OK, I think these questions are generic for any aluminum roller rocker, I'm using PRW recommended by my machine shop, but would thik this hold true for a Summit, Jegs, or other builder/shop brand.

1) When putting the rocker on the stud is there a top and bottom to the trunnion shaft?

2) Is is normal that some will not go onto the studs far enough to catch the nut until you rotate the motor and get closer to TDC for that cylinder? Maybe 1.6 like these are bit tougher due to the ratio?

3) Also it is normal the the rocker will not bottom out on the stud... I don't think it can and still operate properly.

I have just got them on but not yet adjusted, I wanted to make sure before going to the next step! Here is what we've got so far.



Sorry if these are dumb questions but it's been about 20 years since my last job like this and first with the roller rockers!

 

If you look at the RR where the stud goes thru, you will find one side is flat...this side up!! You need the flat surface for you lock nut to snug down to.

Adjusting valves on the 1985 Corvette: also if you follow this sequence you can remove the rockers and install the RR as you adjust the valves. If you remove a rocker that is under tension because the valve is open, you may not be able to get any threads of the nut on the stud. The valve needs to be CLOSED.

1) Remove the spark plugs. This makes it much easier to turn the engine by hand.

2) I believe that the nut in the center of the bottom pulley on the balancer is 5/8”. Use a six point 5/8” socket to turn the engine over by hand to line up the timing marks. Place a finger in the spark plug hole for plug #1 as you turn the engine over. You are trying to determine if the engine is on compression as you line up the marks. If you feel the air pushing against your finger as you line up the marks, you have compression in cylinder #1. Align the timing marks.

3) Now adjust the valves as follows:
Intake #1, 2, 5 and 7 then adjust Exhaust 1, 3, 4 and 8.

4) Turn the engine 360 degrees and line up the timing marks again. Now adjust the following:
Intake 3, 4, 6 and 8 then adjust Exhaust 2, 5, 6 and 7.

You are now finished with your adjustment. I usually tighten the lock nut ½ turn after adjusting to zero lash.


The rocker should NOT bottom out on the stud, but be held off the base of the head (rocker stud).


Try this method for adjusting using the above sequence per Forum member Joe C:

BTW, I tried something a little unconventional on adjusting hydraulic lifters. one thing that always bothered me is the statement "spin the pushrod until resistance is felt" that seems a little too subjective to me. so I tried this: I set "zero" lash with a .0015" feeler gauge while slowly turning the adjusting nut. when I felt the feeler gauge grab, I was fairly confident I was about .001 from zero lash. at that point, I turned the adjusting nut 3/4 turn. I recently read that one turn is equivalent to .040" because of the thread pitch on the threaded rocker arm stud, so 3/4 turn should give you about .030" adjustment. I also read that within a hydraulic lifter there is .060 total plunger movement, and ideally you want to be just about in the middle of that range, or .030 inch. I don't know if I’m out in left field on what I did, but I feel I got a really consistent valve adjustment across the board. if you think you might have a tight cylinder, maybe give this a try - it seemed to work for me...

I have used it several times and it seems to work for me better than twisting the rods....and I have been doing this for 35+ years..

John

 

John, thanks for the input! I thought I needed to check on the flat spot of the trunnion shaft before going on. I'll go back and check those and get those right.

I've already got the balancer marked so I can rotate to the 4 locations and get each cylinder at TDC for adjustments, and plugs are not installed yet. I did notice that you can't get a nut onto a valve that is open, so rotating the assembly takes care of that.

 

I believe the 85 and 89 can be adjusted the same. Takes only one full rotation to get all the valves. You can check it by turning the balancer and lining up the timing mark and see which valves are closed and compare to the above sequence.

I just replaced all my rocker studs with ARP studs last weekend and used the sequence that I listed above and Joe C's method of using the feeler gauge. Did them all in about 45 minutes. That means taking off the RR, taking out the stud, replacing with new ARP, put on RR, tighten nut to get to zero lash, 1/2 turn and lock the lock screw....repeat 15 more times.

John

 

I don't get the process with the feeler gauge, where are you putting the gauge? The rocker arm is concave for the tip of the push rod so it can't be there. and the rockers are self aligning so I don't think you could measure in there?????

Don't get this part of your process. I agree though the "spin the push rod until resistance" is a very subjective method.

 

Put feel gauge between roller tip and the top of the valve. On your picture, the end where the spring is. Turn the nut as you pull on the gauge (at a right angle to the roller so you are pulling to the front or rear on the engine). When you feel resistance you have reached zero lash plus .0015". The .0015 is nothing.....tighten the nut 1/2 turn and then lock down the allen screw inside the nut.

 

Lets not make this harder than it is. Since you have the intake off, all you have to do is rotate the engine until the valve you are adjusting is on the base circle.

 

I'm doing this! Also put the mark on he balancer as a second check!

The issue with the feeler gauge is space on the roller tip to fit it. Like I said these are self aligning so there isn't a flat area under the rocker to fit the feeler gauge. Maybe you have a gauge that was a narrow end, my gauges are about 1/2" wide metal strips.

 

go to sears, they have a feeler gauge set that is about 5/32 wide.

 

I think the quicker solution for me will be a pair of snips to narrow the one gauge I need and then no trip to sears

I get the idea now, and I'll give that a try.

 

If you are only using a feeler of a few thousands just cut it with a good pair of sharp scissors.
BTW I have used the method John Marker described for over 30 years. It only requires one revolution of the engine. It is also the method that is in your FSM

 

That's my plan.

 

I'm glad I asked about the flat side of the rocker axle as upon review about 10 were wrong, even with a 50/50 shot. Thanks for getting me quick info on that. Well, just adjusted the valves and used the feeler gauge method and rotating the engine just once.

I was wondering if now doing a compression check was a good way to check my work? I'd like to know know if something is wrong instead of waiting until all is back together.

 

You should not have to cut down your feeler gauge. I don't think that the self aligning RR are an issue. They should still have the roller riding on the flat surface of the valve stem. You should have two flat surfaces at this point, although the roller is round...it is flat against the valve stem. This should not distort the gauge at all.

Give it a try on a valve and see what you think.


John

 

The issue was the width of my feeler gauge, it was about 1/2 wide, that would hit the self aligning sides and make it tough to fit in and be accurate.

I just snipped the end more narrow and that worked.