Technical What would break a rocker? The current state of country music?

My #7 intake rocker is broken. Split around the stud hole.
What might cause it to do that?

I becoming convinced this engine has some sort of evil curse on it.

 

Slot not long enough for lift of cam. Floating the valves. Push rod wrong length so geometry is off.

 

because it isn't a flathead!

 

Worn to the point of weakness.
Hitting the retainer
Stuck valve.

 

Inferior quality part.

 

Fatigue.

Small scratch generated a stress riser which led to a crack.

Fatigue.

 

My reply is based on this as if this has happened more than once. Has it?

 

Along the same lines as @Johnny Gee , may want to mention what was done and used if it’s a fresh-recent build.

 

Sometimes a rocker breaks. Without any obvious reason.

 

Unseen flaws. Unless you abused the engine. And only you know that.

I remember a "Letter to the Editor" in a late '50's Hot Rod magazine.

"Dear Editor.

I was racing my friend's new '56 Ford with my Dad's '56 Chevy. It didn't run well after, so we pulled a rocker cover off to see if we could see anything. It turned out 3 pushrods were bent.

What should I do.

Curious

Dear Curious,

The first thing you should do is hide this magazine from your dad.

Editor"

 

No, lol. Just as the aggravating little things.

I discovered the broken rocker while replacing the intake gasket. Replaced it then. I’m still arguing with the engine over idling again and had the valve cover off today and noticed that the replaced rocker isn’t snugging up. Seems like the lifter isn’t pumping up or something, so I guess the intake is coming back off.

 

Not knowing what type of engine anything we say would be a crap shoot. Did you build it? Did you buy it? What do you know of it's history? I had a small block Chevy that kept breaking a rocker arm and it was because the heads had been milled too much and a valve was hitting a piston. Took a while to figure that out.

 

A bad country song will make any rocker mad but prolly not enough to break them.

 

Coil bind.

 

What the heck is a bad country song?

Ben

 

Peter Gariepy gonna get you, boy!

Ben

 

If it is the same valve breaking different rocker arms, and the push rod isn't bent... It is probably coil bind. Check to see if the spring is weak or needs shimming.

 

Wore out 70s 305 sbc. As far as I know mostly stock, never rebuilt, allegedly has an “rv” cam.

 

If you post pictures of the break, maybe there would be some clues to what caused it.

But it might be easier to just replace it and don't worry about it, but keep a spare in the car.

 

While pictures would help, telling us what engine you have would be a big help. If it is a small block Chevy with press in studs, the stud may be pulling out of the head.

 

the biggest problem to stock small block chevys is not changing the oil... the rockers need the squirt of oil that comes up the push rod... its a metal to metal design and if the push rod plugs with sludge it runs the rocker dry... the constat cold to hot causes the rocker metal to crack... to prove my point, which I had to one time.... I took the push rod and a can of carb clean... and a mason jar.... the push rod was allmost weld ed shut on the top.. and when I sprayed the carb clean in it, it showed straight sludge coming out...
some people never change their oil and think it's not needed...... I would check all the rockers while the cover was off and do the carb clean test on all them.... then I would add 2 or 3 quarts of marvel to the oil and let it ssit and idle.... I'd shut it off when it gets to temp and do it a dozen or so time.... then I would drain the oil, and change the filter... fill it with oil less 1 quart.. and add a quart of marvel...

 

If it's #7 it'll be easy to pull the distributor and remove that lifter from its bore with a magnet, retrieve it from the dist hole and inspect it, replacing if necessary. No need to remove intake.

 

The rocker was tightened too much

 

I’m going with worn parts due to lack of preventive maintenance. I will say even with good PM parts do wear and even had one of my rocker’s on my 283 wear thru the push rod point with good PMs

 

File it under" shit happens" , move on with your increasingly short time here.

 

Coil bind would be my first guess on a newer build . if it has teflon type seals see if one came off and got caught between the retainer and the guide I saw this on a 871 blown BBC recently or if the retainer is hitting the guide . be sure the slot is not hitting the stud

I broke one out of the blue on my 57 Vette running rockers of who knows how old they are with over 30,000 on the second rebuild of the same engine and who knows how many 7000 rpm over revs . It happens now and then .

If its not oiling properly it can get hot and cause issues also . Look for any discoloration

 

@BigJoeArt has recently become an expert on this.

 

Y, UUUUP.

 

This happened recently.

 

I agree. My dad had one break on an OT Chevy wagon around 1977. He never beat on it... well we may have a few times.

Around 1975 my brother grabbed an OT Biscayne with a 283 with a dead miss for cheap money. He dug into the used parts pail and had the busted rocker replaced in about 10 minutes.