Timing
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Timing
ok, so i have been trying to time my car now for a bit. Blue link on the intake mark, purple on the exhaust. get it tight with the tensioner and everything seems good in the hood.
But...someone told me that you need to rotate you crank 2 times and still have the marks line up. This is what i am having trouble with.
I have done this now about 6 times, get it set do the rotations and the marks are always off by 6 links. Now I was thinking that there wasn't enough tension in the chain, but i go in reverse direction the marks will all line up again.
anyone?
But...someone told me that you need to rotate you crank 2 times and still have the marks line up. This is what i am having trouble with.
I have done this now about 6 times, get it set do the rotations and the marks are always off by 6 links. Now I was thinking that there wasn't enough tension in the chain, but i go in reverse direction the marks will all line up again.
anyone?
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From: SEWELL ,NJ
THE REASON THAT EVERYTHING LINES UP WHEN YOU GO IN REVERSE IS BECAUSE YOU AR TRANSFERING THE SLACK IN THE CHAIN FROM ONE SIDE TO THE OTHER, A LITTLE TIP IS TO SET THE CRANK GEAR ONE TOOTH BACK AND SET YOUR CAMS, THIS WAY AS THE SLACK IS PULLED ALL YOUR MARKS WILL LINE UP 
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From: No where man
Well the marks WILL NOT align after 2 rotations, (like a SBC for instance) Due to the chain to gear ratios involved IIRC it will take something like 44 revolutions to realign the links/marks!
The basic cam, timing chain and sprocket installation sequence goes something like this:
1. Start by making sure the engine is at a "safe" position with all pistons "down bore" The ideal spot is 90 degrees before TDC when ALL piston will be 1/2 way down bore. Use the spline on the crank snout as a guide. When this spline is at 12 o'clock you are at TDC on cylinder 1 and 4. So by placing the spline at 9 o'clock it will be 90 degrees BTDC. This insures that the valves absolutely CANNOT hit the pistons. The cams should still be removed when you do this so nothing will be damaged. If you turn the engine with the chain removed and the cam/s installed, you risk bending a valve as the Ecotecs are ALL "interference" design. *Hint* The engine will be much easier to turn if the spark plugs are removed. GM has a special socket that fits into the spline for turning the engine at the crank snout, but it's jsut as easy to reinstall the crank pulley bolt.
2. With the engine at this safe position and all the lash adjusters and roller followers in place install the cams (least loaded position) install all the cam caps in their original locations (they are marked) then torque all the cam caps gradally and evenly to 89 lb in (small head) and 18 lb ft (large head). You will need to apply some sealer to the large cap at the end of the cam (which cam depends on which Ecotec engine)to prevent an oil leak.
MAKE SURE ALL OF THE ROLLER FOLLOWERS HAVE STAYED PROPERLY PERCHED ON THE VALVE- THEY TEND TO FALL OFF WHILE TORQUING!.
Next install the sprockets onto the cams. Hand tighten the bolts at this time only as they are torque-to-yield type. (These must be NEW bolts as the MUST NOT be reused or they WILL come loose= disaster! ) Hand tighten means using a wrench or socket so the items are tight enough that they wont move, don't mistake this for "finger" tight (which I've seen happen here as a common error that screws things up later)
3. Confirm the engine is STILL in the "safe" position, then use a large open end wrench (24mm) to rotate the cams (using the hex flats between the lobes) until the the cam gear PIP (Part In Position) marks are at 10 o'clock (exhaust= triangle shaped) and 2 o'clock (intake= diamond shaped) Then remove the exhaust sprocket.(Hold the cam with the wrench so the cam does NOT rotate when you remove the bolt)Leave the intake sprocket ON.
4. NOW slowly rotate the engine 1/4 turn up to TDC (spline at 12 o'clock) and install the crank sprocket. At this point the PIP mark on the chain drive should be at approx 5 o'clock. Then drop the chain down from above from the intake side making sure you are on the correct sides of the 2 "bosses" in the block.
*NOTE* DO NOT ROTATE THE CAMS WHEN AT TDC OR THE VALVES WILL HIT THE PISTONS AND BE DAMAGED!
