Rocker arm play - what is acceptable?
Hey all,
I'm doing the top end of my 4.6 and looking at the lifters, push rods and rocker shafts.
Lifters look great, pushrods look like pushrods, but when I took apart the rocker shafts I noticed the rockers themselves (in their regular position) had some noticeable lateral play, but when shifted to the section of the shaft where the spring resides, there was much less lateral movement.
The rocker shaft posts have very little tolerance due to the fact that they do not require movement or oiling.
That said, I have the following questions for those experienced valvetrain aficionados:
1- How much lateral play is too much?
B- Is the wear shared between the rocker and rocker arm requiring both to be replaced at the same time ie: cam and lifters?
and
3- how are the aftermarket shafts and rocker arms out there at the rover parts houses?
Cheers,
Paul.
I'm doing the top end of my 4.6 and looking at the lifters, push rods and rocker shafts.
Lifters look great, pushrods look like pushrods, but when I took apart the rocker shafts I noticed the rockers themselves (in their regular position) had some noticeable lateral play, but when shifted to the section of the shaft where the spring resides, there was much less lateral movement.
The rocker shaft posts have very little tolerance due to the fact that they do not require movement or oiling.
That said, I have the following questions for those experienced valvetrain aficionados:
1- How much lateral play is too much?
B- Is the wear shared between the rocker and rocker arm requiring both to be replaced at the same time ie: cam and lifters?
and
3- how are the aftermarket shafts and rocker arms out there at the rover parts houses?
Cheers,
Paul.
When I had to do my head gaskets, I tore the rocker assemblies apart to clean them. I inspected the "cup" which holds the push rod, push rods and lifters. The only thing I replaced were the lifters. I did notice some play in the rockers themselves but I did not replace any. I worked on "Winston" with a buddy who has way more experience than I do and he did not see the need to replace. I think if the rocker cup is really beat up you should replace.
RPI Engineering published a paragraph that says replace shafts and rocker arms as assemblies. Reasoning was the aluminum bearings get metal bits embedded, so don't just replace the shafts. It's an easy bit of work while you are in there. Costs not bad compared to a couple tanks full.
John-
I just went thru the RAVE manual to confirm what I thought. There are no bearings anywhere in the rocker shaft assemblies. If there are and you can tell me what I missed, I always enjoy increasing my knowledge base.
I just went thru the RAVE manual to confirm what I thought. There are no bearings anywhere in the rocker shaft assemblies. If there are and you can tell me what I missed, I always enjoy increasing my knowledge base.
the shaft wears at the arm, you will see it when you take them apart. If re-using old arms, Be sure to clean out all the arm oiling tunnels...they always fill with crud. DO NOT buy the cheap alum replacement rocker arms..POS's...you can still get OEM from UK....
Sorry for the confusion. The rocker arms bear on the shaft. Like XRAD said.
Last edited by JohnZo; Nov 3, 2022 at 07:15 PM. Reason: XRAD extra
I had a few of the 'steel' arms too for testing. the machining for the cups was horrible....waste of money unless they have fixed this issue
the cups were seated at significantly different depths with POOR retaining crimps on the cheapy aluminum version.
I ended up using a mix of the best new aluminum arms and the best old OEM aluminum arms......
I do have a set of 'Buick" specialty arms /shafts/ 'big' block end retainers saved for a rebuild someday....
the cups were seated at significantly different depths with POOR retaining crimps on the cheapy aluminum version.
I ended up using a mix of the best new aluminum arms and the best old OEM aluminum arms......
I do have a set of 'Buick" specialty arms /shafts/ 'big' block end retainers saved for a rebuild someday....
Thanks all for the positive responses and input.
I did notice the wear directly under each rocker, not nearly as bad as some worst case scenario images on line.
That said, the wear is noticeable and my main curiosity was is there supposed to be any lateral play whilst on the shaft?
There is a space right beside each rocker placement (where the spring resides) that is not worn at all and the lateral movement is somewhat reduced.
Is there much opportunity for the inside of the rocker to also be worn down?
If so then replacing the entire thing may be in the best interest, there are a few NOS parts still around.
I did notice the wear directly under each rocker, not nearly as bad as some worst case scenario images on line.
That said, the wear is noticeable and my main curiosity was is there supposed to be any lateral play whilst on the shaft?
There is a space right beside each rocker placement (where the spring resides) that is not worn at all and the lateral movement is somewhat reduced.
Is there much opportunity for the inside of the rocker to also be worn down?
If so then replacing the entire thing may be in the best interest, there are a few NOS parts still around.


