having trouble finding tdc for rocker install
10-19-2010, 01:21 PM
#1
TECH Fanatic
Thread Starter
iTrader: (2)
Join Date: Sep 2007
Location: Cairo, GA
Posts: 1,235
Likes: 0
Received 0 Likes
on
0 Posts
having trouble finding tdc for rocker install i took all my rockers off yesterday to check my pushrods because i suspected one or two may have been bent. none were bent so i put them back in and now i'm trying to properly torque my rockers back on. i know they need to be at 22 ft/lbs. but i'm having the hardest figuring out when cylinder 1 is at tdc on the compression stroke to start torquing them. i can't see down through the spark plug hole to see the piston and i can't feel it with a small screw driver. all my rockers are loose at the moment. any help would be greatly appreciated, i thought this was going to be an afternoon job, but for some reason i'm having issues. thanks! and this is the method i'm going by:
Install the rocker arms and bolts.
Rotate the crankshaft until number one piston is at top dead center of compression stroke. In this position, cylinder number one rocker arms will be off lobe lift, and the crankshaft sprocket key will be at the 1:30 position. If viewing from the rear of the engine, the additional crankshaft pilot hole, non-threaded, will be in the 10:30 position. The engine firing order is 1, 8, 7, 2, 6, 5, 4, 3. Cylinders 1, 3, 5 and 7 are left bank. Cylinders 2, 4, 6, and 8 are right bank.
Notice
Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.
With the engine in the number one firing position, tighten the following valve rocker arm bolts: Tighten
Tighten exhaust valve rocker arm bolts 1, 2, 7, and 8 to 30 N·m (22 lb ft).
Tighten intake valve rocker arm bolts 1, 3, 4, and 5 to 30 N·m (22 lb ft).
Rotate the crankshaft 360 degrees.
Tighten the following valve rocker arm bolts: Tighten
Tighten exhaust valve rocker arm bolts 3, 4, 5, and 6 to 30 N·m (22 lb ft).
Tighten intake valve rocker arm bolts 2, 6, 7, and 8 to 30 N·m (22 lb ft).
Install the rocker arms and bolts.
Rotate the crankshaft until number one piston is at top dead center of compression stroke. In this position, cylinder number one rocker arms will be off lobe lift, and the crankshaft sprocket key will be at the 1:30 position. If viewing from the rear of the engine, the additional crankshaft pilot hole, non-threaded, will be in the 10:30 position. The engine firing order is 1, 8, 7, 2, 6, 5, 4, 3. Cylinders 1, 3, 5 and 7 are left bank. Cylinders 2, 4, 6, and 8 are right bank.
Notice
Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.
With the engine in the number one firing position, tighten the following valve rocker arm bolts: Tighten
Tighten exhaust valve rocker arm bolts 1, 2, 7, and 8 to 30 N·m (22 lb ft).
Tighten intake valve rocker arm bolts 1, 3, 4, and 5 to 30 N·m (22 lb ft).
Rotate the crankshaft 360 degrees.
Tighten the following valve rocker arm bolts: Tighten
Tighten exhaust valve rocker arm bolts 3, 4, 5, and 6 to 30 N·m (22 lb ft).
Tighten intake valve rocker arm bolts 2, 6, 7, and 8 to 30 N·m (22 lb ft).
10-19-2010, 01:24 PM
#2
This is what I got and cop'd and paste it:
Look at cylinder #1 (driver's side forward set of rocker arms) and the intake valve, which is the left one.
Rotate the motor until the intake is seen to open then close.
Once it closes you have less than 1/2 of the crank to get the piston to the top.
Turn the crank another 1/4 turn and then either with a flashlight or a straw in the spark plug hole turn the crank until the #1 piston is at the top.
Once there, mark the pulley at 12 o'clock so you can then follow the GM procedure.
Install the rocker arms and bolts.
Rotate the crankshaft until number one piston is at top dead center of compression stroke.
In this position, cylinder number one rocker arms will be off lobe lift, and the crankshaft sprocket key will be at the 1:30 position.
If viewing from the rear of the engine, the additional crankshaft pilot hole, non-threaded, will be in the 10:30 position.
The engine firing order is 1, 8, 7, 2, 6, 5, 4, 3. Cylinders 1, 3, 5 and 7 are left bank.