5. Install the chain over the intake gear aligning the "odd" uniquely colored link to the PIP (should still be at 2 o'clock) The "odd" uniquely colored link is colored differently from the other 2 colored links on the chain (there are actually various different colors used depending on year) Work the chain down and around the crank gear ("even" colored mark should align) Drop the tensioner shoe down from above and install the pivot bolt (89 lb in)
6. Work the chain up towards the exhaust cam. A coat hanger works good here to pull the chain up through the head on the exhaust side and support it while you install the movable tensioning shoe. Then after insuring the other to links are still in alignment slip the chain around the exhaust sprocket (aligning the other "even" colored link to the EXH PIP mark) and align the exhaust gear with the cam and install the bolt (Again hand tight only) You MAY NEED to use a 24mm open end wrench to "slightly" rotate the cam against a loaded valve spring so that the sprocket properly aligns and will slip on and fully seat against the cam.
DO NOT INSTALL THE BOLT IN ORDER TO "SUCK" THE SPROCKET ONTO THE CAM OR DAMAGE WILL OCCUR!
7. After confirming once more that the PIP marks are all still aligned, install the RH "fixed" chain guide and tighten these bolts (one through the access hole in the head) to 11 lb ft. Put some thread sealer on the plastic plug and install into the head.
8. Install the upper guide on top of the head between the two sprockets (89 lb in)
9. Separate the halves of the tensioner mechanism and "collapse" the spring loaded mechanism by using a large screwdriver to turn it clockwise in order to "lock" it into a loaded state. (GM has a special tool for this of course) Reassemble the tensioner halves and MEASURE it's entire length. It SHOULD be 2.85" (72mm) or less if you successfully loaded the tensioner.
DO NOT INSTALL A RELEASED CHAIN TENSIONER (GREATER THAN 72MM) INTO THE BORE OR DAMAGE WILL OCCUR.
*Hint if you cant get the tensioner to "latch" into the loaded position PURCHASE A NEW TENSIONER as they come "preloaded"
10. Lubricate the tensioner seal with a bit of engine oil and install into the bore. tighten to 55 lb ft.
11. Next use a wooden dowl (aka broom handle
) or the handle end of a long screw driver, to come down from above and push sharply (bump hard with the palm of you hand) on the curved side of the tensioner shoe (collapsing the tensioner somewhat against the spring) in order to "release" the spring loaded mechanism within the tensioner. You will know if you were successful as the chain will get noticeably tighter.
12. Once again reconfirm the engine is at TDC and that all the PIP marks are STILL in alignment. Then use a 24 mm wrench to hold each cam while you tighten the NEW sprocket mount bolts to 63 lb ft THEN use a torque angle meter/gage to apply an additional 30 degrees of tightness on the bolts.
These are torque-to-yield fasteners so this accuracy is important! DO NOT reuse these bolts as they will NOT be able to hold the sprockets tight enough once they have been torqued even ONCE to their yeild (stretch) point.
*You can now reassemble the front cover and rest of the assembly. On an LSJ now is a good time to install the CAM POSITION SENSOR (aligning the PIP marks on th drive hex and the housing) as it gets timed to TDC as well.
The basic cam, timing chain and sprocket installation sequence goes something like this:
1. Start by making sure the engine is at a "safe" position with all pistons "down bore" The ideal spot is 90 degrees before TDC when ALL piston will be 1/2 way down bore. Use the spline on the crank snout as a guide. When this spline is at 12 o'clock you are at TDC on cylinder 1 and 4. So by placing the spline at 9 o'clock it will be 90 degrees BTDC. This insures that the valves absolutely CANNOT hit the pistons. The cams should still be removed when you do this so nothing will be damaged. If you turn the engine with the chain removed and the cam/s installed, you risk bending a valve as the Ecotecs are ALL "interference" design. *Hint* The engine will be much easier to turn if the spark plugs are removed. GM has a special socket that fits into the spline for turning the engine at the crank snout, but it's jsut as easy to reinstall the crank pulley bolt.
2. With the engine at this safe position and all the lash adjusters and roller followers in place install the cams (least loaded position) install all the cam caps in their original locations (they are marked) then torque all the cam caps gradally and evenly to 89 lb in (small head) and 18 lb ft (large head). You will need to apply some sealer to the large cap at the end of the cam (which cam depends on which Ecotec engine)to prevent an oil leak.
