Rocker Adjust--Paranoid Questions

[cheburashka]

'74 140HP Mercruiser. I'm installing a new head, and this is my first time adjusting the valves on this engine. I'm used to rockers with a bolt and a locknut which contact the valve stem, so this is strange to me. I've been looking at the Seloc manual and it's kind of confusing. What I've gathered reading the posts on this board is that you adust the lash using the nut in the center of the rocker arm. How do these hold the adjustment? What keeps them from backing off from vibration and pressure? Do they need to be replaced periodically? Mine still fit tight on the stud, but I want to be sure about this.

Second question--Seloc recommends checking the lifter collapsed clearance using tool T711P-6513-A to collapse the lifters. Is there another way to check this clearance? I've kept the pushrods in their original holes, but I want to make sure they line up with the rockers on the new head.

Thanks

 

[Coors]

Re: Rocker Adjust--Paranoid Questions

Hold on, the pro's will come in; but I ain't ever heard of purposely collapsing a lifter, unless you took it apart.

 

[Don S]

Re: Rocker Adjust--Paranoid Questions

If all you are doing is changing the head, there is no reason to even remove the lifters. Put the new head on and adjust the valves. No reason to collapse lifters. The nuts on the lifters are lock nuts and will not back off once you set them.

 

[Haut Medoc]

Re: Rocker Adjust--Paranoid Questions

3/4 turn down from zero lash, & be done with it.....
They will stay adjusted, can't explain why, they just do......
You should invest in a Merc. manual #2......
The collapsed lifter thing sounds like a Ford procedure where you do not have adjustible lifters......​

 

[cheburashka]

Re: Rocker Adjust--Paranoid Questions

Thanks. I appreciate your help.

 

[Don S]

Re: Rocker Adjust--Paranoid Questions

Here is the adjustment procedure from the Merc manual for adjusting the valves with the engine not running.


Valve Adjustment
Engine Not Running
With valve cover removed, adjust valves when lifter
is on low part of camshaft lobe, as follows:
1. Crank engine with starter or turn over in normal
direction of rotation until mark on torsional damper
lines up with center “0” mark on timing tab, and
engine is in No. 1 firing position. This may be determined
by placing fingers on No. 1 valve as
mark. If valves move as mark comes up to timing
tab, engine is in No.4 firing position and should be
turned over one more time to reach No. 1 position.

No. 1 Cylinder - Exhaust and Intake
No. 2 Cylinder - Intake
No. 3 Cylinder - Exhaust
No. 4 Cylinder - Intake

2. With engine in No. 1 firing position as determined
above, the following valves may be adjusted:
3. Back out adjusting nut until lash is felt at push rod,
then turn in adjusting nut until all lash is removed.
This can be determined by moving push rod upand-
down while turning adjusting nut until all play
is removed.
4. Hydraulic lifters now can be adjusted by tightening
adjustment nut an additional 3/4-turn. Valve
lash should be checked after engine has run and
reached operating temperature.
5. Crank engine one revolution until pointer “0” mark
and torsional damper mark are again in alignment.
This is No. 4 firing position. With engine in
this position, the following valves may be adjusted:

No. 2 Cylinder - Exhaust
No. 3 Cylinder - Intake
No. 4 Cylinder - Exhaust

6. Install distributor cap, spark plug wires and coil
lead.
7. Install rocker arm cover; torque to 40 lb. in. (4.5
N?m).