VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1912-1928 rocker arms 1928 engine

Good Evening everyone, I've got a 28 engine in my 21 speedster and it's breaking rocker arms left and right. I have 5 broken ones in the garage right now. I rebuilt the engine but am using the same valve springs, and it did run for quite a while before this started happening. They are breaking between the rocker arm shaft and the adjuster. Has anyone else had a problem like this? It runs really good when they don't break. Any help at all on this would be greatly appreciated, I don't want to start it up again. And the person who had it before me didn't have this problem, is it just old age? What should I be looking for?

Remove the head, remove the valves. Use a reamer to relieve the valve guides. (Actually, it did not come with guides, and this was not a problem with the 4-cylinder engines.) However, a 6-cylinder has this problem regularly when left to sit for a long time. Must be the corn fuel?

You can buy nice new rocker arms for the 28. They would be perfect of the speedster but if you have a cover over them no one will see anyway.
http://www.billypossum.com/c&p_catalog/c&p_catalog_rev_031225.htm

Hi Mark,
What page are the new rocker arms on? I don't see them.

Regards
Al

Hi,

I believe C&P only sell the rocker bushings and shaft, not the rocker arms.

Dean

I did some checking, it was Neal Jern of Jern Thunderbolt that we got the set from. Neal passed away a while back and while someone was going to step in a continue production of the parts, I guess it never happened. You might do some checking and see if you can find a phone number, the email address was not working last time someone tried. You could try it anyway.
http://jernthunderbolt.com/Model%20T%20Parts%20.html
http://jernthunderbolt.com/index.html

I had exactly the same problem on another head that I reconditioned. Every time a rocker broke,I took the head off and reamed the valve guides a little more. I then realised that the valve guides were sticking out too far and the valve spring retainer was just catching them at the valve fully open position. I ended up with a set of oversized valve guides. I had no choice but to replace all the guides for a second time.

I have not attempted to start the engine after my first post. When I assembled the head, I used plenty of assembly lube on the valve guides and all the moving parts. On first start up and several after that, everything was fine. After several runs was when the rockers started breaking. Should the trough in the head where the valves are be filled with oil? Also should I be oiling the guides thru the springs before every run? It's starting to sound to me like a lubrication problem. Let me know your thoughts on this and thanks in advance for your help.

Lack of lubrication could be the problem.

In my '28 engines (I have two), I keep the troughs around the valve guides about 1/2 filled with oil. There should also be a felt pad laying over the rockers that you keep oily. And, some felt rings that sit around the ball end of the rock adjustment screws.

Since the oil pump does not deliver oil to the rocker assembly, the Chevy lubrication chart (in the owner's manual and shop manual) says to squirt oil up there every 50 miles. I generally squirt some oil around the rockers every time I take my truck out for a drive, just to be safe.

Hope this helps, Dean

Thanks for the input, Dean, I am really leaning toward lack of lubrication. I'm new to this and have to adjust my thinking so that I lube the top side more often. I'll let you know how it works out.

Just a thought, with a lack of valve stem lubrication or clearance problem, the valves usually tend to stick open (down) before sticking closed (up).

This is because the valve springs will exert less force than the rocker.

Have you checked the springs aren't coil bound at full rocker travel?

Well I found out what's breaking my rocker arms, the valve spring is all bound up, coil bind, no place to go. I have pulled the head off, took the springs off a couple of valves. For one, I think the springs are way over kill, they are very heavy and difficult to compress even with a valve spring compressor. I have new valves and the slot for the keeper is closer to the valve head than the stock Chevy ones, maybe that's part of the problem also. The guides look ok; I just need to find out what stock Chevy valve springs look like. I think Egge carries 28 Chevy valve springs so I may pay them a visit next week. Anything else I should look for while I have the head off? Thanks to all you guys for your help, it is appreciated.