MAKE SURE ALL OF THE ROLLER FOLLOWERS HAVE STAYED PROPERLY PERCHED ON THE VALVE- THEY TEND TO FALL OFF WHILE TORQUING!.
Next install the sprockets onto the cams. Hand tighten the bolts at this time only as they are torque-to-yield type. (These must be NEW bolts as the MUST NOT be reused or they WILL come loose= disaster! ) Hand tighten means using a wrench or socket so the items are tight enough that they wont move, don't mistake this for "finger" tight (which I've seen happen here as a common error that screws things up later)
3. Confirm the engine is STILL in the "safe" position, then use a large open end wrench (24mm) to rotate the cams (using the hex flats between the lobes) until the the cam gear PIP (Part In Position) marks are at 10 o'clock (exhaust= triangle shaped) and 2 o'clock (intake= diamond shaped) Then remove the exhaust sprocket.(Hold the cam with the wrench so the cam does NOT rotate when you remove the bolt)Leave the intake sprocket ON.
4. NOW slowly rotate the engine 1/4 turn up to TDC (spline at 12 o'clock) and install the crank sprocket. At this point the PIP mark on the chain drive should be at approx 5 o'clock. Then drop the chain down from above from the intake side making sure you are on the correct sides of the 2 "bosses" in the block.
*NOTE* DO NOT ROTATE THE CAMS WHEN AT TDC OR THE VALVES WILL HIT THE PISTONS AND BE DAMAGED!
5. Install the chain over the intake gear aligning the "odd" uniquely colored link to the PIP (should still be at 2 o'clock) The "odd" uniquely colored link is colored differently from the other 2 colored links on the chain (there are actually various different colors used depending on year) Work the chain down and around the crank gear ("even" colored mark should align) Drop the tensioner shoe down from above and install the pivot bolt (89 lb in)
6. Work the chain up towards the exhaust cam. A coat hanger works good here to pull the chain up through the head on the exhaust side and support it while you install the movable tensioning shoe. Then after insuring the other to links are still in alignment slip the chain around the exhaust sprocket (aligning the other "even" colored link to the EXH PIP mark) and align the exhaust gear with the cam and install the bolt (Again hand tight only) You MAY NEED to use a 24mm open end wrench to "slightly" rotate the cam against a loaded valve spring so that the sprocket properly aligns and will slip on and fully seat against the cam.
DO NOT INSTALL THE BOLT IN ORDER TO "SUCK" THE SPROCKET ONTO THE CAM OR DAMAGE WILL OCCUR!
7. After confirming once more that the PIP marks are all still aligned, install the RH "fixed" chain guide and tighten these bolts (one through the access hole in the head) to 11 lb ft. Put some thread sealer on the plastic plug and install into the head.
8. Install the upper guide on top of the head between the two sprockets (89 lb in)
9. Separate the halves of the tensioner mechanism and "collapse" the spring loaded mechanism by using a large screwdriver to turn it clockwise in order to "lock" it into a loaded state. (GM has a special tool for this of course) Reassemble the tensioner halves and MEASURE it's entire length. It SHOULD be 2.85" (72mm) or less if you successfully loaded the tensioner.
DO NOT INSTALL A RELEASED CHAIN TENSIONER (GREATER THAN 72MM) INTO THE BORE OR DAMAGE WILL OCCUR.
*Hint if you cant get the tensioner to "latch" into the loaded position PURCHASE A NEW TENSIONER as they come "preloaded"
10. Lubricate the tensioner seal with a bit of engine oil and install into the bore. tighten to 55 lb ft.
11. Next use a wooden dowl (aka broom handle
) or the handle end of a long screw driver, to come down from above and push sharply (bump hard with the palm of you hand) on the curved side of the tensioner shoe (collapsing the tensioner somewhat against the spring) in order to "release" the spring loaded mechanism within the tensioner. You will know if you were successful as the chain will get noticeably tighter.12. Once again reconfirm the engine is at TDC and that all the PIP marks are STILL in alignment. Then use a 24 mm wrench to hold each cam while you tighten the NEW sprocket mount bolts to 63 lb ft THEN use a torque angle meter/gage to apply an additional 30 degrees of tightness on the bolts.
