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Last Sunday my 71 started running terrible and suddenly stalled out. It restarted but had a dead miss. I made it back to the garage and put it away. I checked it out today and found a broken rocker arm on #4. I was able to get some of the metal out. I’m thinking of just putting on a new rocker arm and hoping for the best. Is there anything else I should check?
Check the rocker ball, rocker nut and rocker stud for anything unusual.
Pull the pushrod and roll it on a flat surface.
Something beat the hell out of that rocker. Now you must wonder about about the other 15.
Perhaps a sticky valve stem / valve guide. Broken valve spring. IDK
Some cylinder heads were prone to having the rocker stud not pull out completely, but pull up enough to cause damage such as yours.
If this were mine, I would be deeply concerned where the shrapnel went. I think I would order an Intake manifold gasket and a oil pan gasket to be ready to go searching.
Last edited by HeadsU.P.; Sep 18, 2021 at 07:22 PM.
Check the rocker ball, rocker nut and rocker stud for anything unusual.
Pull the pushrod and roll it on a flat surface.
Something beat the hell out of that rocker. Now you must wonder about about the other 15.
Perhaps a sticky valve stem / valve guide. Broken valve spring. IDK
Some cylinder heads were prone to having the rocker stud not pull out completely, but pull up enough to cause damage such as yours.
If this were mine, I would be deeply concerned where the shrapnel went. I think I would order an Intake manifold gasket and a oil pan gasket to be ready to go searching.
In addition to that I would invest in a set of roller rockers and posi locks.
Don't worry about 'metal' getting into the engine. It would have to get sucked up into the pump, first; and that's not likely to happen.
The more important question is, "How did this happen in the first place?" That rocker was either made poorly or over-stressed. If it was made poorly, and came from the same batch as the others, WHEN will they start failing? If it was over-stressed, where is the problem in the valve train design or geometry?
You MUST determine how this occurred, or you will be scratching your head again when others begin to fail.
If that happened to me, at the very least I would replace all the existing stamped steel rocker arms with new ones. I would also seriously consider blue427 suggestion of installing a set of roller rockers and posi locks.
.
Last edited by sunflower 1972; Sep 19, 2021 at 01:27 PM.
To do nothing and not worry about the fragments as someone suggested is another disaster in the making.
Look real close at that rocker. There is a lot of metal missing!
The pump screen maybe blocked off now, restricting oil flow. Finer material will plug several oil filters, several times.
And Lord knows how much shrapnel is sitting in the lifter valley.
After everything with the valvetrain is repaired, the pan should come off. You should worry.
Yep would agree gotta find a reason that it happened. If you can't maybe replace all the rockers.
Is it possible that the rocker nut backed off and that one was loose for a while causing it to slap around and finally fracture. Check the other rockers see if any are loose. Check them for impending failure as well.
Dollars to donuts:
as it failed it spalled and some flakes & small bits shed as well as larger bits.
some of the smaller bits have already gotten past the screen & through the pump; or will.
Replace all 16 with some Comp Magnum roller tip style and short Poly-locs.......
The roller tip pieces get no love here but I have used them in stock-ish applications for 20 years......they are at least twice as strong as any standard ball stud rocker.
When you have the rockers off.....tap the heads of each valve with a small end plastic dead blow hammer. Give each one a good thwack...and you should hear each valve smack shut with a "cluck" sound. No cluck means investigate for a sticky or bent valve......
It looks like two pieces broke off of the rocker arm. The pieces were large enough that I was able to get them out without any issues. I don’t think any fragments made it inside the motor. Checking the numbers on the block it looks like the engine came out of a 1973 Monte Carlo with a 145 HP. Looking at the history I received when I purchased the 71 there was a cam installed, not sure what the specs are but it's definitely mild. It also looks like some head work was done. I checked the casting numbers on the heads, 333882, and did a little research. From what I read; these heads are pretty much junk. I bought a set of roller tip rockers and I'm going to install them this weekend.
Glad you found the missing pieces. I doubt that any problem results from 'small particles'. I now wonder if the PO did due diligence on determining proper length of pushrods, given that the cam was changed. When you pull the other rockers, I'd expect to see significant wear from hard rubbing with the 'ball'.
Slight chance your old rocker ***** are not the better slotted units which lube the rocker-arm pocket much better.
The 882 heads are not junk according to marinas. They make wonderful boat anchors, says-they.
With those heads, the rocker studs are press-in and can bend or actually pull loose with higher lift cams.
Once in awhile you can find used Comp Cams Roller-tip rockers for a decent price on EBay. Usually the seller wants to go full roller and sell the old ones.
You can see mine on My Profile, photo album, my build. Perfect condition at a discount.
But I would insist on NEW slotted rocker ***** & rocker nuts.
Last edited by HeadsU.P.; Sep 23, 2021 at 01:05 PM.
It is Awesome that you were able to find the parts and that it only made two parts!
Magnets are a wonderful thing to have on your engine. I have one on the Oil filter and another on the Oil Pan to hold stuff versus letting it flow through the engine's lubrication system. Strong magnets are a must. I can barely remove the one from the oil filter with two hands and a vice. When I cut the filter open the crap is attached to the magnet.
In that era, rocker arms failed like that on a regular basis, mainly in the early '70s. Just saying, there may not be a specific cause, just poor quality rockers. Hi Per Chevy engines in that era had a "o" designation on the tip, never seen one of those fail. The rockers with a triangle mark failed often.
I installed a set of Comp Cams roller tip rockers. All is well again. Still not sure what caused the rocker to break. Hopefully it was just poor quality. Anyway, thanks for all the help and suggestions. Very much appreciated!
After a few spirited driving lessons, you could pull the valve covers, one at a time, if you didn't "glue" both sides of the gasket.
You can purchase rocker arm oiler clips that block oil spray, in packs of 8. With those in place you can monitor the valvetrain at idle. Place a strip of cardboard between valve springs and V.C ledge. Start it up. Watch for any loose rockers, listen for weird sounds.
Shut it off, pull the clips, install cover, check the other head.
Rocker Arm
Glad you found the missing pieces. I doubt that any problem results from 'small particles'. I now wonder if the PO did due diligence on determining proper length of pushrods, given that the cam was changed. When you pull the other rockers, I'd expect to see significant wear from hard rubbing with the 'ball'.
