Rocker arm valve surfaces

[300I6Ranger4x4]

Why are some rocker arm valve surfaces different shapes and recessed? They are either a full circular shape, or a circle with a flat side cut out..

 

[300I6Ranger4x4]

Pic #2

Another shot

 

[enjr44]

My guess is that they are cast and then machined to correct configuration/specifications.

Drill/machine the hole, and then machine the two ends for proper size.

 

[gw33gp]

Are you sure they have not worn that way? Looks to me that new rocker arms are in order for you.

 

[300I6Ranger4x4]

They should all be flush I assume though.... Very confused what to do now.. I was just gonna go to the jy and grab some rockers that are still good with flush valve surfaces..

Just doesn't make sense though. Very strange because they don't look like they've been worn down to that much...

 

[TxGasRacer]

It happens because of the fact that the rocker cups and rocker tips along with the push rods are NOT pressure oiled.Just the shaft assembly is pressure fed with oil,But the pushrods ends and rocker cups and rocker tips are Not pressure fed with oil.The rocker cups,rocker tips and push rods are splash oiled so the rocker cups,rocker tips that hit the valve stems and the push rod ends wear out prematurely because of Not being pressure fed with oil.

 

[300I6Ranger4x4]

The tips that are recessed look machined like that though. Not worn. The only ones recessed like that are the fully circular ones too...

 

[enjr44]

The tips that are recessed look machined like that though. Not worn. The only ones recessed like that are the fully circular ones too...

I still say they were made that way. I bet if you measure the diameter of the circle it is way bigger than the diameter of a valve stem. The end of a worn out rocker does not have a circle worn into it. It is more like a square with curved ends from rubbing back and forth.

The one in the picture with the square-ish end is a normal wear pattern (I don't mean wore out; just, shined up) for a rocker arm.

 

[300I6Ranger4x4]

So you think maybe they were cast then machined to proper spec.. Makes the most sense. The motor would have been tickin like a bastard if they where that worn. She barely ticked before. They must have to machine some of the castings a bit to achieve proper rocker ratio maybe? Idk. Lol

 

[alwaysFlOoReD]

My personal opinion is; it's wear. The circular depression being caused by too much lash, so instead of sliding along the top of the valve stem it hammers down on it. Perhaps caused by a sticking or collapsed lifter or if adjustable, improper valve lash. The pic of the squared one is normal in my eyes.

 

[2trux]

I'm going with worn out. I think if they needed to reduce the amount of metal on the tip of the rocker arm they would cut down the whole surface and not just a small circle. To machine small circles of differing depths would be way too custom for a mass produced engine. I would replace those arms that have the divots worn in them.

 

[enjr44]

I'm going with worn out. I think if they needed to reduce the amount of metal on the tip of the rocker arm they would cut down the whole surface and not just a small circle. To machine small circles of differing depths would be way too custom for a mass produced engine. I would replace those arms that have the divots worn in them.

I have been persuaded. Replace them!!!