These are torque-to-yield fasteners so this accuracy is important! DO NOT reuse these bolts as they will NOT be able to hold the sprockets tight enough once they have been torqued even ONCE to their yeild (stretch) point.
*You can now reassemble the front cover and rest of the assembly. On an LSJ now is a good time to install the CAM POSITION SENSOR (aligning the PIP marks on th drive hex and the housing) as it gets timed to TDC as well.
Last edited by WopOnTour; Sep 17, 2007 at 02:57 PM.
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Joined: 01-22-06
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From: Canada
Got her finished, fired up on the first try. Thanks for everyones help, its been a long process. Feels good to have her back again
I threw code P0015, can't find it in either 2005 or 2006 lists. Anyone know what it is, is it the case relearn code?
I threw code P0015, can't find it in either 2005 or 2006 lists. Anyone know what it is, is it the case relearn code?
Last edited by JMAc88; Sep 17, 2007 at 03:01 PM. Reason: Automerged Doublepost
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From: Pittsburgh, PA
Haha, when we timed Witts motor for the 2nd time, we re-used the stretch bolts with some loctite.
When we did mine for about the 9th time, we just stuck the tensionor in with it being already sprung.
Specs are overrated.
When we did mine for about the 9th time, we just stuck the tensionor in with it being already sprung.
Specs are overrated.
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From: Chester, VA
I don't see it in this list....can you check the code again......
and who ever told me to "go to hell" w/neg rep thanks
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Joined: 07-04-05
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From: No where man
FYI Locktite can't "add" sufficent clamp load it can only keep the threads from loosening, but even if you tightened it to spec, the clamp load is still far too low (already pushed past yield) and the fastener "could" fail at any time.
But I guess it might not be worth it for $15
Do what ever you want, but IMO- Specs Rule!
Wop
Any chance it's been triggered? Who'd ya hit!?
Wop
Last edited by WopOnTour; Sep 17, 2007 at 03:53 PM. Reason: Automerged Doublepost
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From: Pittsburgh, PA
Oh i Agree it's stupid, but my motor will be coming apart again because I am not finished with it. For now it will do.
BTW WoP, while you are on here... Does exactly does the Camshaft Position Sensor on the Exhaust camshaft do? I know it allowed the car to be turned over on first crank, but other than that? Just curious on what my car is missing out on. It is physically connected, just not electronically.
BTW WoP, while you are on here... Does exactly does the Camshaft Position Sensor on the Exhaust camshaft do? I know it allowed the car to be turned over on first crank, but other than that? Just curious on what my car is missing out on. It is physically connected, just not electronically.
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From: Canada
No such DTC. At least on the Cobalt. (generically P0015 is realated to certain aspects of VVT performance) Are you sure it's not B0015? Which is the drivers side seat belt pretensioner circuit (part of the seat belt retractor). Check the yellow connector for the pretensioner, IIRC it's under the drivers seat.
Any chance it's been triggered? Who'd ya hit!?
Wop
Any chance it's been triggered? Who'd ya hit!?
Wop
Also, the car sounds good, but has a slightly different idle then i remember. Will a relearn get rid of that or is it normal?
thanks
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From: Canada
ok, the code has changed to
P0017 Crankshaft Position (CKP) - Exhaust Camshaft Position (CMP) Correlation - ECM, PCM
under normal and hard acceleration the car sounds great, but if i go wot, there is a wierd clicking noise that comes from somewhere in the car. It is fairly loud, some people are saying the timing chain tensioner isn't taking up enough slack and is causing the chain to slap.
Any input?
P0017 Crankshaft Position (CKP) - Exhaust Camshaft Position (CMP) Correlation - ECM, PCM
under normal and hard acceleration the car sounds great, but if i go wot, there is a wierd clicking noise that comes from somewhere in the car. It is fairly loud, some people are saying the timing chain tensioner isn't taking up enough slack and is causing the chain to slap.
