Well I'm in the process of removing my 3.1 classic stroker engine for sale, and decided to do a bit of measuring and testing before it leaves so the new owner has an idea of what to expect and what service it might need. It has been in service for quite sometime.

I wanted to do a leak down test, and the best way to do that is to remove the rocker arms and keep all the valves shut. That way as you apply compressed air to each cylinder, if and when the piston gets pushed to the bottom, it doesn't move the cam and open any valves. This way you don't have to get and maintain perfect TDC while you do each test.

So I merrily proceed to remove my rockers. As I begin removing them and wiping the oil off I am flabbergasted to see rather nasty pitting wear and un-even wipe patterns on each and every rocker. See pictures below. The cam has surprising little troublesome wear. Some of the rub patterns aren't exactly centered, and have variable widths, but there is no gouges or scratches or anything nasty. It is a regrind on a Nissan stock cam.

Let's keep in mind this motor has been running quite happily for an estimated 50-60,000 km over the past 10 years or more, and the prior owner put some miles on too, so its not this is new after a fresh cam. I've been keeping the lash set about once a year and never noticed the rocker damage. You can't see it without removing the rockers.

The rockers are NOT Nissan rockers. So I'm assuming the issue is mis-matched harndess. What is not clear to me is that the pitting is on the "Fore" part of the pad, before the actual contact patch. How does that happen without the forces of contact? The actual contact areas are more or less smooth, with varying amounts of wear from rocker to rocker, generally the contact patch is placed far too far forward (toward the valve), so the lash pads are wrong as well. 

Correct course of action is to get a new cam and some Nissan rockers (new or Delta regrinds) I suppose and start fresh. I should gather up my used rocker collection and send them off to Delta. Used to be $3 each to do, Likely more now...

So what's the current wisdom about sourcing rockers? ITM ones are available from Rock Auto, but after seeing this, I'm pretty sure I'm sticking with Nissan. 

 

 

Hi Jim.....I’m no engineer, but have never had any problems with Nissan reused without a regrind or Delta Cam regrind rockers. Folklore is that Nissan had it right with the two metals (cam and rockers) as far as compatibility. Delta does a beautiful job, cheap and quick to return. I always use Nissan Isky regrind Cams ( Stage III) and Delta regrind rockers and have never had a single problem in probably 20 builds if you count 510’s. 

Good Luck

Guy

Edited September 23, 20186 yr by Diseazd

If there are no grooves or low points on the "good" metal then the pits are really just a cosmetic issue.  Function versus appearance.  You might create a bunch of extra work and future problems by "fixing" the pits.  Did you measure lash before removal?  It would have increased if you had wear problems.

An alternative view.

This is very interesting! Mismatched hardness seems the culprit or possibly a poor break in period? Bad oil in the beginning?

Lash has been stable for a number of years. 

I'd never attempt to fix the pits, just get fresh surfaced rockers from Delta. I have a 'few' extra's laying around. I wonder if I get a discount if I send them a couple hundred.....  

Courtesy and couple of other Nissan parts supplies show ~$37 USD per rocker for new ones. 

Maybe the most surprising thing I see about this is how little damage has happened to the cam given the mileage and rocker condition. 

10 minutes ago, zKars said:

Lash has been stable for a number of years. 

I'd never attempt to fix the pits, just get fresh surfaced rockers from Delta.

Maybe the most surprising thing I see about this is how little damage has happened to the cam given the mileage and rocker condition. 

No offense, but this is a classic case of cognitive bias.  You're planning to "fix" what looks bad, but isn't measurably bad.  The pits might actually hold oil for better lubrication.

Anybody ever seen cracked big ends on connecting rods?  They look broken.

https://www.eeuroparts.com/blog/1939/engine-might-cracked-connecting-rods/

Why would you ever reuse those rockers when for under $50.00 you could have beautiful Nissan Delta regrinds? I can see reusing the cam if it shows no damage, but never those rockers. Everywhere there is a pit, there is a little nasty piece of metal hopefully in your oil filter. Go with the regrinds IMHO

2 minutes ago, Diseazd said:

 beautiful 

I'm just posting for fun so don't get mad.  You're still talking about appearance, not function.

Big picture, when you do things that don't really need doing you often end up with a whole new set of problems.  So, estimate time needed to get the work done then double or triple it, and the cost.  You might flatten your cam lobes, for example.  Do you want to drive it or have a picture of nice looking parts that you almost never see?

I would never get mad at you Z Head even when you can sometimes be a D Head (LOL). I always appreciate your efforts.....even when I disagree with you. 

Guy

So I have a question about identifying Nissan rockers.

While I have a 'few' rockers and have handled many, I have not studied the markings in detail. My "assumption" and memory said there was a nissan symbol on them. Now looking at the ones on this head, and some of the others, I see really only two patterns.

One has a trapezoid symbol, then a 6 (most but not all) with a following dot pattern or number,  or a 3 or 4 digit alpha string starting with S and sometimes a dot pattern. It was the little trapeziod I always thought was the Nissan identifier, but admittedly that is a very very old memory

Since all but a couple of the 12 on mine where the S type, I assumed them to be ne non-Nissan, but I'm not sure. 

Anyone with experience in these markings? 

Cause if they ARE all Nissan, then the pitting and deterioration may be oil choice related or oil volume or something else. 

Edited September 23, 20186 yr by zKars

I started a thread on rocker arms a few years ago over on Hybridz.  Haven't clicked through the links again so don't know how many are good.

http://forums.hybridz.org/topic/119576-rocker-arms-state-of-the-situation/

Nothing that indicates Nissan......I sent off 72 rockers to Delta Cams about 5 years ago. I was afraid they may stop resurfacing the rockers. Here are numbers from one box.

Edited September 23, 20186 yr by Diseazd