The Stovebolt Site Forums The Shop Area Engine Shop 261 Rocker Shafts & Supports

Recently purchased a remanned 1962 261 truck engine. Before inital start and run in I did perform the start up checks, engine runs great with no issues except slight ticking
from rockers and I passed this off as being solids and not unusally noisy and shut down engine after breakin and went to readjust lash and discovered slight wear on rocker tips to valve stems. I going to replace all the rockers and shafts with new or quality rebuilds. I noticed that the rocker shaft supports are made of aluminum and when I disassembled the shaft and rocker assemblies I noticed some galling on the bores of the aluminum supports.
My question is can steel supports be used in place of the aluminum ones?

Thanks
Bud

Those parts should never move w/r/t to each other.

My bad, at least some of them are iron.

I don’t know about the 261 but I would think the aluminum ones are not stock .I thought they were all cast

That's what I thought Kevin. I have 3 older 216's 2 later 235's and 1 '54 261 and they all have the cast "steel" supports. About 6 months back there was a seller on Ebay with a complete OEM assembly of shafts, rockers, springs and aluminum supports for a 1963 year model, trouble was the price was close to $900.00. I'll keep researching and see what comes in.
Bud

If you have access to a valve grinder you can resurface the rocker tips to make them flat. Sure saves on feeler gauges. I have ground them flat again (actually radiused when viewed looking at the shaft hole) using a bench belt/disc sander with an adjustable rest for the work-peice. You can have the rockers re-bushed too. I don't know if that's cheaper than buying reconditioned rockers but I'll bet someone on the site will have bought some recently. But if you do all that work you still have to come up with shafts if yours are worn. You can buy lash caps for the valve stems. They come in different sizes and thicknesses. They can correct the valve train geometry when using high lift cams. I have used them on my Norton motorcycle to good effect. They are harder than the valve stems.

On the matter of aluminum rocker stands remember that aluminum expands faster than steel when heated. So, the valve lash will increase as the engine heats up. If you set the valve lash hot and running then as the lash decreases when the engine is cold they will be less noisy.

I have been looking for an actual dimension for the factory pallet radius for years, never found it. This has been reported as the lift (not), 50% of the rocker ratio in inches (not), etc. There is math for it in theory, but above my pay grade.
Despite many remarks, there is no fixture, mechanism, device, pantograph etc. (described as part of a Black & Decker, Kwik-Way, Rottler, Sioux, Snap-On valve refacing machine) that copies or applies the original pad radius to the rocker arm's valve-side lever pallet. They all rely on operator discretion in how fast the rocker is rotated by hand, past the grinding wheel or belt and will ruin the rocker if not done carefully.

In the real world of auto repair back when mechanics were skilled tradesmen and not simply parts-swappers, untold thousands of rocker arms got resurfaced with those fixtures on valve grinding machines, without getting ruined. Yes, it takes some skill, something that will probably will never be seen again in today's throwaway culture.
Jerry

There are many YouTube videos showing this in use, but it suggests that it's automatic and following some fixture. It's not, but you can do a pretty good job just by paying attention. I've done rockers by hand on a grinding wheel with good results (shows no new pattern on the tappet or valve stem 5,000 miles later). Easier to hold the rocker straight to the abrasive by putting the shaft through it. The intake and exhaust rockers are different shapes but the pallets are the same.
Stop and examine the pallet under a strong lamp, tilt it slightly and rotate, and watch how the light passes across the curvature; if you see a line or ripple remove it. IMHO as long as you get this:
1. no flat spots
2. no edges
3. left to right surfaces an exact match
4. shiny!
it's probably good enough.

I have done them by hand on a paper wheel knife sharpener on a bench grinder (Dunn System). One wheel has grit embedded on it, while the other wheel is loaded with jeweler's rouge.
Takes a bit of a steady hand and you need to look at what's going on on every pass or so.
My aim is to remove metal evenly along the curved surface until the mark caused by the valve stem end just disappears.
Doing it this way, you can watch the mark disappear evenly along its entire width and length as you go, resulting in maintaining the original shape of the part.

I slowly did them on a power belt-sander and/or grinding wheel.
Polished to a smooth finish.

That was over 10 years ago.

It made a difference in the engine noise and performance.

I want to thank you fellow bolters for sharing your tips and tricks, the little tick, tick is going to be a distant memory.

Bud

If you don't have the dedicated rocker arm resurfacing fixture that used to be optional equipment on most valve grinders, a narrow belt sander that places like Harbor Freight sells, with a very fine grit belt is a pretty good substitute. Use Dykem or Prussian Blue to monitor your progress while doing the resurfacing. Once the contact pad is smooth, use a crocus cloth belt to put a mirror polish on it.
Jerry

Thanks, Jerry

With regards to resurfacing the rocker arm at the valve interface, does anyone know how the rocker arm tips are heat treated?

Just wondering if they are heat treated through, or just surface hardened - in which case a concern would be breaking thru the hardened surface, exposing the softer interior.

The reason I am asking is that I have some GMC 270 rocker arms that show some pitting. I had thought about trying to resurface them, however the service information says to replace them if they are worn, which leads me to believe that they may be only surface heat treated.

These appear to be cast or possibly forged. It this the same type that you are talking about?

Just curious...

Best Regards....