Rocker Arm Stud needs repacing ?
 

Took the truck out at the weekend and it started knocking, Found the problem when I got home. When I took the rocker cover off one in the rockers was sitting at an angle, Pulled it apart and found this :(

The rocker stud has a deep grove worn into it and the top of the valve stem is pitted.


I plan to replace the push rod, rocker stud and fit a new rocker kit.


Questions 1, What's the easiest way to replace the rocker stud ?

I've seen some videos with screw in studs but can that be done safely with the head still in the truck (I really don't want to have to take the head off if I don't have to)

Question 2, Will the valve stem top be ok as is or should I try to smooth and polish it ?

Re: Rocker Arm Stud needs repacing ?
 

The stud still has a lot of strength left. I would put on a new rocker and send it. The other option is to remove the head and fix everything properly. That will snowball into all new valves and all new rockers and a valve job.

Re: Rocker Arm Stud needs repacing ?
 

Choices!
Be cheap and tap the stud back in and pin it, clean the valve stem head, new rocker, set it up, run it.
And then wait for the wrong time for it all to come apart again. And maybe not that one either. If one pulled out, others could. Could have a lot more damage.
Or pop off both heads and rebuild or replace them.
Considering where you live it might be better to replace them.

Re: Rocker Arm Stud needs repacing ?
 

Does it look like the stud has pulled out ?

Re: Rocker Arm Stud needs repacing ?
 

I had a stud pull up on a 307 in a boat years ago. Just put the new stud in the freezer overnight, heated the head with a propane torch and tapped the new one in. Ran the boat for a couple of years after with no issues at all. I would replace it with a new one.

Re: Rocker Arm Stud needs repacing ?
 

Yes.

Re: Rocker Arm Stud needs repacing ?
 

The valve tip is hardened so it can be resurfaced when a valve job is done. the valve tip is damaged beyond the hardened part and if you put a rocker on that valve you are asking for trouble and valve train failure.

Re: Rocker Arm Stud needs repacing ?
 

Classic textbook failure. The books show using a stack of washers and a nut to pull out the old one. Then tapping the hole for a new screw-in one. Just make sure you get the tap straight.
Disclaimer: I've never had one fail in that way myself (but have seen it many times in many books), and I currently have heads with screw-in studs. So take my comments with a grain of salt.

Re: Rocker Arm Stud needs repacing ?
 

Without replacing that valve, another rocker will not sit right and this will likely happen again.

Re: Rocker Arm Stud needs repacing ?
 

BEFORE you pull the stud, drain the cooling system a little. Hole goes through to the cooling system.

Re: Rocker Arm Stud needs repacing ?
 

At these point a proper repair would be to pull the head and replace the vavle and has all new screw in studs put in

Re: Rocker Arm Stud needs repacing ?
 

How do I work out which size screw in stud I need ?

Re: Rocker Arm Stud needs repacing ?
 

What are you planning to do?
Replace the bad one or all of them.
If it’s likely just that one then you don’t need a screw in stud. A new press in one that’s pinned will work.
Did you check to see if that one is pulled out?

Stud size depends on your spring pressure.
Higher pressure needs bigger studs.

Re: Rocker Arm Stud needs repacing ?
 

First thing is you need to decide how long you need the repair to last. Less than a month, pull that stud and drive one in the hole and throw a new rocker on it. More than a month pull the heads and have them done. That valve tip is beat to pieces and will eat a rocker in short order based on my past experiences. The valve tip is what keep the rocker sitting correctly in the stud. When it gets rounded off the rocker leans to one side and begins to eat the side of the stud giving you what you have now. In my 40 + years of working on motors I have had to patch a few to get work in the morning or carry me till payday. Always hoping to have it last till I could fix it correctly.
Jimmy

Re: Rocker Arm Stud needs repacing ?
 

So I need to take the head off, fit a new valve and fit a set of screw in studs not just the knackered one, if I want it done right.

Re: Rocker Arm Stud needs repacing ?
 

Yes, if you want it to last any length of time. With a stock engine, there is no need for screw in studs.

If you happen to be close to Stonnall, Staffordshire, there is someone there that I know that could help you.

Re: Rocker Arm Stud needs repacing ?
 

I had a set of heads that I put on my Jimmy that had one stud put in a little crooked and the rocker didn't sit square on the valve. I added a lash cap to that one valve stem and have been running it 30 years that way.

Google lash cap and see how they are used.

You can buy screw in studs that don't have the hex on them. So stack some rocker pivot balls up on the pressed in stud and tighten a rocker nut down to pull the stud. Tap the hole and screw the stud in. Add lash cap to valve stem after cleaning it up and run it for as long as it goes.