Distributor Timeing Adjustment

[rickmac]

hi all i have checked readout on my 96 silverado with my ob2 reader it seems the timeing is retarded so do i just undo clamp bolt and twist until corect 0 to-2 as in chiltern or is there more to it

350 engine runs ok

[rodram]

NO.. I would not do that..

 

... just turning the dist cap will just be a shot in the dark timing setting .. the process is more complicated

 

.. to set timing on a 96-99 Vortec engine you need to have a scanner that can read the cam retard .. then you need to do some specific things and set the timing for a specific rpm...

 

.. to me, that means get a mechanic with the right tools to check/adjust the timing...

[Badass69]

If you have a scan tool that shows the cam retard offset value you can set the distributor position. If you do there is nothing to setting the timing on these trucks. The specific rpm mentioned is just 1000 rpm and that is all. Here are some instructions that I found that are from GM.

 

 

Setting Timing

Camshaft Retard Offset Test

The ignition timing cannot be adjusted. The distributor may need adjusting to prevent crossfire. To insure proper alignment of the distributor, perform the following:

 

With the ignition OFF, install a scan tool to the DLC.

Start the engine and bring to normal operating temperature.

 

Important

Cam Retard Offset reading will not be accurate below 1000 RPM

 

 

Increase engine speed to 1000 RPM.

Monitor the Cam Retard Offset.

If the Cam Retard indicates a value of 0° ± 2°, the distributor is properly adjusted.

If the Cam Retard does not indicate 0° ± 2°, the distributor must be adjusted.

Adjusting Camshaft Retard Offset

 

 

 

 

With the engine OFF, slightly loosen the distributor hold down bolt.

Important: Cam Retard Offset reading will not be accurate below 1000 RPM

 

 

Start the engine and raise engine speed to 1000 RPM.

Using a scan tool monitor Cam Retard Offset.

Rotate the distributor as follows:

To compensate for a negative reading, rotate the distributor in the counterclockwise direction.

To compensate for a positive reading, rotate the distributor in the clockwise direction.

Repeat step 4 until 0° ±2° is obtained.

Turn the ignition OFF.

Tighten the distributor hold-down bolt to 3N·m(25 lb. ft.).

Start the engine, raise engine speed to 1000 RPM and recheck Camshaft Retard Offset.

[rickmac]

If you have a scan tool that shows the cam retard offset value you can set the distributor position. If you do there is nothing to setting the timing on these trucks. The specific rpm mentioned is just 1000 rpm and that is all. Here are some instructions that I found that are from GM.

 

 

Setting Timing

Camshaft Retard Offset Test

The ignition timing cannot be adjusted. The distributor may need adjusting to prevent crossfire. To insure proper alignment of the distributor, perform the following:

 

With the ignition OFF, install a scan tool to the DLC.

Start the engine and bring to normal operating temperature.

 

Important

Cam Retard Offset reading will not be accurate below 1000 RPM

 

 

Increase engine speed to 1000 RPM.

Monitor the Cam Retard Offset.

If the Cam Retard indicates a value of 0° ± 2°, the distributor is properly adjusted.

If the Cam Retard does not indicate 0° ± 2°, the distributor must be adjusted.

Adjusting Camshaft Retard Offset

 

 

 

 

With the engine OFF, slightly loosen the distributor hold down bolt.

Important: Cam Retard Offset reading will not be accurate below 1000 RPM

 

 

Start the engine and raise engine speed to 1000 RPM.

Using a scan tool monitor Cam Retard Offset.

Rotate the distributor as follows:

To compensate for a negative reading, rotate the distributor in the counterclockwise direction.

To compensate for a positive reading, rotate the distributor in the clockwise direction.

Repeat step 4 until 0° ±2° is obtained.

Turn the ignition OFF.

Tighten the distributor hold-down bolt to 3N·m(25 lb. ft.).

Start the engine, raise engine speed to 1000 RPM and recheck Camshaft Retard Offset.

 

thanks for the info i will check my scan tool is readingcam offset

[VRSCA1]

Generally when this adjustment starts to go negative over -5 degrees a fault code will set.Most times the distributor drive gear becomes worn out.The distrubutor drive gear teeth become "knife Edged" is the way it is usually refered to.You may want to consider pulling the distributor for an inspection of the drive gear.

[HawkScot]

I emailed the developer and made sure my vehicle was included, then purchased the unit, installed software, connected obd-2 to laptop and vehicle, followed instructions above to check offset. It was dead on (0, I had replaced intake gaskets and distributor gear).

 

http://www.obd-2.com/