Cast iron rockers discussion

[2INSANE]

So why did gm decide to not make them anymore?

What are the common failures?

How can they be improved or modified to work better?

Anyone have experience with them?

What years did gm have them in the 6.2?

Etc...

 

[Barrman]

When I rebuilt my GEP 6500 I looked into which style of rocker arm was best. Here is what I came up with:

Cast iron
expensive to manufacture
Audable noise
Bushing can wear
Shaft can wear
I could not find a single incident of failure with the engine running resulting in a broken engine.

Stamped steel
Easy and cheap to manufacture
Relatively noiseless with engine running
Plastic locator buttons can and do fail. Causing the rocker to walk down the shaft. Sometimes the pushrod doesn’t break off and jam the cam. Sometimes it does.

I cleaned up a few sets of cast iron rockers and picked my best available used shafts and rockers to make a set. Yes, my engine idles loud. But in over 3 years of running since I built it. I haven’t given them a single thought until I read this thread. I can’t say it would be the same if I had spent the $50 for new buttons and gone stamped steel.

 

[cucvrus]

I have used both and never noticed the difference. If the engine is maintained they are both equal. I would agree with the cost cutting and lightning of weight. I don't think one is better than the other. Those old engines are crude by modern standards. But very reliable when kept stock and properly maintained. Good Luck. I have parts if you need some.

 

[2INSANE]

My first 6.2 was a 1983 civ GMC that had the cast iron rockers. After the lifters failed and starter bolt broke the block beyond repair at about 289k miles and 13 years of driving it everywhere, I took out the cast iron rockers and installed them in a surplus J-Code 6.2 that I refurbished.

2 years later and 20k miles...They are still doing well.

I read somewhere that some failures could be the pushrod wearing down the metal on the rockers and the push rods getting stuck in the rockers resulting in lifters/valves not properly working.

I also read that a failure could be that the arms could break as they are cast iron.

And they don’t lubricate the top end as good as pressed rockers.

Personally I love them! I think they are quieter and fit more firm on the pushrods with less movement.

It makes me wonder why GM only had them for a few years.

Anyone else have experience with them?