Why do I keep breaking rocker arms?

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Looks like a stepped bolt. The cups are close to 7/16" by my measure, and I measured almost all of them. Also a sh***y picture of adjuster and cup. Shoulda taken more of this one. I ran the engine but couldn't get a shot of the rockers and keep it from stalling out at the same time.

All of this is happening while I'm still driving the car. Despite this discussion it's a total blast to drive, and it's also, other than my work truck, my only vehicle. Since I'm being forced to drive like a gentleman, I'm appreciating how smooth and responsive the car is since the new distributor and tuneup.

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So the cups are 7/16" diameter at the top? The widest point?
 
So the cups are 7/16" diameter at the top? The widest point?
Well, those are about the same as mine then. I was thinking maybe it's not that His cups were too big, but His balls were too small, :p
Guess it's just another phone cam illusion.
 
Looks like a stepped bolt. The cups are close to 7/16" by my measure, and I measured almost all of them. Also a sh***y picture of adjuster and cup. Shoulda taken more of this one. I ran the engine but couldn't get a shot of the rockers and keep it from stalling out at the same time.

All of this is happening while I'm still driving the car. Despite this discussion it's a total blast to drive, and it's also, other than my work truck, my only vehicle. Since I'm being forced to drive like a gentleman, I'm appreciating how smooth and responsive the car is since the new distributor and tuneup.

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Be careful with the torque on that bolt. Since it's a smaller thread than the rest, the torque spec is lower. The thread size on that I believe if I remember right is only 5/16. That means torque spec is light at around 15LB FT, I don't CARE what the book "says", so watch it! If you break it, they are HARD to find!
 
Well, those are about the same as mine then. I was thinking maybe it's not that His cups were too big, but His balls were too small, :p
Guess it's just another phone cam illusion.
Sounds like his personal problem, not ours! lol
 
Any updates on this???
At the moment I'm just enjoying having the car back and am daily driving it (you know those 40 mile scenic routes to the grocery store). I'm carefully watching the tach, shifting at 3000-3500, waiting for the next broken rocker I guess. I'm a little obsessed with how loud the rockers are under the valve cover and am always visualizing them just getting ripped apart by too long pushrods but I have no sane reason or enough knowlege to back this up. Can anyone tell me how to post a video here of the rockers in action/engine sound like Rusty's YouTube video?
 
At the moment I'm just enjoying having the car back and am daily driving it (you know those 40 mile scenic routes to the grocery store). I'm carefully watching the tach, shifting at 3000-3500, waiting for the next broken rocker I guess. I'm a little obsessed with how loud the rockers are under the valve cover and am always visualizing them just getting ripped apart by too long pushrods but I have no sane reason or enough knowlege to back this up. Can anyone tell me how to post a video here of the rockers in action/engine sound like Rusty's YouTube video?
You have to host your video to a third party site like youtube and then post the link here.
 
At the moment I'm just enjoying having the car back and am daily driving it (you know those 40 mile scenic routes to the grocery store). I'm carefully watching the tach, shifting at 3000-3500, waiting for the next broken rocker I guess. I'm a little obsessed with how loud the rockers are under the valve cover and am always visualizing them just getting ripped apart by too long pushrods but I have no sane reason or enough knowlege to back this up. Can anyone tell me how to post a video here of the rockers in action/engine sound like Rusty's YouTube video?
Would you like a video of mine under the hood so you can compare engine noise?
 
I figured I'd post an update to this debacle. About two weeks after the above post I had to take Val back into the shop as she wouldn't keep running, which turned out to be a loose wire (I've just got to learn something about classic automotive mechanics!!). In the process of diagnosing and fixing that ten minute job the machanic noticed that the engine 'didn't sound quite right' so he pulled the valve cover and -surprise!- a broken rocker. I had been regularly driving, no hot rodding or anything. So I left the car for them to figure out the issue.

I just got it back yesterday. They tried everything they could think of and finally just pulled the engine and tore it apart. It turned out that the idiot subcontractor in Texas that did the rebuild had used mismatched lifters on two of the cylinders -the two that kept breaking rockers. So now I have a new set of matching stock lifters, new aluminum roller rockers, a replaced oil pump (they found a crack) and a new balancer. All under warranty. Part of me feels bad for the shop, part of me feels like they deserve it for subbing out work. I'll still be looking for a new mechanic in the area. I mean, it took four months.

The good news besides the problem being (hopefully) solved is that the car runs and sounds like a dream. The loud clattering noise is replaced by a much quieter sort of buzzing sound and I can actually hear my cool exhaust system now, and my stereo as well as long as I'm driving under eighty or so. Much better acceleration especially from a dead stop and on hills as well. So I guess Santa is real after all.
 
Good to hear a decent result after the trouble you've had...

As Killer6 mentioned that pushrod/rocker was a serious problem...

Your "mechanic" should have spotted that easily... I'm guessing the guy that worked on it this time wasn't the one who worked on it before...

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