some cases there must be some preparation to ensure accurate timing. Try the link below
the timing marks are on the crankshaft pulley. slightly loosen the distributor and use a stroboscopic timing light to pulse the correct setting...adjust distributor anti clockwise or clockwise to set. I f you are still running contact breakers please ensure these are set before doing timing.
Hi Eric, Vehicles fitted with distributors using points (contact breakers) and condensers, which I believe is the case with your vehicle use a dwell angle setting. Initial setting is carried out with a feeler gauge. After replacing points and condenser, turn the engine until the rubbing block on the points is at the highest point against the distributor cam (at the centre of the distributor). Set the gap at 16 thousands of an inch or 0.45 mm. Inspect the front crankshaft fan belt pulley to identify the timing marks. Paint a white mark onto the pointer (fixed to the timing cover) and rotate the engine by hand until you see the timing scale on the crankshaft pulley. mark with white paint at 10 degrees BTDC and align the pulley to the pointer and set the points in the distributor (by releasing the locking bolt of the distributor body) to be at the exact point when it begins to open. Replace the cap and connect a stroboscopic timing light, start the engine and let it idle at normal idle speed and reset the ignition timing to the same marks painted with white paint. Don't forget to take all safety requirements seriously as you will be working on a running engine. Regards John
Hi Lucas, What engine is fitted? If the engine is petrol, the rattling sound you have heard could well be an effect named 'pinking.' Its usually caused by the ignition timing being out of adjustment and related to the octane rating of the fuel. The ignition timing is set with a stroboscopic timing light. the ignition timing is set at 10 degrees before top dead center. Regards John
Hi Mosso, Yes it definitely could be. Reset it with a stroboscopic timing light. It could also be leaking vacuum hoses so check them all for tightness of fit and make sure there are not any which are damaged. Regards John
Not sure why he would tell you the engine has to be taken out to set the timing. If he means the timing belt is wore out and needs to be changed, you can change the belt without pulling the engine. The engine cant be timed. It is set automatically.
Timing INSPECTION AND ADJUSTMENT Distributor Not Removed EXCEPT MOTRONIC MODELS NOTE: Ignition timing on late model vehicles is constantly being adjusted by the Digital Motor Electronics (DME) engine control system. No manual timing adjustment is necessary or possible.
In order to adjust the ignition timing dynamically, the engine must be at operating temperature and running at a specified rpm (see the Tune-Up Specifications chart). A stroboscopic timing light and tachometer are needed for this operation.
Disconnect and plug the vacuum line(s) at the distributor.
Attach a timing light and tachometer according to the manufacturer's instructions.
Raise the idle speed to that listed in the Tune-Up Specifications chart under Ignition Timing.
With the idle speed adjusted to the proper rpm direct the stroboscopic timing light beam straight down through the opening in the flywheel housing flange adjacent to the starter, and align the steel ball pressed into the flywheel with the timing mark on the flywheel housing.
Loosen the distributor hold-down bolt and rotate the distributor as necessary.
After the adjustment has been made, tighten the hold-down bolt and recheck the timing at the specified rpm to make sure that the setting was not disturbed during tightening.
MOTRONIC MODELS
Although the timing on vehicles equipped with the Motronic control unit cannot be adjusted, the timing can still be checked.
On cars with the Motronic control unit, the only cure for improper timing is to replace the control unit. Also, timing must be within a certain range, as the computer changes the timing slightly to allow for various changes in operating condition. In other words, the timing does not have to be right on the mark, but anywhere in the specified range.
To check the timing, proceed as follows:
Look up the control unit number found on the casing of the assembly. If you vehicle is a 3, 5 and 6 series vehicles, the control unit unit is located in the glove box. If your vehicle is a 7 series, the control unit is in the right side speaker cutout. Find the unit number on the underside of the assembly and then cross reference the number to the corresponding number on the Computer Controlled Ignition Timing Chart.
The engine should be at normal operating temperature. The rpm level should be within the specified range as well.
Connect a tachometer and a timing light to the engine. Start the engine and check the rpm. If it is not correct see the appropriate checks under Idle Speed and Mixture Adjustment. Operate the timing light to see if the timing is within the range specified on the chart. If it is significantly outside of the specified range, the control unit must be replaced.
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