Valve spring replacement on C7 Z
Sr.Random input generator
Joined: Jan 2008
Posts: 7,803
Likes: 2,232
From: Sammamish, WA
I'm planning to do this on my '19 C7 Z06. It's still at less thank 10K miles, but I to go to track a lot, and I think after 2 years, this might be nice. Does the list below make sense? Would you need to change anything else? Any other gasket, etc.?
What do you guys think? My local race shops is asking $1K for labor, and I'm hoping I can do this myself, but would love to check with those who've done it before. I'm an engine internals noob, and your input is appreciated : )
Also, besides these, I also ordered OEM spark plugs and plug wire set. Since I'd need to remove them one by one to pressurize the cylinders, I thought I might as well replace them with new ones.
- 16x valve springs: 12691120
- 8x exhaust valve seal: 12689006
- 8x intake valve seal: 12689007
- Compressor tool (link)
- Valve holder ( )
What do you guys think? My local race shops is asking $1K for labor, and I'm hoping I can do this myself, but would love to check with those who've done it before. I'm an engine internals noob, and your input is appreciated : )
Also, besides these, I also ordered OEM spark plugs and plug wire set. Since I'd need to remove them one by one to pressurize the cylinders, I thought I might as well replace them with new ones.
Last edited by X25; Sep 24, 2020 at 05:52 AM.
Racer
Joined: Mar 2016
Posts: 399
Likes: 31
From: Columbus Ohio
I'm planning to do this on my '19 C7 Z06. It's still at less thank 10K miles, but I to go to track a lot, and I think after 2 years, this might be nice. Does the list below make sense? Would you need to change anything else? Any other gasket, etc.?
What do you guys think? My local race shops is asking $1K for labor, and I'm hoping I can do this myself, but would love to check with those who've done it before. I'm an engine internals noob, and your input is appreciated : )
Also, besides these, I also ordered OEM spark plugs and plug wire set. Since I'd need to remove them one by one to pressurize the cylinders, I thought I might as well replace them with new ones.
- 16x valve springs: 12691120
- 8x exhaust valve seal: 12689006
- 8x intake valve seal: 12689007
- Compressor tool (link)
- Valve holder (link)
What do you guys think? My local race shops is asking $1K for labor, and I'm hoping I can do this myself, but would love to check with those who've done it before. I'm an engine internals noob, and your input is appreciated : )
Also, besides these, I also ordered OEM spark plugs and plug wire set. Since I'd need to remove them one by one to pressurize the cylinders, I thought I might as well replace them with new ones.
Sr.Random input generator
Joined: Jan 2008
Posts: 7,803
Likes: 2,232
From: Sammamish, WA
These are all OEM parts. I'm pretty dim on engine internal upgrades since I never touch it. Could you please elaborate on why it's important to upgrade those rocker arms, and how I can do it (is there an aftermarket part?) Are OEM rocker arms known to fail?
Racer
Joined: Mar 2016
Posts: 399
Likes: 31
From: Columbus Ohio
Old parts are in the container on the right. You can do it with a bench vise or press, and comp sells a tool that makes life super easy. I think its around 350-400 for the tool and bushings.
Instructor
Joined: Sep 2019
Posts: 111
Likes: 21
From: Weeki Wachee, FL
@FYREANT Sorry to revive an old thread, figured keep it all in one spot. I'm getting ready to replace my valve springs with BTR Valve Kit and the Trunion upgrade as well. I have the spring compressor tool, the air compressor tool and a shop press. Anything special I need to know when doing the trunion upgrade and I'm assuming you have to spin the crank to get the valves in the closed seated position before removing tension of the rocker arms?
I'm Batman..
Joined: Apr 2014
Posts: 6,142
Likes: 921
From: Lehigh Acres FL
Tech Contributor
@FYREANT Sorry to revive an old thread, figured keep it all in one spot. I'm getting ready to replace my valve springs with BTR Valve Kit and the Trunion upgrade as well. I have the spring compressor tool, the air compressor tool and a shop press. Anything special I need to know when doing the trunion upgrade and I'm assuming you have to spin the crank to get the valves in the closed seated position before removing tension of the rocker arms?
