Had a rocker loosen up, now I've got a bad tick. Need troubleshooting ideas.

[CueBall]

My Camaro only has about 20 miles on it since I rebuilt it completely several years ago. I successfully dyno tuned the car on Saturday and everything was great. Good power, got the carb set nicely, timing was all set, etc. I took the car for a test drive on Sunday and only made it about 20 miles before I had a problem. Going slowly through town when power dropped off and the car seemed to be running short a cylinder. Pulled over into an empty lot and heard a racket from the passenger side. Shut it down as soon as I could (maybe 5-6 blocks?) and pulled the valve cover to find that the nut holding the #6 intake rocker had come loose (the allen securing pin had backed almost all the way out). Pulled the rocker and it has some minor damage from the pushrod and valve tip, but nothing too bad. The pushrod itself is still perfectly straight and both ends look good. Put everything back together and limped it home, then pulled things apart again. Reset the lash on all the valves (it's flat tappet hydraulics, so I set them all to 1/2 turn past "snug" on the pushrod) and double-checked all of the allen retainers. But it's still noisy. I tightened up the header bolts and collector bolts, just to make sure that wasn't the problem. But the noise seems to be coming from the #6 cylinder area.

I can see through the heads (AFR 180cc) down into the lifter valley and the lifters on both intake and exhaust look good. They're not collapsed, and I can't press the plungers in by hand, so they seem to be okay. Pressing on the rockers while the engine is running doesn't seem to make a difference in the noise. Both rockers are moving well, so it doesn't look like a wiped cam lobe either. Since this was the intake side that failed, I wouldn't think any cylinder damage would be done. If anything, the cylinder should have been trying to fire with not much A/F mixture in there, since the intake valve wasn't opening all the way (or maybe at all).

I'm struggling to think of anything else to try before taking the intake (and possibly head) off the engine. I'm really hoping to take this car on Power Tour in two weeks, and if I tear apart the engine now I'll never get it back together in time. Maybe try running the engine with both rockers off and the spark plug out, to see if the noise goes away? Is there some other culprit that I'm not thinking of? Something else that could be wrong with the lifter that wouldn't be apparent? What are the chances something this minor did internal damage to the valve/cylinder/cam?

[corvettedad]

Had a similar issue and actually had a bad rocker arm stud, it was somewhat flat on one side but with a jam nut I would think yours would stay put? I couldn't see it till I took it off, and they were new heads. That's the only issue I've ever had out of many engine build's. Another thought is a bad spring ( broken ), I've learned just like a lot have" just because it's new " yeah it could be bad. Quality control is not what it used to be. Good luck!

[CueBall]

My best guess is that the jam nut wasn't tight enough and loosened on its own. I made sure all the others were extra tight when I reset them.

The spring isn't broken and seems to be fine. I was able to watch it work while the engine ran with the valve covers off. The studs also look fine (both the spring and stud are visible in the third picture in the original post). I also realized that it can't have a bent valve because 1) the valve wouldn't have been opening if the rocker was off, and 2) I had my girlfriend help me with resetting all of the rockers last night by bumping over the engine and using my finger to feel for the compression stroke. I felt the pressure come out the spark plug hole, so I know compression is good. It felt the same as every other cylinder (I did them all).

I ordered a replacement rocker today, but they appear to be backordered from the factory. Summit is supposed to call me tomorrow with an update as to whether they can get one faster or not. I could get a similar (but slightly different) arm, if need be.

I just can't think of what else could possibly be causing the tick since everything visually seems to be okay. Oil pressure is good and I have no reason to think it's a bearing problem or anything like that. So, I'm stumped. Will probably have to pull the intake and check the lifters and cam up close, but the lifter seems fine from what I can see so far.

[anotheridiot]

To me it looks like the pushrod was never in the cup on the rocker, from the wear on the aluminum and the line on the rocker on the opposite side. Looks like it was always crooked. After or during the dyno the pushrod slipped into the cup and started to rattle everything loose.

Thats what I see anyway, so I would not be overly worried about the rest of the adjuster nuts, I would think if any others were not seated they would have gotten there by now.

[CueBall]

I actually was able to fix the problem last night. Turns out one of the rockers on #8 was also loose, so it was causing noise. Because I had the issue with #6, I hadn't thought to check #8. I ended up redoing the preload setting on ALL of the rockers again last night, this time using the EOIC method. That fixed the issue completely. I'm going to replace the damaged rocker anyway though. The damage isn't bad at all, but it's cheap insurance. Singles are backordered from the factory though, so replacement might have to wait a month or two.

[anotheridiot]

I actually was able to fix the problem last night. Turns out one of the rockers on #8 was also loose, so it was causing noise. Because I had the issue with #6, I hadn't thought to check #8. I ended up redoing the preload setting on ALL of the rockers again last night, this time using the EOIC method. That fixed the issue completely. I'm going to replace the damaged rocker anyway though. The damage isn't bad at all, but it's cheap insurance. Singles are backordered from the factory though, so replacement might have to wait a month or two.

I am just looking at the dimple that removed the anodize off the pushrod side. I have been there before with these rockers and making sure the pushrod is in the hardened insert. Just seeing the dimple makes it look like it started on the aluminum.

what are they charging you for the replacements by the way? Not really happy with the stamped steel roller tips we are running.

[CueBall]

I am just looking at the dimple that removed the anodize off the pushrod side. I have been there before with these rockers and making sure the pushrod is in the hardened insert. Just seeing the dimple makes it look like it started on the aluminum.

I'm 100% positive that the pushrod was seated correctly to begin with, because I was really careful during assembly and the car ran well for about 50 miles, including nearly a dozen dyno pulls. But once the allen loosened, the locknut loosened and the pushrod started bouncing out of the seat.

what are they charging you for the replacements by the way? Not really happy with the stamped steel roller tips we are running.

A single replacement rocker is only about $20. A full set of 16 is about $250. I went with these specifically because I'd heard so many guys have problems with stamped steel versions.

[anotheridiot]

I'm 100% positive that the pushrod was seated correctly to begin with, because I was really careful during assembly and the car ran well for about 50 miles, including nearly a dozen dyno pulls. But once the allen loosened, the locknut loosened and the pushrod started bouncing out of the seat.


A single replacement rocker is only about $20. A full set of 16 is about $250. I went with these specifically because I'd heard so many guys have problems with stamped steel versions.

Yeah, stamped steel were ugly, ended up changing the locks since the one they supplied did not eve allow a socket to go around without interfering.