View Full Version : Torquing rocker arm bolts on LS1


TomXTC
05-18-2012, 06:13 PM
I am about to install a Comp Cams trunion bearing upgrade kit in my 98 TA WS6.
In reading instructions and watching the videos they just torque down the rocker am bolts all at the same time regardless of what position they are in.

I am awaiting the factory shop manuals I just ordered but have read a thread here and got some advice from a member on a different thread.

It seems to me that if one torques down the bolts while the valves are in a different position (open or closed) there will be a different amount of tension on the valve spring so when that valve moves the torque on that bolt will not remain consistent.

Some on different thread on this site claimed they had just torqued the bolts down the torque measured the same even after the motor was rotated. Others thought that was a bad idea as it could lead to loose rocker arms. I am awaiting the manual to see what it says.

What is the risk of not torquing the bolts when the valve is in the closed position?

If I am going to go ahead and take the time to torque them down when the valves are in the closed position what is the easiest way to see that they are indeed closed when turning them by hand? In other words a fast way of rotating the motor 360 degrees?

It seems that the suggestion by another member here as to torquing down the bolts which takes only two steps and one rotation of the motor 360 degrees is the smartest way of accomplishing this. I pasted his response below.

Originally Posted by transamtom
To make it easier for you you can tighten 1/2 of them after you turn the engine to TDC.

Then turning the engine over by hand another 360* you can do the second 1/2.

From TDC

Tighten Int 1,3,4,5

Tighten Exh 1,2,7,8

Turn 360*

Tighten Exh 3,4,5,6

Tighten Int 2,6,7,8

All 22lb ft.


Thanks much.

sreve
05-19-2012, 07:47 AM
What is the risk of not torquing the bolts when the valve is in the closed position?


compromising or pulling the treads out of the head

I put the car in the air it can be barred over easily from the bottom

TomXTC
05-19-2012, 10:13 PM
That is certainly more than reason enough to do it correctly.

I think I worded my question poorly. I am waiting for my factory manuals to arrive which I am sure would have the answer but wanting to get this done and being the only part I am unsure of thought I might find a quick answer here.

What I meant was how to make sure the valves are in the closed position without having to do something like check the marks on the timing gears to see where TDC is.

I don't have a lift, just a tight garage I am borrowing as mine is full and not even a flat space for the car. I will have to be in and out faster than if I were at my own place. I have the bearing upgrade kit and all the tools I need etc. all ready. Just want to know this before getting to it.

GMtechmatt
05-21-2012, 06:56 PM
.

Rotate the crankshaft until the number one piston is at top dead center (TDC) of the 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.







The engine firing order is 1,8,7,2,6,5,4,3.







Cylinders 1,3,5, and 7 are left bank.







Cylinder 2,4,6, and 8 are right bank.


Notice: Refer to Fastener Notice in Cautions and Notices.




7.

With the engine in the number one firing position, tighten the following valve rocker arm bolts:


Tighten







Tighten the exhaust valve rocker arm bolts 1,2,7, and 8 to 30 Nm (22 lb ft).







Tighten the intake valve rocker arm bolts 1,3,4, and 5 to 30 Nm (22 lb ft).






8.

Rotate the crankshaft 360 degrees.





9.

Tighten the following valve rocker arm bolts:


Tighten







Tighten the exhaust valve rocker arm bolts 3,4,5, and 6 to 30 Nm (22 lb ft).







Tighten the intake valve rocker arm bolts 2,6,7, and 8 to 30 Nm (22 lb ft).

TomXTC
05-21-2012, 09:29 PM
Yes, thanks. To find TDC isn't it easier to just use a piston stop or something in the spark plug hole rather than taking the timing cover off?

KILLER-LS1
05-23-2012, 12:25 PM
dont take the timing cover off. pull out the spark plug, and cover the hole with your finger. have a friend crank it over by hand slowly, and youll feel a burst of air pressure when the piston is a TDC. This also ensures both the intake and exhaust valve are closed.

TomXTC
05-23-2012, 05:32 PM
dont take the timing cover off. pull out the spark plug, and cover the hole with your finger. have a friend crank it over by hand slowly, and youll feel a burst of air pressure when the piston is a TDC. This also ensures both the intake and exhaust valve are closed.

Thanks that is what I was getting at. It finds not just TDC but TDC on the compression stroke. I found a thread here talking about different ways of doing this. If one is doing some other procedure then using the timing gears is great but otherwise it seems to me to be unnecessary when there are alternative methods.