Instructor
Joined: Sep 2019
Posts: 111
Likes: 21
From: Weeki Wachee, FL
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Instructor
Joined: Sep 2019
Posts: 111
Likes: 21
From: Weeki Wachee, FL
Ant.. please forgive me in advance for asking a stupid question. I found your How-To, but if I'm doing this with the engine still in the car, do I just find TDC on Cylinder #1 and it's just the same as below? Or is there another way to do it? Also, when removing the rocker arms I just want to clarify that all I need to do is rotate the crank so that the valves are in the closed position before removing them, and it's no specific order.. just as long as the valves are closed? In other words, I should be able to take of Cylinder #1, 5, 2, 6 for example only.
1. Ensure that the engine is at top dead center of the compression stroke. (if you have not rotated the crankshaft, then you are still at TDC at this point, "dot-to-dot"). In this position, Cylinder 1 will be "off-lobe" on base of circle, and the crankshaft sprocket key will be at the 1:30 position.
2. The engine firing order is 1, 8, 7, 2, 6, 5, 4, 3
Cylinders 1, 3, 5, 7 are left bank
Cylinders 2, 4, 6, 8 are right bank
3. Tighten the rocker arm bolts for the EXHAUST VALVES for 1, 2, 7, and 8 to 22 lb. ft.
4. Tighten the rocker arm bolts for the INTAKE VALVES for 1, 3, 4, and 5 to 22 lb. ft.
5. Rotate the crankshaft 360 degrees.
6. Tighten the rocker arm bolts for the EXHAUST VALVES for 3, 4, 5, and 6 to 22 lb. ft.
7. Tighten the rocker arm bolts for the INTAKE VALVES for 2, 6, 7, and 8 to 22 lb. ft.
Check, check, and check again to ensure you didn't miss any!!
I'm Batman..
Joined: Apr 2014
Posts: 6,142
Likes: 921
From: Lehigh Acres FL
Tech Contributor
Ant.. please forgive me in advance for asking a stupid question. I found your How-To, but if I'm doing this with the engine still in the car, do I just find TDC on Cylinder #1 and it's just the same as below? Or is there another way to do it? Also, when removing the rocker arms I just want to clarify that all I need to do is rotate the crank so that the valves are in the closed position before removing them, and it's no specific order.. just as long as the valves are closed? In other words, I should be able to take of Cylinder #1, 5, 2, 6 for example only.
1. Ensure that the engine is at top dead center of the compression stroke. (if you have not rotated the crankshaft, then you are still at TDC at this point, "dot-to-dot"). In this position, Cylinder 1 will be "off-lobe" on base of circle, and the crankshaft sprocket key will be at the 1:30 position.
2. The engine firing order is 1, 8, 7, 2, 6, 5, 4, 3
Cylinders 1, 3, 5, 7 are left bank
Cylinders 2, 4, 6, 8 are right bank
3. Tighten the rocker arm bolts for the EXHAUST VALVES for 1, 2, 7, and 8 to 22 lb. ft.
4. Tighten the rocker arm bolts for the INTAKE VALVES for 1, 3, 4, and 5 to 22 lb. ft.
5. Rotate the crankshaft 360 degrees.
6. Tighten the rocker arm bolts for the EXHAUST VALVES for 3, 4, 5, and 6 to 22 lb. ft.
7. Tighten the rocker arm bolts for the INTAKE VALVES for 2, 6, 7, and 8 to 22 lb. ft.
Check, check, and check again to ensure you didn't miss any!!
1. Ensure that the engine is at top dead center of the compression stroke. (if you have not rotated the crankshaft, then you are still at TDC at this point, "dot-to-dot"). In this position, Cylinder 1 will be "off-lobe" on base of circle, and the crankshaft sprocket key will be at the 1:30 position.
2. The engine firing order is 1, 8, 7, 2, 6, 5, 4, 3
Cylinders 1, 3, 5, 7 are left bank
Cylinders 2, 4, 6, 8 are right bank
3. Tighten the rocker arm bolts for the EXHAUST VALVES for 1, 2, 7, and 8 to 22 lb. ft.
4. Tighten the rocker arm bolts for the INTAKE VALVES for 1, 3, 4, and 5 to 22 lb. ft.
5. Rotate the crankshaft 360 degrees.
6. Tighten the rocker arm bolts for the EXHAUST VALVES for 3, 4, 5, and 6 to 22 lb. ft.
7. Tighten the rocker arm bolts for the INTAKE VALVES for 2, 6, 7, and 8 to 22 lb. ft.
Check, check, and check again to ensure you didn't miss any!!
