Lt1 rocker arm torque spec?
- Thread starter 95ltfun
- Start date
dave89iroc
Club Member
yeah, they are locking nut on an adjustable valvetrain
BIGCOWL-IMP
Club Member
Take the lash out then its 1 full turn.....
Adjusting Valves and Zero Lash
Zero lash is when you go from having slack between the lifter, pushrod and rocker arm, to the exact point of no slack. The lifter needs to be on the base of the lobe when setting valve lash. When a cylinder is at TDC, both lifters should be at the bottom of their travel (base of the cam lobe).
Gauging zero lash by hand is not an exact science. When setting the valve lash with the engine not running, you can get close enough by doing the "spin the pushrod" method. Loosen the rocker arm until you can feel slack in the pushrod to rocker arm. Spin the pushrod with your fingers while tighening the rocker arm back down. When you BEGIN to feel drag while spinning the pushrod, you are at zero lash. If you don't like the spin method, use the up/down slack method of gauging when the slack is gone. Once zero lash is reached, stop and add your preload. DO NOT go back and try to feel the adjustment again. The lifter will immediately begin to bleed down a little. Tension on the pushrod will relax and this will make it seem like your adjustment did not work. If you want to recheck zero lash, you must loosen the rocker arm nut and tighten it down again while manipulating the pushrod as before. At that point you want to set the preload and LEAVE IT ALONE.
The hydraulic lifter has an internal plunger that has a specific amount of travel. On stock engines, the purpose of preload is to compress the plunger so the pushrod will be riding on a "cushion" (acts like a shock absorber). With stock lifters, turning the rocker nut another ½ to ¾ turn, will normally put you in the ballpark for quiet operation without being too tight and the adjustment should last a long time. Most books show stock preload at up to 1 turn. Specific lifters like the Comp Cams "Comp R's", have less internal travel. ¼ turn preload is more than plenty, with 1/8 or just barely any preload being better for high revving engines. Comp actually recommends .002-.004 preload on a warm engine.
For reference:
3/8" stud: ½ flat = .003472"
7/16" stud: ½ flat = .00416"
Rotating the nut 1/6 of a turn (until the next flat side is in the same position as the previous flat side) is a "flat".
Consequences of improper adjustment:
Too tight - the valves will not completely close and you will lose compression. The engine will run rough, if it will run at all.
Too loose - the rocker arms will make noise from the slack and pushrods could be dislodged. Possible damage could occur from either extreme.
Engine Running Method
Some like to adjust the rockers while the car is idling. If you wish to do this, loosen one rocker at a time until you can hear it click. Tighten the nut, but don't exert downward pressure on the rocker arm with your socket or wrench. At the point when audible clicking is gone, tighten the nut another 1/4 turn (or whatever desired) for your preload (Comp R lifters, less as noted above).
Engine Not Running Methods
There are several methods for setting the lash with the engine not running and are listed below. Read through them all. You might prefer one method over another. They all accomplish the same thing.
Method 1
If you have never had the crank hub off (or know for sure that it's orientation is correct), you can use the arrow that is on the balancer to tell you where you are. You don't have to spin the crank every 90º with this method.
When the arrow is at 12 o'clock you will be at either #1 or #6 TDC. You might have trouble identifying whether #1 or #6 is at TDC when the crank arrow is at 12 o'clock. Probably the easiest way is to look over the other valves or lifter positions. Compare them to the charts below, showing which can be adjusted. Any valve that can be adjusted should be UP (closed) and the lifter/pushrod should be down. Valves that are not to be adjusted will be in varying d ees of being open or DOWN (lifters/pushrods UP). I used to recommend looking at the valves on the #1 and #6 cylinders, but sometimes it can be difficult to tell by those cylinders only. After looking at the charts below and your valves or lifters/pushrods, you should have it figured out rather quickly.
Valvetrain Movement Reference Diagram
When at #1 TDC you can adjust the following valves:
Intake: 1, 2, 5, 7
Exhaust: 1, 3, 4, 8
Rotate the crank one revolution until the pointer is again at 12 o'clock. This will let you adjust the remainder of the valves. If you did #1 the previous time, you should be now at #6 TDC.
When at #6 TDC you can adjust the following valves:
Intake: 3, 4, 6, 8
Exhaust: 2, 5, 6, 7
Method 2
If you want to set the lash by bringing each cylinder to TDC, watch the valves and the pointer on the balancer and follow the Firing order:
1-8-4-3
6-5-7-2
Adjust both intake and exhaust of the cylinder that is at TDC. You will have to make 2 revolutions of the crank, stopping at 1/4 (90º) turn intervals for each cylinder.
Adjusting Valves and Zero Lash
Zero lash is when you go from having slack between the lifter, pushrod and rocker arm, to the exact point of no slack. The lifter needs to be on the base of the lobe when setting valve lash. When a cylinder is at TDC, both lifters should be at the bottom of their travel (base of the cam lobe).
