Timing problems.

[Back N Black]

I bought this OEM style replacement Summit Racing distributer for my 1996 Vortec 350:

https://m.summitracing.com/parts/sum-850098

Prior to installing it, I found TDC, and pointed the rotor to the number 1 plug wire on the cap. I checked my timing, and I am 18-20 degrees advanced. I spent 5 1/2 - 6 hours trying to adjust it yesterday. I was trying to back the timing down by pulling the distributer up, rotating it backwards a gear and putting it back in. When I try to do this, the gear on the distributer does not line up properly to allow me to re-install the distributer. I also have a Comp Cams Xtreme Fuel Injection cam in the motor, and that was properly lined up when we installed it. What can I be doing wrong here? Once I have it dialed in and running correctly, I will be ordering a mail order a tune from you. I'm wondering if I have to leave the distributer where it is, and have the tune compensate for the timing. Can you pull that much timing out with your tune? I mean, I know I need to get it pretty close to proper timing manually, but the closest I can seem to get it, is still pretty well advanced. Any help will be greatly appreciated! Thank you for your time.

Untimely confused . . .

 

[Chizzychase]

I think you may be in the wrong thread buddy.

 

[SUBURBIAN]

You really need a scantool like a GM Tech2 to set the base timing in an L31.

TEST PROCEDURE
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 PROCEDURE


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:
4.1. To compensate for a negative reading, rotate the distributor in the counterclockwise direction.
4.2. 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 3 Nm (25 lb. ft.).
Start the engine, raise engine speed to 1000 RPM and recheck Camshaft Retard Offset.

Procedure A

Remove or Disconnect



Make sure the ignition switch is "OFF."
Spark plug and coil leads from the distributor cap.
Three wire hail effect switch plug from the base of the distributor.
Two screws holding the distributor cap to the housing.
Distributor cap.
Use a grease pencil to note the position of the rotor segment in relation to the distributor housing. Identify the mark with a 1.
The distributor housing and intake manifold should also be marked with a grease pencil for proper alignment when reinstalling.
Mounting clamp hold down bolt.
Distributor.
As the distributor is being removed from the engine, you will notice the rotor move in a counter-clockwise direction, 42°. This will appear as slightly more than one clock position. Noting the position of the rotor segment, by placing a second mark on the base of the distributor, will aid in achieving proper rotor alignment during distributor installation. Be sure to identify the second mark on the base with the number 2.
Install or Connect

Distributor Alignment Indicator








If the original distributor is to be replaced, rather than repaired, remove the new distributor cap. Using a grease pencil, place two marks on the new distributor housing in the same location as the two marks on the original housing.
When installing the distributor, align the rotor segment with the number 2 mark on the base of the distributor. Guide the distributor into place, making sure the grease pencil marks on the distributor housing and the intake manifold are in line. As the the distributor is being installed, you will notice the rotor will move in a clockwise direction, 42°. ONCE THE DISTRIBUT0R IS COMPLETELY SEATED, the rotor segment should be aligned with the number 1 mark on the base. If the rotor segment is not aligned with the number 1 mark, the gear teeth of the distributor and camshaft have meshed one or more teeth out of time. To correct this condition, remove the distributor and re-install it following the procedure at step B.
Distributor cap and mounting screws. Do not overtighten the screws as the boss may strip.
Distributor mounting clamp and tighten to proper torque. Tighten
Distributor clamp and bolt to 27 Nm (20 lbs. ft.)
Distributor cap screws to 4.5-5.0 Nm (40-45 lbs. in.)
Three wire hall effect switch connector to base of the distributor.
Spark plug and coil leads to the distributor cap.
If a check engine light is illuminated after installing the distributor and a DTC P1345 is found, the distributor has been installed incorrectly. You now must refer to procedure; B or proper distributor installation.



