Timing chain marks needed

Tiny
DONALD FRESHOUR
  • MEMBER
  • 2007 CHEVROLET SILVERADO
  • 4.8L
  • V6
  • 2WD
  • AUTOMATIC
  • 145 MILES
Can you please tell me the marks for the timing chain?
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Thursday, May 28th, 2020 AT 10:02 PM

7 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Good morning,

I attached a picture for you of the marks. The cam gear, the mark is at 6 o'clock. The crank gear mark is at 12 o'clock. Let me know if you have any other questions. Check out the diagrams (Below). Please let us know if you need anything else to get the problem fixed.
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Friday, May 29th, 2020 AT 3:53 AM
Tiny
CATTHELYNN
  • MEMBER
  • 1 POST
  • 2006 CHEVROLET SILVERADO
  • 6.0L
  • V8
  • 2WD
  • AUTOMATIC
  • 200,000 MILES
Hi,
I'm trying to change my timing chain and sprockets but when the camshaft and crankshaft marks are at the 6 and 12 o'clock position the #1 piston is not at the compression TDC. When it is at TDC the camshaft and crankshaft are both at the 12 o'clock position. How do I fix this? Or when removing the chain and camshaft sprocket does it matter if the #1 piston is at the compression TDC? Everything I've read says it does. Help.
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Friday, August 21st, 2020 AT 12:32 PM (Merged)
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Hi.

You are to set the crank and cam so they line up 6 and 12 o'clock. Don't worry about #1 TDC. The crank has a key on it and the cam has a specific bolt pattern to ensure they are timed.

You really only need to worry about #1 TDC when installing a distributor if equipped. This way you get the #1 plug to fire on TDC.

Due to having the crank key way and bolt pattern, it allows you to only align them one way and you need to have them lined up when removing the chain and sprockets and then do not make a crank or cam rotation with the chain off or you will be out of time and the engine will be damaged. It is okay if they move a little because you can just line them back up but if they make a rotation then you will be in trouble.

Here is the detail about how to do it. As you see the book doesn't mention anything about TDC.

Let me know if you need anything else. Thanks
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Friday, August 21st, 2020 AT 12:32 PM (Merged)
Tiny
NEVADA3.0
  • MEMBER
  • 2 POSTS
  • 2000 CHEVROLET SILVERADO
Engine Performance problem
2000 Chevy Silverado 6 cyl Two Wheel Drive 160000 miles

This truck missed on multiple cyl, updated injectors. The cam retard timing reads -16 on my scanner. Is it supposed to be 0 + or - 2? Just doesn't respond well when under heavy acell
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Friday, August 21st, 2020 AT 12:32 PM (Merged)
Tiny
MERLIN2021
  • MECHANIC
  • 17,250 POSTS
Is it pinging? One of the TSB's (tech bulliten) Is for the PCM ground strap on the back or front of the cylinder head. Clean it up by removing the strap, clean it, and the grounding point on the head. Any codes?
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Friday, August 21st, 2020 AT 12:32 PM (Merged)
Tiny
NEVADA3.0
  • MEMBER
  • 2 POSTS
The ground strap end was replaced, the truck doesn't ping it just doesn't accelerate as fast as it should
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Friday, August 21st, 2020 AT 12:32 PM (Merged)
Tiny
MERLIN2021
  • MECHANIC
  • 17,250 POSTS
On 4.3 litre engines it may be necessary to remove the distributor and elongate the hold down bolt hole to allow for adjustment. The hold down is fixed to the distributor. In many cases the adjustment is wrong from factory.
Inspection 1. With ignition off, connect scan tool to Data Link Connector (DLC). Start engine and allow it to reach normal operating temperature. 2. Increase engine speed to more than 1000 RPM. Using scan tool, monitor CAM RETARD OFFSET. If camshaft retard indicates zero degrees plus or minus 2 degrees, distributor is properly adjusted. Procedure is complete. If camshaft retard is not zero degrees plus or minus 2 degrees, see ADJUSTMENT. Adjustment 1. Turn ignition off. Slightly loosen distributor hold-down bolt. Start engine. Increase engine speed to more than 1000 RPM. 2. Using scan tool, monitor CAM RETARD OFFSET. To adjust for a negative reading, rotate distributor counterclockwise. To adjust for a positive reading, rotate distributor clockwise. 3. Continue to adjust as necessary until zero degrees plus or minus 2 degrees is attained. Turn ignition off. Tighten distributor hold-down bolt to 25 ft. Lbs. (34 N.M). Start engine. Increase engine speed to more than 1000 RPM. Using scan tool, verify camshaft retard offset adjustment. NOTE: Camshaft retard offset reading will not be accurate with engine speed less than 1000 RPM. Page 1 of 1 3/22/2010 .
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Friday, August 21st, 2020 AT 12:32 PM (Merged)

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