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Rocker Arm Problem

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Javelin360 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Javelin360 Quote  Post ReplyReply Direct Link To This Post Topic: Rocker Arm Problem
    Posted: Oct/01/2018 at 6:00pm
I'm having a bit of trouble with 3 sets of rocker arms I replaced. I had a collapsed lifer so I pulled the intake and replaced all of the lifter. I inspected the rocker arms and found three sets that had galling between the pivots and the rockers so I replaced them with Sealed Power units. The silver ones are the Sealed Power units and the move around A LOT when you wiggle them. The heat glazed units are what was in the motor when I got it and none of them have any movement. I measured the pivots between the old units and the SP units and they were within .002 of each other. I don't have a real way to compare SP rockers to the old rockers. The lifter rods do not appear to be bent or worn.

I have swapped the position of the rockers to see if it changed anything but the movement problem persists no matter where the rockers are. One set of rockers I could get a .012 feeler gauge between the pivot and the rocker pivot surface. I removed .012 from the base of the pivots with my surface grinder and installed them back into the head. They still had movement. 

Any suggestions and can anyone identify the brand of the old rocker arms?








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motorhead_1 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote motorhead_1 Quote  Post ReplyReply Direct Link To This Post Posted: Oct/02/2018 at 4:07am
are the lifters pumped up?
checking on the correct stroke?
flat cam lobe?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 304-dude Quote  Post ReplyReply Direct Link To This Post Posted: Oct/02/2018 at 7:53am
Let's try something different... use a good used bridge with the new SP rocker set, and a SP bridge on a good used rocker set, and compare again.

I have a feeling the SP rockers are not within OEM standards. This could be one of those instances.

You may need to order a custom size push rod, or a set of adjustable push rods. Though, it can be expensive just for something so simple.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Trader Quote  Post ReplyReply Direct Link To This Post Posted: Oct/02/2018 at 9:31am
I have used the SP rocker but you will notice that they are stamped V, VI, VII or none.
I found slight differences between the V and VII and usually buy more then one set to get all with the same stamp. The VII had a larger diameter push rod recess and was overall longer then the V.  Currently all VI on my 401.
Have not seen the "none" but there are differences, and if the stamping is the indication, then I would tend to try and find a set and go from there.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote SC397 Quote  Post ReplyReply Direct Link To This Post Posted: Oct/02/2018 at 10:01am
If you have replaced 3 sets of rocker arms and you are still having a problem then, the rocker arms are not the problem.

Has the cam been replaced from the stock one?
Has a valve job been done before you started having the problem?
Why did the first lifter collapse?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 401MATCOUPE Quote  Post ReplyReply Direct Link To This Post Posted: Oct/02/2018 at 2:18pm
The factory V-8 units had both T and V stamped in them over the years, what you do have to becareful of the 6 cylinder rocker looks the same but the oil hole is at different angle and other small differences.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote SC397 Quote  Post ReplyReply Direct Link To This Post Posted: Oct/02/2018 at 2:43pm
Yea, I was thinking about the 6cyl rockers too.  The 6cyl ones (top) are actually longer.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Javelin360 Quote  Post ReplyReply Direct Link To This Post Posted: Oct/02/2018 at 9:02pm
Originally posted by motorhead_1 motorhead_1 wrote:

are the lifters pumped up?
checking on the correct stroke?
flat cam lobe?

Yes the lifters are pumped up. I pre lubed the oiling system before I ever started the engine also.
It's only the three new pairs of rocker arms that I am having trouble with. All the rockers that were not replaced have no slop.
The cam appears to be fine.
 
Originally posted by 304-dude 304-dude wrote:

Let's try something different... use a good used bridge with the new SP rocker set, and a SP bridge on a good used rocker set, and compare again.

I have a feeling the SP rockers are not within OEM standards. This could be one of those instances.

You may need to order a custom size push rod, or a set of adjustable push rods. Though, it can be expensive just for something so simple.

I did try swapping the old pivots into the new rockers and the new pivots into the old rocker. It did not seem to make a difference. I have also moved the new pairs of rockers to several different locations and they are still sloppy and the original sets have no slop.

I'm begining to think the SP pairs are out of spec as all three pairs have varied amounts of slop.

Originally posted by Trader Trader wrote:

I have used the SP rocker but you will notice that they are stamped V, VI, VII or none.
I found slight differences between the V and VII and usually buy more then one set to get all with the same stamp. The VII had a larger diameter push rod recess and was overall longer then the V.  Currently all VI on my 401.
Have not seen the "none" but there are differences, and if the stamping is the indication, then I would tend to try and find a set and go from there.

The three pairs all have the same stamping/slash marks. I spoke with a tech guy from SP and he said that the marks are put there by the manufacture. This implies to me that SP has someone else stamp these out.

Originally posted by SC397 SC397 wrote:

If you have replaced 3 sets of rocker arms and you are still having a problem then, the rocker arms are not the problem. 

Has the cam been replaced from the stock one?
Has a valve job been done before you started having the problem?
Why did the first lifter collapse?

I may have been unclear. I replaced three pairs of rocker arms not three entire sets. So the engine has 6 new rocker arms and 10 older rocker arms.

I purchased the engine from another party. It had been rebuilt with a stock cam, bored .030. I assume it had a valve job done but can't be sure. The motor ran fine until the lifter collapsed. I don't know why it collapsed.
The base of all the lifters had a very nice wear pattern and the cam looked good. I had a buddy that builds race engines inspect the surfaces for impropper wear. He said all the wear surfaces looked good.

The only rocker arms that have slop are the 6 that I replaced. All the others have no slop.

Originally posted by 401MATCOUPE 401MATCOUPE wrote:

The factory V-8 units had both T and V stamped in them over the years, what you do have to becareful of the 6 cylinder rocker looks the same but the oil hole is at different angle and other small differences.

Originally posted by SC397 SC397 wrote:

Yea, I was thinking about the 6cyl rockers too.  The 6cyl ones (top) are actually longer.
IMG_0806 by Rick Jones, on Flickr
IMG_0807 by Rick Jones, on Flickr
IMG_0805 by Rick Jones, on Flickr

As I mentioned earlier I spoke to a tech guy about the SP rockers. The part # R875 I have is supposed to be for an AMC 401 with bridged rockers. He is also leaning to the rockers not being made correctly. I purchased these things back in Jan of 2012 so I doubt that Summit or SP are going to replace them. 

 I supose that 6cyl units could have been errantly placed in an 8cyl box but how would I tell?

I was considering buying a set of Melling rocker arms but the pics on the Quadratec web site have the same stamping marks as the SP rockers that are giving me a problem. This leads me to believe that the Melling and SP brands are made by the same manufacture. 

Are there any other brands worth trying?




Edited by Javelin360 - Oct/02/2018 at 9:05pm
69 AMX     401/727
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09 Mustang Supercharged 4.6
14 Wrangler Sport 4X4
18 GMC Sierra
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SC397 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote SC397 Quote  Post ReplyReply Direct Link To This Post Posted: Oct/03/2018 at 8:12am
I still don't think that the rocker arms are the issue.
I have seen some not-so-great valve jobs where they ended up with different valve heights on the same head.  It makes a mess to deal with if you don't have adjustable rocker arms. You could lay a straight edge across the tops of the valves to see if they are the same height.
Check all of your push rod lengths and let us know what they are and of coarse if they are all the same or not.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Boris Badanov Quote  Post ReplyReply Direct Link To This Post Posted: Oct/03/2018 at 12:52pm
How is the oil pressure?


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