Any input?
yah like i said i think its possibly your timing chain, but i have to hear it, could eb something exhaust related, i dont belive itd be piston against valve noice as itd be all the time and the car would run like hell
also once u get your CASE relearn you p0017 will dissapear
also once u get your CASE relearn you p0017 will dissapear
Last edited by sunfirejoe; Sep 18, 2007 at 10:51 PM. Reason: Automerged Doublepost
Thread Starter
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Joined: 01-22-06
Posts: 537
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From: Canada
yah like i said i think its possibly your timing chain, but i have to hear it, could eb something exhaust related, i dont belive itd be piston against valve noice as itd be all the time and the car would run like hell
also once u get your CASE relearn you p0017 will dissapear
also once u get your CASE relearn you p0017 will dissapear
Lol, i know its probably something simple, but you know me, i am one paranoid **** when it comes to my car
Well the marks WILL NOT align after 2 rotations, (like a SBC for instance) Due to the chain to gear ratios involved IIRC it will take something like 44 revolutions to realign the links/marks!
The basic cam, timing chain and sprocket installation sequence goes something like this:
1. Start by making sure the engine is at a "safe" position with all pistons "down bore" The ideal spot is 90 degrees before TDC when ALL piston will be 1/2 way down bore. Use the spline on the crank snout as a guide. When this spline is at 12 o'clock you are at TDC on cylinder 1 and 4. So by placing the spline at 9 o'clock it will be 90 degrees BTDC. This insures that the valves absolutely CANNOT hit the pistons. The cams should still be removed when you do this so nothing will be damaged. If you turn the engine with the chain removed and the cam/s installed, you risk bending a valve as the Ecotecs are ALL "interference" design. *Hint* The engine will be much easier to turn if the spark plugs are removed. GM has a special socket that fits into the spline for turning the engine at the crank snout, but it's jsut as easy to reinstall the crank pulley bolt.
2. With the engine at this safe position and all the lash adjusters and roller followers in place install the cams (least loaded position) install all the cam caps in their original locations (they are marked) then torque all the cam caps gradally and evenly to 89 lb in (small head) and 18 lb ft (large head). You will need to apply some sealer to the large cap at the end of the cam (which cam depends on which Ecotec engine)to prevent an oil leak.
MAKE SURE ALL OF THE ROLLER FOLLOWERS HAVE STAYED PROPERLY PERCHED ON THE VALVE- THEY TEND TO FALL OFF WHILE TORQUING!.
Next install the sprockets onto the cams. Hand tighten the bolts at this time only as they are torque-to-yield type. (These must be NEW bolts as the MUST NOT be reused or they WILL come loose= disaster! ) Hand tighten means using a wrench or socket so the items are tight enough that they wont move, don't mistake this for "finger" tight (which I've seen happen here as a common error that screws things up later)
3. Confirm the engine is STILL in the "safe" position, then use a large open end wrench (24mm) to rotate the cams (using the hex flats between the lobes) until the the cam gear PIP (Part In Position) marks are at 10 o'clock (exhaust= triangle shaped) and 2 o'clock (intake= diamond shaped) Then remove the exhaust sprocket.(Hold the cam with the wrench so the cam does NOT rotate when you remove the bolt)Leave the intake sprocket ON.
4. NOW slowly rotate the engine 1/4 turn up to TDC (spline at 12 o'clock) and install the crank sprocket. At this point the PIP mark on the chain drive should be at approx 5 o'clock. Then drop the chain down from above from the intake side making sure you are on the correct sides of the 2 "bosses" in the block.
*NOTE* DO NOT ROTATE THE CAMS WHEN AT TDC OR THE VALVES WILL HIT THE PISTONS AND BE DAMAGED!
5. Install the chain over the intake gear aligning the "odd" uniquely colored link to the PIP (should still be at 2 o'clock) The "odd" uniquely colored link is colored differently from the other 2 colored links on the chain (there are actually various different colors used depending on year) Work the chain down and around the crank gear ("even" colored mark should align) Drop the tensioner shoe down from above and install the pivot bolt (89 lb in)
6. Work the chain up towards the exhaust cam. A coat hanger works good here to pull the chain up through the head on the exhaust side and support it while you install the movable tensioning shoe. Then after insuring the other to links are still in alignment slip the chain around the exhaust sprocket (aligning the other "even" colored link to the EXH PIP mark) and align the exhaust gear with the cam and install the bolt (Again hand tight only) You MAY NEED to use a 24mm open end wrench to "slightly" rotate the cam against a loaded valve spring so that the sprocket properly aligns and will slip on and fully seat against the cam.
