Update: removed the driverside valve cover and found TWO rockers loose! When I get home from work I'm gonna tighten them down properly. That should eliminate the "ticking" noise from that bank. Then, just to CMA, I'm gonna do the compression check again. I doubt the loose rockers caused the low compression, but like I said, CMA. Either way, good or bad compression, I'll fire it up again and spray break cleaner to check for vacuum leaks. Hopefully I'll be able to report back tomorrow.

 

I finally wasn't at work AND it wasn't lightning or raining outisde. One of the two rockers I tightened to 25ftlbs and the push rod didnt move and the rocker didnt move. The other rocker I tightened to 25ftlbs and the push rod and rocker were still loose. I decided to do 45° turns until everything was right. At about 180° the bolt let loose. I was super blessed that the entire bolt came out! I was then confused, but I found a "tear" half way through the bolt. So my question is, why was the push rod and rocker still loose? Was the bolt over stretched? Is something wrong with the rocker? I checked the push rod, it is not bent. Also, where can I buy another rocker bolt?

 

If you have a good auto parts store nearby, you should be able to buy a single rocker bolt (or maybe a pair?) at a time. At least that's how it was around here years ago. I haven't had to buy much of that stuff new lately, but I bet the sources are still out there.

If this is normal or not might depend on just how loose they were. For every cycle, there are valves that are open, or at least partially open. Those are going to be tight to the touch because the rocker is under more tension.
During that same cycle there are always valves that are fully closed and so only have the tension set by the spring of the lifter and can feel floppy and loose if you're just rocking them side to side, or rolling them a bit. Normal.
It's if you can raise them up and down on their pivot points and leave a gap between the rocker tip and valve stem tip that's not necessarily normal. Here again though, you might have some that are even looser than normal if the lifter has bled down and it's spring is not as strong as it used to be.
However, being able to raise the rocker tip and socket so there is a gap is not normal and they should always be under at least some tension. But not so much you can't spin, rotate or rock the rocker arm. And even with a good lifter you can exert enough force by hand to compress the lifter spring.

How much slop/flop was there on your loose ones?
If the looseness was at the extreme of what I described, then yes, something was wrong with either the lifter or the valve. Even the rocker could be at fault, but that would be an extreme and you don't usually see broken rockers on these engines. Worn out, yes. But broken? Not so much.
Would not have anything to do with the bolt though, and after that 25 lbs was reached you were never going to tighten the rocker by putting more torque into the bolt. You were already at the max of it's compression, and were only stressing the bolt as you found out. And yes, lucky thing it came out! That's extremely good news!

Anyway, let us know how much play was there you were feeling.

Paul

 

On all of the tight rockers I could spin the push rod but not move it up and down and the rockers felt solid. On the loose ones, I could move the push rod up and down enough it I could see and hear it move. On the same loose ones, the rocker would move side to side and come up off the valve or push rod.

 

Hmm, well that's not good. Being able to turn the pushrods is totally normal as you may know. Sometimes you can even turn them somewhat easily (but with more resistance) when the valve is mostly open and the spring compressed. Just tells you how well the tip fits into the socket.
But being able to move them up and down and hear the clicking is not good and is pointing to some different things potentially. The others with more experience will have to comment, but these are the possibilities that I can think of off the top of my head:

1. The particular valves that are loose need "lash caps" on their valve stem tips to take up space. I would think this is going to show up as every other valve, because on some engines all valves might use them, while on others only every other valve (such as only the exhaust valves for example) are using them. Since some of yours are tight and others are not, this might come up.

2. Valve seat failing. But since our engines don't have press-in valve seats (like aluminum heads would) this should not be an issue. And if the valve seats were in recession, the rockers would theoretically get tighter, not looser.

3. Spring fatigue or the wrong springs.

4. Wrong valves, with short stems on the ones that are loose only.

5. Rocker wear. The fulcrums and inner fulcrum seats of the rockers are severely worn

6. Wrong pushrod length on some but not all.

7 Wiped out cam lobes and/or lifter bases.

But some of these would show up during installation of the rockers. You said you ran the bolts down to 25 lbs, but did you note when the rockers got to zero-lash? And how many turns you went on the bolt after zero-lash to get to the 25lb rating?
If you came down to proper torque and those valves were tight, and they only got loose after running, then there seems to be a wear issue. If they were never at zero lash then any of the above could be the culprit. Or more than one!

I think those are correct anyway. Lots of smart people here that can confirm or debunk any of them.
Good luck.

Paul

 

Paul, I really appreciate all the help. I got a new bolt, torqued it to 25ftlbs, and it still moves. I decided to take the rocker off and inspect it. The "base" and the part of the rocker that is in contact with the "base" seem to have uneven wear patterns. Bad rocker? Here are some links for the vids I posted on YT.

 

While the way you're moving it almost seems to be within the "normal movement" range we were talking about earlier, that is some nasty looking wear and tear on the inside surfaces!
Because the oil grooves are still visible, I don't actually see how it could be worn enough to cause a rocker to loose tension, it's still well beyond the point where the book says to replace it with a new one.

After years of use, there is always some shiny/dully scuffing on those surfaces, but I still say at least in the video yours is due for replacing.
I just don't know if that's the only issue. Oh, did you look into the other side pushrod pocket and the surface that slides on the valve tip? Maybe there's some extra wear there too.

And last but not least, how far does the bolt turn once you've reached the zero-lash point? Or does it ever reach that point? I could not see any real up-and-down movement in the video.

Paul

 

It never reached zero lash. Torqued to 25ftlbs and the pushrod still moves up and down enough to make a clicking noise.

 

Well then, at this point I'd be measuring a few things, but replacing that rocker and fulcrum as well.
I'd take one of the good ones apart and compare things like valve tip height, pushrod length, pushrod installed height at the base circle and peak of the cam lobe (compared to the good cylinder) and condition of the rocker itself. See if anything just sticks out and says "guilty!" between the two.

I'd still replace the rocker, but maybe not before you check it against a known good one.

Paul