My 327 has a broken rocker arm stud. I was driving along at a good speed then slowed down in a small community. Heard a knocking, it quit, started back, quit started back and I pulled off the road. A friend of mine last week said he heard a ticking like a hydraulic lifter was leaking. I can't hear good and I have never heard it. I was turning on the carburetor and did not hear it. Got it home and pulled the cover, Saw a rocker arm out of place, I just figured it just fell off the valve and pushrod. I went to straighten it and picked it up. The arm beside it is very loose. I know I got to take off the head and have a new stud put on. I assume I need to replace the lifter. Do I have to replace all the lifters.? I hope that is all I have to do as I am not prepared to pull the engine. What do you think?
I believe the broken stud can be drilled out, the hole tapped and a replacement stud screwed in. Care must be taken to prevent chips from dropping into the pushrod holes. 4TTRUK
Yeah, maybe it could be drilled out without taking the head off. I sure I could not do any more damage than has been done. If I cannot drill it out, then I would have to take it to a machine shop thanks for the good news!
Not sure about your overall problem but I'll recommend this part of it, take both heads to the machine shop and have the screw-in studs & guide plates done and never look back. You can stay with the 3/8" rockers but I would toss those as well. Either stud diameter you choose the the bottoms are the same thread, 7/16-14. Just my opinion, have been a long time doing this "stuff". I would try to find the reason it broke, there are usually underlying causes? Thanks, Gary in N.Y. P.S. Before you attempt a "home-repair" I would make certain you have a "spare" head closeby! Drilling those studs by hand is no picnic, and even with most of it removed the pressed shell remaining is in there fairly tight and usually fairly deep.
The break is very clean, flat across below the top of the stud hole. If I have the screw-in studs & guide plates done, do I have to do both heads The motor has little miles on it. e
Had this happen to me also. As I had another set of heads I wanted to redo I just wanted to get going again. I drilled and tapped the broken stud 1/4-20. Got a socket head cap screw(hard) and tried to pull it out by stacking washers with a nut on top. Could not move it. I have heard you can drive them through. I drove it down a little which loosened it then it pulled out easy. Drove another new one in with lock tight on it and worked fine until my new heads were done.
No you don't have to do both heads, BUT you already have the intake off to pull the one head, whats to say another stud on the other side isn't going to break. Cars cost money you can't alway cheap out and win. If you can't do BOTH heads now, park the car until you can. You asked and got some answers now save up your money. Pat
Why do you think it broke ? Bind, sticky valve, bad geometry, something else like it was just time for that stud to give up and check out? You'd be way ahead of the game to do both sides while the engine is down and apart.
I've learned Studs don't just brake because they get old. That's the result of another issue. Your friend was most likely giving you the heads up there is an issue inside. If you stop at the broken stud you'll probably be on the side of the road again very soon. The Wizzard
--Some but not all the studs can be driven into the water jacket in the head. I did an emergency repair on the way down from Seattle in the late 60s , a tired old 283 that developed a "ticker" that just couldn't be adjusted to get the lash out of it. I found the rocker arm had cut a groove in the side of the stud , the valve stem was also rounded off above the keepers . I tried to use the spacer method to jack the stud out but it sheared off. I got lucky as that stud could be driven thru . I dressed the stem the best I could , drove a good used stud in and replaced the rocker/ball/lock nut and went on my merry way.
Pull both heads. And like guys here said find the cause of the failure. I have seen engine builders ignore valve train geometry. Smokey's book has some good info on geometry. Look at page 87 and 88. Good information for roller tip rockers, but is good for stamped rockers as well. It does not take much to throw off geometry fairly significantly leading to problems and failures.
Oh yeah, I think something else is going on. I positioned the rocker arm over the valve and push rod. The top part of the stud would not go all the way to the broken end of the stud by a good margin. I have not messed with the stud bolt. Seems like the rocker arm may have been tightened down too much. It did not seem to miss any before. as a matter of fact, it had great acceleration. If it was too tight seems like it would miss some. It also bothers me that the rocker arm on the adjacent valve is also loose. I appreciate the help you guys are giving me and I will be here alot until I get it wrapped up.
it is not a race car with stiff springs, so replace as others have said and pin all of them and you should be fine---loose and broken studs are usually associated with adjustment neglect...
Absolutely, even later in the performance SB's, G.M. had the common sense to install these on all the "good" builds. The only one they "missed" was the "DZ" unit. Thanks, Gary in N.Y. P.S. Pinning the studs really isn't "connected" to breaking them, it will keep them in, that's it! You need to find the cause, even doing the studs/plates, things need to be correct. It really could be "fatigue", in which case they all need to go anyway, but that's a stretch. You just never know what the heads have been subjected to, I've seen them cleaned in an oven (Bayco) and ruined the studs.
I doubt your real issue started in the heads. Check your cam and lifter. A lobe going down will loosen the adjustment (your friends comment) letting the pushrod float out of place. Pushrod out of place on the outboard tip of rocker (TRYING TO GET OUT) can coil bind the spring. Then it's a fight between what's the better piece, the pushrod or stud. This is just 1 of several things that could have happened. Find your real problem, fix it. Then take care of the end result. Or, as said before you'll be on the side of the road again going W.T.F? The Wizzard
aren't screw in studs all about retention---taxi cabs and fleet vehicles never had screw in studs--- so if we don't believe the studs are pulling why screw ins if it has stock valve springs...
"it does not get driven much really".....do you have a problem with a valve or two sticking shut during longer term storage ?? If the valve is stuck shut, the weak link in the valvetrain can very well be the rocker stud. Normally they just pull out of the head, but breakage could also occur.
A strait edge across the top of the studs will tell you if you have more than 1 pulling up. Yes a stuck valve can also cause this. He says he was driving along pretty good at the time so I discounted that being the start point. The Wizzard
The valves can stick all of a sudden, but generally I see them stuck open. There's a ranger pickup here that was purring along just fine. It started with a "sputtering/shudder & 27 seconds later its trying to run on 5 cylinders, intake valve stuck open. Before that it was my buddies van. Ran fine the day before, ran fine in the AM till the stop sign about 1000 feet from the house. Left and Got about 5' from the stop sign and started missing- intake valve stuck open. So if you have one stuck closed, you are going to break something trying to open it with the valve train parts. I have a hard time believing its just old age and fatigue for a reason on the breakage.
I measured the push rod of the broken stud and it was approx 2 1/8 inch from top of head, the one next to it was only 1 7/8 inches from top of head. (both a TDC). I am thinking the short one is a collapsed lifter. I cannot imagine a came wearing a quarter of an inch. Hopefully it is not a combination of lifter and cam. Gonna extract the stud, put it back together and see what it does for a short period. if that one valve is not opening enough, I will put a new lifter in and then see what it does.
A stud on my small block broke also. I drilled it out and installed a screw in stud myself but that one broke as well. Turns out the pushrod hole had elongated a little. Machine shop machined the heads down for guide plates and all has been good 15 years later.
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