DO NOT INSTALL THE BOLT IN ORDER TO "SUCK" THE SPROCKET ONTO THE CAM OR DAMAGE WILL OCCUR!
7. After confirming once more that the PIP marks are all still aligned, install the RH "fixed" chain guide and tighten these bolts (one through the access hole in the head) to 11 lb ft. Put some thread sealer on the plastic plug and install into the head.
8. Install the upper guide on top of the head between the two sprockets (89 lb in)
9. Separate the halves of the tensioner mechanism and "collapse" the spring loaded mechanism by using a large screwdriver to turn it clockwise in order to "lock" it into a loaded state. (GM has a special tool for this of course) Reassemble the tensioner halves and MEASURE it's entire length. It SHOULD be 2.85" (72mm) or less if you successfully loaded the tensioner.
DO NOT INSTALL A RELEASED CHAIN TENSIONER (GREATER THAN 72MM) INTO THE BORE OR DAMAGE WILL OCCUR.
*Hint if you cant get the tensioner to "latch" into the loaded position PURCHASE A NEW TENSIONER as they come "preloaded"
10. Lubricate the tensioner seal with a bit of engine oil and install into the bore. tighten to 55 lb ft.
11. Next use a wooden dowl (aka broom handle) or the handle end of a long screw driver, to come down from above and push sharply (bump hard with the palm of you hand) on the curved side of the tensioner shoe (collapsing the tensioner somewhat against the spring) in order to "release" the spring loaded mechanism within the tensioner. You will know if you were successful as the chain will get noticeably tighter.
12. Once again reconfirm the engine is at TDC and that all the PIP marks are STILL in alignment. Then use a 24 mm wrench to hold each cam while you tighten the NEW sprocket mount bolts to 63 lb ft THEN use a torque angle meter/gage to apply an additional 30 degrees of tightness on the bolts.
These are torque-to-yield fasteners so this accuracy is important! DO NOT reuse these bolts as they will NOT be able to hold the sprockets tight enough once they have been torqued even ONCE to their yeild (stretch) point.
*You can now reassemble the front cover and rest of the assembly. On an LSJ now is a good time to install the CAM POSITION SENSOR (aligning the PIP marks on th drive hex and the housing) as it gets timed to TDC as well.
The basic cam, timing chain and sprocket installation sequence goes something like this:
1. Start by making sure the engine is at a "safe" position with all pistons "down bore" The ideal spot is 90 degrees before TDC when ALL piston will be 1/2 way down bore. Use the spline on the crank snout as a guide. When this spline is at 12 o'clock you are at TDC on cylinder 1 and 4. So by placing the spline at 9 o'clock it will be 90 degrees BTDC. This insures that the valves absolutely CANNOT hit the pistons. The cams should still be removed when you do this so nothing will be damaged. If you turn the engine with the chain removed and the cam/s installed, you risk bending a valve as the Ecotecs are ALL "interference" design. *Hint* The engine will be much easier to turn if the spark plugs are removed. GM has a special socket that fits into the spline for turning the engine at the crank snout, but it's jsut as easy to reinstall the crank pulley bolt.
2. With the engine at this safe position and all the lash adjusters and roller followers in place install the cams (least loaded position) install all the cam caps in their original locations (they are marked) then torque all the cam caps gradally and evenly to 89 lb in (small head) and 18 lb ft (large head). You will need to apply some sealer to the large cap at the end of the cam (which cam depends on which Ecotec engine)to prevent an oil leak.
MAKE SURE ALL OF THE ROLLER FOLLOWERS HAVE STAYED PROPERLY PERCHED ON THE VALVE- THEY TEND TO FALL OFF WHILE TORQUING!.
Next install the sprockets onto the cams. Hand tighten the bolts at this time only as they are torque-to-yield type. (These must be NEW bolts as the MUST NOT be reused or they WILL come loose= disaster! ) Hand tighten means using a wrench or socket so the items are tight enough that they wont move, don't mistake this for "finger" tight (which I've seen happen here as a common error that screws things up later)
3. Confirm the engine is STILL in the "safe" position, then use a large open end wrench (24mm) to rotate the cams (using the hex flats between the lobes) until the the cam gear PIP (Part In Position) marks are at 10 o'clock (exhaust= triangle shaped) and 2 o'clock (intake= diamond shaped) Then remove the exhaust sprocket.(Hold the cam with the wrench so the cam does NOT rotate when you remove the bolt)Leave the intake sprocket ON.