Procedure B

Remove or Disconnect



Make sure the ignition switch is "OFF."
Bring the engine up to Top Dead Center (TDC) of cylinder number 1. Make sure it is on the compression stroke.
Remove the distributor cap screws and cap to expose the rotor.
Rotor Location








Align the pre-drilled indent hole in the distributor driven gear with the white painted alignment line on the lower portion of the shaft housing. The rotor segment should point to the cap hold area as shown in the illustration.
Using a long screw driver, align the oil pump drive shaft in the engine in the mating drive tab in the distributor.
Guide the distributor into place, making sure the the spark plug towers are perpendicular to the center line of the engine.
Installed Rotor Position








ONCE The DISTRIBUTOR IS FULLY SEATED, the rotor segment should be aligned with the pointer cast into the distributor base. This pointer will have a "8" cast into it, indicating the distributor is to be used in a 8 cylinder engine. if the rotor segment does not come within a few degrees of the pointer, the gear mesh between the distributor and camshaft may be off a tooth or more. If this is the case, repeat the procedure again to achieve proper alignment.
Install or Connect



Cap and mounting screws. Do not overtighten as the boss may strip.
Distributor mounting clamp and tighten to proper torque. Tighten
Distributor clamp and bolt to 27 Nm (20 lbs. ft.)
Distributor cap screws to 4.5-5.0 Nm (40-45 lbs. in.)
Three wire hall effect switch plug to base of distributor.
Spark plug and coil leads to the distributor cap.
If a check engine light is illuminated after installing the distributor and a DTC P1345 is found, the distributor has been installed incorrectly.

 

[drakon543]

Well between any searching you have already done and suburban's information you already know you need to get the timing to 0 + or - 2. Judging by your current issue your trying to bump the dizzy back teeth but your forgetting to turn oil pump shaft so it also lines up. If you look at the bottom of the distributor it has a slot that needs to go over the oil pump shaft. Also as suburban mentioned you need a scan tool to check the timing in these trucks a timing light wont help you at all.

 

[SUBURBIAN]

Right. On an L31, you don't set the timing, you set the cam retard.

 

[muldoon]

You do not have to pay the dealer shop labor for the Tech 2 to set the timing if the engine is running, even if running poorly. If the timing, or cam retard is off, you should be getting a message on the DIC and a trouble code can be pulled with any low-tech scan tool. First, you need a reference point. Make a pointer out of a yardstick or 1/4" wood slat so you can make a reference mark on a piece of masking tape put on the firewall, when the pointer is clamped securely to the distributor. Then turn the distributor so the mark moves about 1/8" in one direction. Then clear the codes and start the truck. What you're trying to do is get the distributor turned to where there is no error message or error code found on your scan tool. If you're turning the distributor so the marks are moving, say, to the left and the engine is running rougher, rather than smoother, go back to the original reference point and start moving the pointer in the other direction. Eventually all will fall into place, engine running right and no codes and you can go and spend the one or two hours the dealer would have charged you and find a better use for the cash.

 

[drakon543]

^ ive done a few without a scan tool and it is definitely possible it just might take you a while. Especially if you have it set too far off to turn it far enough to get it timed. The distributor can only be rotated so far before the cap hits the intake. But again if you need to jump a tooth you will likely need to rotate the oil pump shaft in the direction your trying to go or it will just keep trying to go back on the same teeth.

 

[Back N Black]

Well between any searching you have already done and suburban's information you already know you need to get the timing to 0 + or - 2. Judging by your current issue your trying to bump the dizzy back teeth but your forgetting to turn oil pump shaft so it also lines up. If you look at the bottom of the distributor it has a slot that needs to go over the oil pump shaft. Also as suburban mentioned you need a scan tool to check the timing in these trucks a timing light wont help you at all.

I think my problem was that we didn't turn the oil pump shaft. I suspected that would need to be done in order for the dizzy to fall into place, but the person I asked about this said I shouldn't have to. I knew I was correct on this. This is my first engine build though.

It's running like shit right now, but the timing is only one of the issues. I also have three codes for O2 sensors. When I got the truck, it had bad intake gaskets. Had quite a bit of water in the pan. My uncle said that if any water got to the O2 sensors, that could have caused them to fail. So, it looks like I'll need to pull the dizzy, back it up a gear, adjust the oil pump shaft, and change both O2 sensors. That may get me where I need to be. Atleast I hope.

 

[drakon543]

For future reference unless you get one that someone has already messed up the timing with an improper dizzy install. Always put plenty of markings on the old distributor when you pull it out so you can be sure to put the new one back in the same place.

 

[Back N Black]

Very good point sir! Just finding all the bolts and where they came from was a task after it had been apart for so long.