Instructor
Joined: Sep 2019
Posts: 111
Likes: 21
From: Weeki Wachee, FL
Thanks Ant. Ok right.. so when taking the rockers off rotate the crank so that valves are closed realizing that I can’t take both rockers off on any one cylinder because one is intake and other is exhaust.
When reinstalling, how do I get to the “dot-to-dot” without being able to see the crank? Is TDC on Cylinder #1 the same? What steps do I take in order to get to be able to follow your torque procedures outlined above?
When reinstalling, how do I get to the “dot-to-dot” without being able to see the crank? Is TDC on Cylinder #1 the same? What steps do I take in order to get to be able to follow your torque procedures outlined above?
I'm Batman..
Joined: Apr 2014
Posts: 6,142
Likes: 921
From: Lehigh Acres FL
Tech Contributor
Thanks Ant. Ok right.. so when taking the rockers off rotate the crank so that valves are closed realizing that I can’t take both rockers off on any one cylinder because one is intake and other is exhaust.
When reinstalling, how do I get to the “dot-to-dot” without being able to see the crank? Is TDC on Cylinder #1 the same? What steps do I take in order to get to be able to follow your torque procedures outlined above?
When reinstalling, how do I get to the “dot-to-dot” without being able to see the crank? Is TDC on Cylinder #1 the same? What steps do I take in order to get to be able to follow your torque procedures outlined above?
Instructor
Joined: Sep 2019
Posts: 111
Likes: 21
From: Weeki Wachee, FL
Ok so just so I'm clear.. (it's not you, it's me! LOL). There is no doubt that I am overthinking this, but I'd rather do it once now and be comfortable enough to do it every 15-20k miles in the future. Here's what I've learned so far.. please let me know when you get a chance before I dig into it:
Sorry to be beating this horse to death.. just want to make sure I got it down. Again, thanks for all the help!
- I can take the rockers off in any order, just need to only make sure that the valves have no pressure on them, and is in the closed position by rotating the crank
- Once rockers are all off, lightly tap retainers with rubber mallet (not valve stem) to break keepers seal around stem. (No need to remove pushrods unless valve spring compressor gets in the way right?)
- Install pneumatic air fitting into cylinder to be worked on.
- Rotate crank to compression stroke so that both valves are in the closed position (Is this correct, I assume this because the air won't seal the chamber?)
- Apply constant air pressure (90psi) to cylinder. You will hear slight leaking past the rings.
- Remove retainers, valve springs, keepers, and valve seals. Replace - Reinstall.
- Move to next Cylinder and repeat steps 3-6.
- Once all cylinders have been completed, install all rocker arms loosely by hand and verify correct seating by spinning the valve stem.
- Rotate crank to TDC on cylinder #1. Use sharpie or something else to mark where TDC was on crank pulley and body of engine somehow.
- Tighten the rocker arm bolts for the EXHAUST VALVES for 1, 2, 7, and 8 to 22 lb. ft.
- Tighten the rocker arm bolts for the INTAKE VALVES for 1, 3, 4, and 5 to 22 lb. ft.
- Rotate the crankshaft 360 degrees using sharpie mark for reference.
- Tighten the rocker arm bolts for the EXHAUST VALVES for 3, 4, 5, and 6 to 22 lb. ft.
- Tighten the rocker arm bolts for the INTAKE VALVES for 2, 6, 7, and 8 to 22 lb. ft.
- Check, check, and check again to ensure you didn't miss any!!
Sorry to be beating this horse to death.. just want to make sure I got it down. Again, thanks for all the help!
Last edited by SteenC7Z; Dec 29, 2020 at 08:58 PM.
I'm Batman..
Joined: Apr 2014
Posts: 6,142
Likes: 921
From: Lehigh Acres FL
Tech Contributor
Ok so just so I'm clear.. (it's not you, it's me! LOL). There is no doubt that I am overthinking this, but I'd rather do it once now and be comfortable enough to do it every 15-20k miles in the future. Here's what I've learned so far.. please let me know when you get a chance before I dig into it:
Sorry to be beating this horse to death.. just want to make sure I got it down. Again, thanks for all the help!