Gauging zero lash by hand is not an exact science. When setting the valve lash with the engine not running, you can get close enough by doing the "spin the pushrod" method. Loosen the rocker arm until you can feel slack in the pushrod to rocker arm. Spin the pushrod with your fingers while tighening the rocker arm back down. When you BEGIN to feel drag while spinning the pushrod, you are at zero lash. If you don't like the spin method, use the up/down slack method of gauging when the slack is gone. Once zero lash is reached, stop and add your preload. DO NOT go back and try to feel the adjustment again. The lifter will immediately begin to bleed down a little. Tension on the pushrod will relax and this will make it seem like your adjustment did not work. If you want to recheck zero lash, you must loosen the rocker arm nut and tighten it down again while manipulating the pushrod as before. At that point you want to set the preload and LEAVE IT ALONE.
The hydraulic lifter has an internal plunger that has a specific amount of travel. On stock engines, the purpose of preload is to compress the plunger so the pushrod will be riding on a "cushion" (acts like a shock absorber). With stock lifters, turning the rocker nut another ½ to ¾ turn, will normally put you in the ballpark for quiet operation without being too tight and the adjustment should last a long time. Most books show stock preload at up to 1 turn. Specific lifters like the Comp Cams "Comp R's", have less internal travel. ¼ turn preload is more than plenty, with 1/8 or just barely any preload being better for high revving engines. Comp actually recommends .002-.004 preload on a warm engine.
For reference:
3/8" stud: ½ flat = .003472"
7/16" stud: ½ flat = .00416"
Rotating the nut 1/6 of a turn (until the next flat side is in the same position as the previous flat side) is a "flat".
Consequences of improper adjustment:
Too tight - the valves will not completely close and you will lose compression. The engine will run rough, if it will run at all.
Too loose - the rocker arms will make noise from the slack and pushrods could be dislodged. Possible damage could occur from either extreme.
Engine Running Method
Some like to adjust the rockers while the car is idling. If you wish to do this, loosen one rocker at a time until you can hear it click. Tighten the nut, but don't exert downward pressure on the rocker arm with your socket or wrench. At the point when audible clicking is gone, tighten the nut another 1/4 turn (or whatever desired) for your preload (Comp R lifters, less as noted above).
Engine Not Running Methods
There are several methods for setting the lash with the engine not running and are listed below. Read through them all. You might prefer one method over another. They all accomplish the same thing.
Method 1
If you have never had the crank hub off (or know for sure that it's orientation is correct), you can use the arrow that is on the balancer to tell you where you are. You don't have to spin the crank every 90º with this method.
When the arrow is at 12 o'clock you will be at either #1 or #6 TDC. You might have trouble identifying whether #1 or #6 is at TDC when the crank arrow is at 12 o'clock. Probably the easiest way is to look over the other valves or lifter positions. Compare them to the charts below, showing which can be adjusted. Any valve that can be adjusted should be UP (closed) and the lifter/pushrod should be down. Valves that are not to be adjusted will be in varying d ees of being open or DOWN (lifters/pushrods UP). I used to recommend looking at the valves on the #1 and #6 cylinders, but sometimes it can be difficult to tell by those cylinders only. After looking at the charts below and your valves or lifters/pushrods, you should have it figured out rather quickly.
Valvetrain Movement Reference Diagram
When at #1 TDC you can adjust the following valves:
Intake: 1, 2, 5, 7
Exhaust: 1, 3, 4, 8
Rotate the crank one revolution until the pointer is again at 12 o'clock. This will let you adjust the remainder of the valves. If you did #1 the previous time, you should be now at #6 TDC.
When at #6 TDC you can adjust the following valves:
Intake: 3, 4, 6, 8
Exhaust: 2, 5, 6, 7
Method 2
If you want to set the lash by bringing each cylinder to TDC, watch the valves and the pointer on the balancer and follow the Firing order:
1-8-4-3
6-5-7-2
Adjust both intake and exhaust of the cylinder that is at TDC. You will have to make 2 revolutions of the crank, stopping at 1/4 (90º) turn intervals for each cylinder.
Last edited:
dave89iroc
Club Member
unless you are running Comp R lifters
BIGCOWL-IMP
Club Member
Read again i said that :-/
Specific lifters like the Comp Cams "Comp R's", have less internal travel. ¼ turn preload is more than plenty, with 1/8 or just barely any preload being better for high revving engines. Comp actually recommends .002-.004 preload on a warm engine.
Specific lifters like the Comp Cams "Comp R's", have less internal travel. ¼ turn preload is more than plenty, with 1/8 or just barely any preload being better for high revving engines. Comp actually recommends .002-.004 preload on a warm engine.