4. NOW slowly rotate the engine 1/4 turn up to TDC (spline at 12 o'clock) and install the crank sprocket. At this point the PIP mark on the chain drive should be at approx 5 o'clock. Then drop the chain down from above from the intake side making sure you are on the correct sides of the 2 "bosses" in the block.
*NOTE* DO NOT ROTATE THE CAMS WHEN AT TDC OR THE VALVES WILL HIT THE PISTONS AND BE DAMAGED!
5. Install the chain over the intake gear aligning the "odd" uniquely colored link to the PIP (should still be at 2 o'clock) The "odd" uniquely colored link is colored differently from the other 2 colored links on the chain (there are actually various different colors used depending on year) Work the chain down and around the crank gear ("even" colored mark should align) Drop the tensioner shoe down from above and install the pivot bolt (89 lb in)
6. Work the chain up towards the exhaust cam. A coat hanger works good here to pull the chain up through the head on the exhaust side and support it while you install the movable tensioning shoe. Then after insuring the other to links are still in alignment slip the chain around the exhaust sprocket (aligning the other "even" colored link to the EXH PIP mark) and align the exhaust gear with the cam and install the bolt (Again hand tight only) You MAY NEED to use a 24mm open end wrench to "slightly" rotate the cam against a loaded valve spring so that the sprocket properly aligns and will slip on and fully seat against the cam.
DO NOT INSTALL THE BOLT IN ORDER TO "SUCK" THE SPROCKET ONTO THE CAM OR DAMAGE WILL OCCUR!
7. After confirming once more that the PIP marks are all still aligned, install the RH "fixed" chain guide and tighten these bolts (one through the access hole in the head) to 11 lb ft. Put some thread sealer on the plastic plug and install into the head.
8. Install the upper guide on top of the head between the two sprockets (89 lb in)
9. Separate the halves of the tensioner mechanism and "collapse" the spring loaded mechanism by using a large screwdriver to turn it clockwise in order to "lock" it into a loaded state. (GM has a special tool for this of course) Reassemble the tensioner halves and MEASURE it's entire length. It SHOULD be 2.85" (72mm) or less if you successfully loaded the tensioner.
DO NOT INSTALL A RELEASED CHAIN TENSIONER (GREATER THAN 72MM) INTO THE BORE OR DAMAGE WILL OCCUR.
*Hint if you cant get the tensioner to "latch" into the loaded position PURCHASE A NEW TENSIONER as they come "preloaded"
10. Lubricate the tensioner seal with a bit of engine oil and install into the bore. tighten to 55 lb ft.
11. Next use a wooden dowl (aka broom handle
) or the handle end of a long screw driver, to come down from above and push sharply (bump hard with the palm of you hand) on the curved side of the tensioner shoe (collapsing the tensioner somewhat against the spring) in order to "release" the spring loaded mechanism within the tensioner. You will know if you were successful as the chain will get noticeably tighter.12. Once again reconfirm the engine is at TDC and that all the PIP marks are STILL in alignment. Then use a 24 mm wrench to hold each cam while you tighten the NEW sprocket mount bolts to 63 lb ft THEN use a torque angle meter/gage to apply an additional 30 degrees of tightness on the bolts.
These are torque-to-yield fasteners so this accuracy is important! DO NOT reuse these bolts as they will NOT be able to hold the sprockets tight enough once they have been torqued even ONCE to their yeild (stretch) point.
*You can now reassemble the front cover and rest of the assembly. On an LSJ now is a good time to install the CAM POSITION SENSOR (aligning the PIP marks on th drive hex and the housing) as it gets timed to TDC as well.
agreed great write up... but i did it a way that seemed to be quite a bit easier... i did what you said but set everything up while it was 90* before top dead center as it was easier on the top side i only had to tension the intake valve springs a tad and the gear slipped right on, turned everything to top dead center checked alignment of marks and released tensioner checked marks again and was good to go...
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