- I can take the rockers off in any order, just need to only make sure that the valves have no pressure on them, and is in the closed position by rotating the crank
- Once rockers are all off, lightly tap retainers with rubber mallet (not valve stem) to break keepers seal around stem. (No need to remove pushrods unless valve spring compressor gets in the way right?)
- Install pneumatic air fitting into cylinder to be worked on.
- Rotate crank to compression stroke so that both valves are in the closed position (Is this correct, I assume this because the air won't seal the chamber?)
- Apply constant air pressure (90psi) to cylinder. You will hear slight leaking past the rings.
- Remove retainers, valve springs, keepers, and valve seals. Replace - Reinstall.
- Move to next Cylinder and repeat steps 3-6.
- Once all cylinders have been completed, install all rocker arms loosely by hand and verify correct seating by spinning the valve stem.
- Rotate crank to TDC on cylinder #1. Use sharpie or something else to mark where TDC was on crank pulley and body of engine somehow.
- Tighten the rocker arm bolts for the EXHAUST VALVES for 1, 2, 7, and 8 to 22 lb. ft.
- Tighten the rocker arm bolts for the INTAKE VALVES for 1, 3, 4, and 5 to 22 lb. ft.
- Rotate the crankshaft 360 degrees using sharpie mark for reference.
- Tighten the rocker arm bolts for the EXHAUST VALVES for 3, 4, 5, and 6 to 22 lb. ft.
- Tighten the rocker arm bolts for the INTAKE VALVES for 2, 6, 7, and 8 to 22 lb. ft.
- Check, check, and check again to ensure you didn't miss any!!
Sorry to be beating this horse to death.. just want to make sure I got it down. Again, thanks for all the help!
- I can take the rockers off in any order, just need to only make sure that the valves have no pressure on them, and is in the closed position by rotating the crank
Correct, however, a couple notes: First, it is recommended to perform step 9 and remove them while they are off lobe to prevent damage to the rocker pedestal. Also, I would personally do them one at a time and in a specific order to make sure nothing gets missed. Like, do Intake valves 1-8 then exhaust 1-8. That is up to you though, I'm just particular. Mark you crank now when you find TDC. Every TWO complete revolutions (720 degrees) of the crank will bring you back to the same exact spot. Only 1 revolution (360 degrees) brings you back to TDC but one is the compression stroke and the next is the combustion stroke. - Once rockers are all off, lightly tap retainers with rubber mallet (not valve stem) to break keepers seal around stem. (No need to remove pushrods unless valve spring compressor gets in the way right?)
Correct. - Install pneumatic air fitting into cylinder to be worked on.
Correct. - Rotate crank to compression stroke so that both valves are in the closed position (Is this correct, I assume this because the air won't seal the chamber?)
See below picture directly from the service manual. It will provide more detailed information about this step so you can keep track of where your crank needs to be during the process. - Apply constant air pressure (90psi) to cylinder. You will hear slight leaking past the rings.
Correct. - Remove retainers, valve springs, keepers, and valve seals. Replace - Reinstall.
Yes, but again, you'll only be able to do one of the valves at a time since likely the other valve will be slightly open. - Move to next Cylinder and repeat steps 3-6.
Correct. - Once all cylinders have been completed, install all rocker arms loosely by hand and verify correct seating by spinning the valve stem.
No, while installing them and getting them finger tight/snug, (finger tight meaning there is NO wiggle room of the rocker arm by hand) then you need to rotate the pushrod, not the valvestem. - Rotate crank to TDC on cylinder #1. Use sharpie or something else to mark where TDC was on crank pulley and body of engine somehow.
Yes, and this step is important to do in step 1 as I mentioned, and also critical to keep an accurate account of where it is through the whole process. - Tighten the rocker arm bolts for the EXHAUST VALVES for 1, 2, 7, and 8 to 22 lb. ft.
See below picture directly from the service manual. It will provide more detailed information about this step for you. - Tighten the rocker arm bolts for the INTAKE VALVES for 1, 3, 4, and 5 to 22 lb. ft.
See below picture directly from the service manual. It will provide more detailed information about this step for you - Rotate the crankshaft 360 degrees using sharpie mark for reference.
Yes, and double and triple check your torque specs of each of the rocker arms again, when off lobe!
Ant
Last edited by FYREANT; Dec 31, 2020 at 01:05 PM.