Roller Rocker adjustment

[rrudholm]

OK, I adjusted my roller rockers 1/2 turn past zero lash. My car runs like its not on all cylinders. I did the cylinder balance test and the codes told me that 3,4,5,6,7, and 8 are weak. I did a compression test on cylinders and seen around 130 psi
on all cylinders. This number is low but I'm thinking the Roush 200 heads with large intake runner my be a factor. I pulled the valve covers off and turned the engine over to bring the oil pressure up and then looked at the valve tarin. I can spin the pushrods on closed valves fairly easy. With this said, I don't think the valves are being held open. Is it possible that the valves are not opening far enough. Maybe I need more pre-load? Anyone have any idea's

 

[final5-0]

OK, I adjusted my roller rockers 1/2 turn past zero lash. My car runs like its not on all cylinders. I did the cylinder balance test and the codes told me that 3,4,5,6,7, and 8 are weak. I did a compression test on cylinders and seen around 130 psi
on all cylinders. This number is low but I'm thinking the Roush 200 heads with large intake runner my be a factor. I pulled the valve covers off and turned the engine over to bring the oil pressure up and then looked at the valve tarin. I can spin the pushrods on closed valves fairly easy. With this said, I don't think the valves are being held open. Is it possible that the valves are not opening far enough. Maybe I need more pre-load? Anyone have any idea's

You don't tell us if you are working with ped or stud rockers but never the less ... I would guess you are not finding true zero lash and may be going beyond it which could cause an issue for you.

You can spin the pr's when the valves are properly adjusted so that is no kind of valid test.

Try to lift the pr up and down as you close the gap. When all slack is gone, you are very close to zero lash.

When you spin the pr with your fingers until the moment of zero lash is found, the amount of additional resistance to spin it is very very subtle.

To properly set your valves, it takes a very focused effort of concentration and delicate touch. You just have to kinda develop ... a feel for it.

I can show peeps all day long how to do it
but
to explain it over some puter screen

about the amount of pre load ........

1/4 to 3/4 turn is the range for most street applications with 1/4 making a tiny bit more power while most likely making more noise. The range of 1/2 to 3/4 will produce the most quiet operation.

Grady

 

[WhiteDevil]

Yeah i turn mine to in between 1/2 and 3/4 and that has worked great for a while now. Let us know whether you are working with stud or ped mount heads becaues that does make a difference.

 

[95Vert]

needed info. subscribed....

 

[R.J.]

Try setting them like this:

With the piston at TDC with both valves in the closed position, do the following:

The first thing you want to do is verify zero valve lash. The best way to do this is to wiggle the push rod up & down as you tighten the rocker arm nut. At the point where the push rod no longer moves up & down, That is zero lash. You now have a starting point for verifying “true” zero lash & the lifter pre-load.

When you adjust the valves you are setting the lifter pre-load, Pre-load is the amount of distance the push rod seat (or “cup”) moves away from the retaining clip.

To set true zero lash & the lifter pre-load, We are going to follow the “EO / IC” procedure.

What is “EO / IC?

EO, is Exhaust Opening; IC, is Intake Closing.

We have the piston at TDC (Both valves are in the closed position), Rotate the engine in the normal direction of rotation (clockwise, if you are facing the front of the engine).
You will see the exhaust valve just starting to open, stop rotating the engine & back off the intake rocker arm.(You are going to back off the rocker arm & re-verify for true zero lash, As you are now positively on the base circle of the camshaft whereas the previous lash adjustment was just a pretty close ballpark guess.) You will once again wiggle the push rod up & down as you tighten the rocker arm nut. When all up & down movement is gone, tighten the rocker arm nut ½ turn, tighten the hex head set screw until it bottoms out on the rocker stud, tighten the rocker arm nut ¼ additional turn. You have now set the lifter pre-load at .045”.

Rotate the engine, You will see the exhaust valve fully open & then close. Watching the intake valve that you just set, You will see it open, You want to keep rotating the engine until it fully opens & then starts to close. When it is almost closed, stop rotating the engine. Set the exhaust valve the same way you did the intake valve.

Move onto the next cylinder in the firing order…

 

[rrudholm]

Well, I found my problem. Cylinder number 7 with "0" compression. The weird thing is, I pressurized the cylinder with my air compresor to try and hear where the air was going and it pressurized up to 120 psi and held but turning the engine over will not even produce a puff of air
NOT GOOD. I'm thinking the piston is just setting there without a connecting rod attatched. I'm not hearing any parts banging around like you would think. I'm going to have to pull the pan and take a look. I knew I should have bought a crate engine.

 

[WhiteDevil]

Well, I found my problem. Cylinder number 7 with "0" compression. The weird thing is, I pressurized the cylinder with my air compresor to try and hear where the air was going and it pressurized up to 120 psi and held but turning the engine over will not even produce a puff of air
NOT GOOD. I'm thinking the piston is just setting there without a connecting rod attatched. I'm not hearing any parts banging around like you would think. I'm going to have to pull the pan and take a look. I knew I should have bought a crate engine.

I wouldnt go pull the oil pan just yet. YOu never answered us with what kind of heads you have pedestel or stud. Also if your piston was disconnected from the connecting rod or anyhting like that then there would be a **** load of noise.

 

[rrudholm]

Roush 200 heads w/ Crane Cams roller stud mount rockers. OK, I stuck a straw in the spark plug hole on this cylinder and had my wife turn over the car. I feel the piston moving up and down but no compression. I re-adjusted the Rockers on this cylinder but still not good. I can hook an air compressor to this cylinder and bring it up 120psi and it will hold it but, by turning the engine over I can not create any pressure. WHAT?