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Rocker Arm failure

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aroostok

Jedi Hopeful
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Recently I developed both a problem that seemed fuel related in that the B would run very rough from a stop. Worked fine in higher rpms. Started noticing, however, a loud rapping noise developing that became really noticeable the last time I had the B out. Turns out that when I pulled the valve cover gasket off I have a rocker arm that is just hanging loose with a lot of what looks like powder around where the bishing would be contacting the rocker arm shaft.
I know I will have to replace the rocker arm which will require pulling the head off, which in and of itself isn't that big a deal. This head was redone less than 5000 miles ago and all new valves and seals put in. Should I be looking for anything else when I take this head off? Is it a good idea to maybe replace the rocker shaft as well? Is this all that common a problem?

PS - on the random gallery posts kidus to the owner of the Boston Terrier driving his B. I've had Boston's since I was 12 years old (48 years now). Best dogs in the world. Wish the B was the same.
 
You don't need to pull the head to do that job, but it sounds like you've an oiling problem. The rocker bushes and the shaft will likely need replacing from the description. Pedestals and the way they line up to oil galley differ from 18GB to 18GH heads... is there a possibility you have a later set on an older head (or vice-versa)?
 
Just took the rocker assembly off and I definitely have to replace the shaft. I do believe it was an oil problem. This is an 18V engine. The rocker bushing was literally gone and the shaft worn. I am going to replace rockers and shaft. Since I haven't actually lifted the head off the block, can I assume I haven't upset anything with the head gasket and can just bolt back up after replacing the rockers?

Thanks much.
 
I had to rebuild the rockers on my 73 and used this guy to do the work. https://www.rockerarms.com/MG.htm He rebushed the rockers, resurfaced the tip of the rocker where it meets the valve and supplied a hardend rocker shaft and the whole thing came back looking and working better than new and should last a very very long time. It was not much more than 100 bucks and his turn around was very very fast.
 
I've got lots of good, used assemblies
 
My bad... meant 18-V-! Sorry.

Yup, just retorque to spec. Is there evidence of oil up there on the rest of the shaft? Just wondering what caused the deficiency. A localised (one hole in the shaft blocked) starvation or some blockage at the head/block interface... a shot of compressed air down the little supply hole couldn't hurt.
 
At the risk of being repetive, I have 2 18V heads, one a 1974, the other is a 1979. The 1979 has an offset oil feed to the rockers (rear most rocker pedistal); the 1974 has a straight oil feed. I had the same thing happen when I put the 1974 rocker on the 1979 head - oil starvation to the rockers, with subsiquent rocker arm failure by slipping off the valve. So, you might want to check that out.

Colin
 
"Pound that rock" Colin. The differences are obvious once you know what you're looking at... but it could be a trick to the 'uninitiated'.
 
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