Pushrod/rocker arm install

[gnxtc2]

I have to remove the rockers to change the valve springs and pushrods. At the same time, I'm going to install studs which require me to remove the injectors. I will be rotating the motor to bring each piston to TDC for valve spring R&R.

On re-assembly of the rocker arms, I read that the motor needs to be at the 11 o'clock position.

My question(s):
- Is the 11 o'clock position when the CPS tang is lined up with the mark on the balancer? Also there is tab somewhere at the 4 o'clock position, were is this tab to verify compression stroke?
- Does it matter if it's on the compression or exhaust stroke?
- I'm assuming that on compression stroke, #1 intake and #1 exhaust valves are closed. What valves would be open/closed on exhaust stroke?

Billy T.
[email protected]

 

[Tom S]

Seems more logical to me that you are just wanting a lifter to not be up on a lobe is all. This makes no sense to me.

 

[Powerstroke Cowboy]

Billy When I do valve springs I never even put each cylinder to TDC All I do is take the spring off and put the new one on. It is a good practice to do it though. I just have never had a need to. If you are careful to make sure not one cylinder is TDC then the valves can not fall all the way in. Then you just pull them up and carefully put the new spring on. It saved me a lot of time this way. As for the 11 o'clock position that is not needed either. That would just make it more easy to put the rocker arms back on. All I do there is keep them even is a tighten the bolts up.

hope this helps!

 

[Patrick Feeley]

Putting the motor in the 11 o'clock position is to avoid lifter jacking (the lifter pumps up with residual oil pressure when the rocker/pushrod is removed). If the pushrod and rocker are installed with a pumped up lifter, you can get engine damage when the engine is turned over. In the 11 o'clock position, an oil drain path is provided so the lifters don't pump up. It may not be a problem if the engine has not been operated for a while, but it only takes a second to put it there and not take a chance. Cheers!

 

[Tom S]

Putting the motor in the 11 o'clock position is to avoid lifter jacking (the lifter pumps up with residual oil pressure when the rocker/pushrod is removed). If the pushrod and rocker are installed with a pumped up lifter, you can get engine damage when the engine is turned over. In the 11 o'clock position, an oil drain path is provided so the lifters don't pump up. It may not be a problem if the engine has not been operated for a while, but it only takes a second to put it there and not take a chance. Cheers!

I am not understanding how this allows the motor to drain. I am also not understanding residual oil pressure.

 

[Patrick Feeley]

When the motor is running and there is oil pressure, some of that pressure could remain inside the hydraulic lifter(s), unless of course the engine just happened to stop in the 11 o'clock position. When the rocker/pushrod is removed, the lifter will expand (or "jack") due to the pressure trapped inside. I've never traced all the oil passages or anything, but when the engine is in that position, the lifter passages must line up allowing the oil (pressure) to bleed off. The positioning is specified in the service manual to avoid engine damage. Not sure that is all that helpful. Cheers!

 

[Chvyrkr]

The ford engine manual instructs the mechanic to put that timing mark at 11 o'clock prior to installing the valve train "to prevent damage."

Having installed both ways...

With the timing mark at 11, all rockers bolted down easily. I didn't have to pull any rockers down to the head with the bolts.

Without lining anything up, there were a couple rockers that didn't want to sit flush, and I cranked the motor over until that particular rocker sat flush, then bolted it.

I'm not sure what you could damage if you didn't roll the motor over and used the bolts to pull the rocker down. I doubt seriously that the static lifter pressure would overcome spring pressure, and cause piston to valve contact or something of that nature.

But, it's generally considered bad juju to use the threading action of a bolt to seat a part so...

If you can't set the timing mark to 11, just roll the motor as you work so you can seat each rocker flush before you bolt it down. You'll be fine.

 

[gnxtc2]

For the 11 o'clock postion, the mark on the balancer lines up with the tab on the CPS?

I guess it doesn't matter if #1 cylinder is on the compression or exhaust stroke.

Billy T.
[email protected]