Cylinders 2, 4, 6, and 8 are right bank.
Notice
Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.
With the engine in the number one firing position, tighten the following valve rocker arm bolts: Tighten
Tighten exhaust valve rocker arm bolts 1, 2, 7, and 8 to 30 N·m (22 lb ft).
Tighten intake valve rocker arm bolts 1, 3, 4, and 5 to 30 N·m (22 lb ft).
Rotate the crankshaft 360 degrees.
Tighten the following valve rocker arm bolts: Tighten
Tighten exhaust valve rocker arm bolts 3, 4, 5, and 6 to 30 N·m (22 lb ft).
Tighten intake valve rocker arm bolts 2, 6, 7, and 8 to 30 N·m (22 lb ft).
Look at cylinder #1 (driver's side forward set of rocker arms) and the intake valve, which is the left one.
Rotate the motor until the intake is seen to open then close.
Once it closes you have less than 1/2 of the crank to get the piston to the top.
Turn the crank another 1/4 turn and then either with a flashlight or a straw in the spark plug hole turn the crank until the #1 piston is at the top.
Once there, mark the pulley at 12 o'clock so you can then follow the GM procedure.
Install the rocker arms and bolts.
Rotate the crankshaft until number one piston is at top dead center of compression stroke.
In this position, cylinder number one rocker arms will be off lobe lift, and the crankshaft sprocket key will be at the 1:30 position.
If viewing from the rear of the engine, the additional crankshaft pilot hole, non-threaded, will be in the 10:30 position.
The engine firing order is 1, 8, 7, 2, 6, 5, 4, 3. Cylinders 1, 3, 5 and 7 are left bank.
Cylinders 2, 4, 6, and 8 are right bank.
Notice
Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.
With the engine in the number one firing position, tighten the following valve rocker arm bolts: Tighten
Tighten exhaust valve rocker arm bolts 1, 2, 7, and 8 to 30 N·m (22 lb ft).
Tighten intake valve rocker arm bolts 1, 3, 4, and 5 to 30 N·m (22 lb ft).
Rotate the crankshaft 360 degrees.
Tighten the following valve rocker arm bolts: Tighten
Tighten exhaust valve rocker arm bolts 3, 4, 5, and 6 to 30 N·m (22 lb ft).
Tighten intake valve rocker arm bolts 2, 6, 7, and 8 to 30 N·m (22 lb ft).
10-19-2010, 01:38 PM
#4
TECH Fanatic
Thread Starter
iTrader: (2)
Join Date: Sep 2007
Location: Cairo, GA
Posts: 1,235
Likes: 0
Received 0 Likes
on
0 Posts
this is probably a dumb question but just to clarify. my rockers are all loose right now so when i rotate the motor, it's harder to tell what the valves are doing. would there be any risk in tightening the rockers so that i can see them opening and closing as i'm rotating the crank? i would assume so, just want to make sure.
10-19-2010, 01:43 PM
#5
this is probably a dumb question but just to clarify. my rockers are all loose right now so when i rotate the motor, it's harder to tell what the valves are doing. would there be any risk in tightening the rockers so that i can see them opening and closing as i'm rotating the crank? i would assume so, just want to make sure.
10-19-2010, 02:08 PM
#7
Teching In
Join Date: Oct 2010
Posts: 19
Likes: 0
Received 0 Likes
on
0 Posts
Snug up the rockers to zero lash, rotate the crank if they loosen then snug them up, if they bind the springs then back them off to zero lash. Niether valve should be open at TDC, the rockers will be the same height.
Trending Topics
10-19-2010, 07:22 PM
#8
To the OP, if you watch the pushrod of the #1 intake go up (rocker can be off), continue to rotate and gently push down on the pushrod and you will feel it close and now piston is coming to top for TDC.
10-22-2010, 10:09 AM
#9
TECH Fanatic
Thread Starter
iTrader: (2)
Join Date: Sep 2007
Location: Cairo, GA
Posts: 1,235
Likes: 0
Received 0 Likes
on
0 Posts
well i turned to crank until the intake valve opened, then after it closed, used a screw driver to feel the piston come up and start to come back dow, then i bumped it back a little. now i'll torque half of them down, rotate the crank a full 360 degrees and torque the other half down, going by the GM procedure? thanks a lot guys, it was getting pretty frustrating 
